MAX5926EEE+T - Maxim Integrated

General Description

The MAX5924/MAX5925/MAX5926 1V to 13.2V hot-swap

controllers allow the safe insertion and removal of circuit

cards into live backplanes. These devices hot swap supplies

ranging from 1V to 13.2V provided that the device supply

voltage, VCC, is at or above 2.25V and the hot-swapped

supply, VS, does not exceed VCC.

The MAX5924/MAX5925/MAX5926 hot-swap controllers

limit the inrush current to the load and provide a circuit-

breaker function for overcurrent protection. The devices

operate with or without a sense resistor. When operating

without a sense resistor, load-probing circuitry ensures a

short circuit is not present during startup, then gradually

turns on the external MOSFET. After the load probing

is complete, on-chip comparators provide overcurrent

protection by monitoring the voltage drop across the

external MOSFET on-resistance. In the event of a fault

condition, the load is disconnected.

The devices include many integrated features that reduce

component count and design time, including configurable

turn-on voltage, slew rate, and circuit-breaker threshold. An

on-board charge pump provides the gate drive for a low-

cost, external nMOSFET.

The MAX5924/MAX5925/MAX5926 are available with

open-drain PGOOD and/or PGOOD outputs. The

MAX5925/MAX5926 also feature a circuit breaker

with temperature-compensated RDS(ON) sensing. The

MAX5926 features a selectable 0ppm/°C or 3300ppm/°C

temperature coefficient. The MAX5924 temperature

coefficient is 0ppm/°C and the MAX5925 temperature

coefficient is 3300ppm/°C. Autoretry and latched fault-

management configurations are available (see the

Selector Guide).

Applications

●Base Stations

●RAID

●Remote-Access Servers

●Network Routers and Switches

●Servers

●Portable Device Bays

Benets and Features

●Hot Swap 1V to 13.2V with VCC ≥ 2.25V

●Drive High-Side nMOSFET

●Operation With or Without RSENSE

●Temperature-Compensated RDS(ON) Sensing

●Protected During Turn-On into Shorted Load

●Adjustable Circuit-Breaker Threshold

●Programmable Slew-Rate Control

●Programmable Turn-On Voltage

●Autoretry or Latched Fault Management

● 10-Pin μMAX® or 16-Pin QSOP Packages

19-3443; Rev 4; 1/16

μMAX is a registered trademark of Maxim Integrated Products, Inc.

Selector Guide and Ordering Information appears at end of

data sheet.

MAX5925

MAX5926

SC_DET

GND

VCC

REMOVABLE CARD

2.25V TO 13.2V

BACKPLANE

CB SENSEGATE

GND

1V TO VCC

VCC

OUT

RSC

RCB

VOUT

SEE FIGURE 1 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITHOUT RSENSE.

TYPICAL OPERATION WITHOUT RSENSE

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

Typical Operating Circuits

MAX5924

MAX5926

GND

VCC

REMOVABLE CARD

2.25V TO 13.2V

BACKPLANE

CB SENSE GATE

GND

1V TO VCC

VCC

OUT

RCB

RSENSE VOUT

SEE FIGURE 2 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITH RSENSE.

TYPICAL OPERATION WITH RSENSE

EVALUATION KIT AVAILABLE

*GATE is internally driven and clamped. Do not drive GATE with external source.

(All voltages referenced to GND, unless otherwise noted.)

VCC ........................................................................-0.3V to +14V

GATE* ....................................................................-0.3V to +20V

All Other Pins ......... -0.3V to the lower of (VCC + 0.3V) or +14V

SC_DET Current (200ms pulse width, 15% duty cycle) ..140mA

Continuous Current (all other pins) ....................................20mA

Continuous Power Dissipation (TA = +70°C)

10-Pin μMAX (derate 6.9mW/°C above +70°C) ..........556mW

16-Pin QSOP (derate 18.9mW/°C above +70°C) .....1509mW

Operating Temperature Range ......................... -40°C to +105°C

Junction Temperature ...................................................... +150°C

Storage Temperature Range ............................ -65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Soldering Temperature (reflow) .......................................+260°C

(VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC;

TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1μF, SLEW = open,

TA = +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLIES

VCC Operating Range VCC 2.7 13.2 V

VS Operating Range VSVS as dened in Figure 1 1.0 VCC V

Supply Current ICC FET is fully enhanced, SC_DET = VCC 1.5 2.5 mA

UNDERVOLTAGE LOCKOUT (UVLO)

UVLO Threshold VUVLO Default value, VS and VCC increasing, Figure 1 1.73 2.06 2.47 V

VCC UVLO Deglitch Time tDG (Note 2) 900 µs

VCC UVLO Startup Delay tD,UVLO 123 200 350 ms

LOAD-PROBE

Load-Probe Resistance (Note 3) RLP

2.7V < VCC < 5V 4 30 65 Ω

5V < VCC < 13.2V 3 10 20

Load-Probe Timeout tLP 43 102 205 ms

Load-Probe Threshold Voltage VLP,TH (Note 4) 172 200 235 mV

CIRCUIT BREAKER

Circuit-Breaker Programming

Current

ICB

TC = high (MAX5926),

MAX5924

VCC = 2.7V and VCB = 1V 37

µA

2.7V ≤ VCC ≤ 13.2V 34 37 42

ICB25

TC = low

(MAX5926),

MAX5925 (Note 5)

VCC = 2.7V, VCB = 1V,

TA = +25°C 30 40 50

VCC = 2.7V, VCB

= 1V, TA = +105°C

(MAX5925D)

45 60 80

2.7V ≤ VCC ≤ 13.2V,

TA = +25°C 40 50 60

2.7V ≤ VCC ≤ 13.2V,

TA = +105°C (MAX5925D) 40 60 80

ICB85

TC = low

(MAX5926),

MAX5925 (Note 5)

VCC = 2.7V and

VCB = 1V, TA = +85°C 40 50 60

2.7V ≤ VCC ≤ 13.2V,

TA = +85°C 50 60 70

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Absolute Maximum Ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these

or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect

device reliability.

Electrical Characteristics

(VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC;

TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1μF, SLEW = open,

TA = +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Circuit-Breaker Programming

Current During Startup ICB,SU 2 x ICB µA

Circuit-Breaker Enable Threshold VCB,EN VGATE - VOUT, rising gate voltage (Note 6) 2.3 3.6 4.65 V

Circuit-Breaker Comparator Offset

Voltage VCB_OS 0.3 ±4.7 mV

Fast Circuit-Breaker Offset

Resistor RCBF Figure 3 1.2 1.9 2.7 kΩ

Slow Circuit-Breaker Delay tCBS VCB - VSENSE = 10mV 0.95 1.6 2.95 ms

Fast Circuit-Breaker Delay tCBF VCB - VSENSE = 500mV 280 ns

Circuit-Breaker Trip Gate Pulldown

Current IGATE,PD

VGATE = 2.5V, VCC = 13.2V, TA = -40°C to

+85°C 13.5 27 mA

VGATE = 2.5V, VCC = 13.2V, TA = -40°C to

+105°C (MAX5925D) 12 27 mA

Circuit-Breaker Temperature

Coefcient TCICB

MAX5924, TC = high (MAX5926) 0 ppm/°C

MAX5925, TC = low (MAX5926) 3300

OUT Current IOUT 120 µA

MOSFET DRIVER

External Gate Drive VGS VGATE - VOUT

2.7V ≤ VCC ≤ 13.2V, TA

= -40°C to +85°C 4.2 5.5 7.2

2.7V ≤ VCC ≤ 13.2V,

TA = -40°C to +105°C

(MAX5925D)

4.0 5.5 7.2

Load Voltage Slew Rate SR SLEW = open, CGATE = 10nF 2.19 9.5 V/ms

CSLEW = 300nF, CGATE = 10nF (Note 8) 0.84

Gate Pullup Current Capacity IGATE VGATE = 0V 239 µA

ENABLE COMPARATOR

EN, EN1 Reference Threshold VEN/UVLO

VEN (MAX5924/MAX5925) or

VEN1 (MAX5926) rising, TA = -40°C to +85°C 0.747 0.795 0.850

VEN (MAX5925D) rising,

TA = -40°C to +105°C 0.747 0.795 0.875

EN, EN1 Hysteresis VEN,HYS 30 mV

EN, EN1 Input Bias Current IEN

EN (MAX5924/MAX5925) = VCC,

EN1 (MAX5926) = VCC

±8 ±50 nA

DIGITAL OUTPUTS (PGOOD, PGOOD)

Power-Good Output Low Voltage VOL IOL = 1mA 0.3 0.4 V

Power-Good Output Open-Drain

Leakage Current IOH PGOOD/PGOOD = 13.2V 0.2 1 µA

Power-Good Trip Point VTHPGOOD VGATE - VOUT, rising gate voltage VCB_EN 3.6 4.7 V

Power-Good Hysteresis VPG,HYS 0.36 V

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Electrical Characteristics (continued)

(VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC;

TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1μF, SLEW = open,

TA = +25°C, unless otherwise noted.) (Note 1)

Note 1: All devices are 100% tested at TA = +25°C and +85°C. All temperature limits at -40°C are guaranteed by design.

Note 2: VCC drops 30% below the undervoltage lockout voltage during tDG are ignored.

Note 3: RLP is the resistance measured between VCC and SC_DET during the load-probing phase, tLP.

Note 4: Tested at +25°C and +85°C. Guaranteed by design at -40°C.

Note 5: The circuit-breaker programming current increases linearly from VCC = 2.25V to 5V. See the Circuit-Breaker Current vs.

Supply Voltage graph in the Typical Operating Characteristics.

Note 6: See the Startup Mode section for more information.

Note 7: VGATE is clamped to 17V (typ) above ground.

Note 8: dv/dt = 330 x 10-9/CSLEW (V/ms), nMOS device used for measurement was IRF9530N. Slew rate is measured at the load.

(VCC = 5V, CL = 1μF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LOGIC AND TIMING (TC, LATCH (MAX5926), EN2 (MAX5926)

Autoretry Delay tRETRY Autoretry mode 0.6 1.6 3.3 s

Input Voltage VIH 2.0 V

VIL 0.4

Input Bias Current IBIAS Logic high at 13.2V 3 µA

Time to Clear a Latched Fault TCLR

MAX5924A/MAX5924B

MAX5925A/MAX5925B

MAX5926 in latched mode

200 µS

MAX5926 SUPPLY CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

ICC (mA)

MAX5924 toc02

-40 -15 10 35 60 85

0.4

0.8

1.2

1.6

2.0

2.4

VCC = 13.2V

VCC = VS

VCC = 5.0V

VCC = 3.0V

VCC = 2.25V

GATE-DRIVE VOLTAGE

vs. SUPPLY VOLTAGE

MAX5924 toc03

(V)

VGATE - VS (V)

1210864

2 14

VS = 1V

VS = 3V

VS = 5V

VS = VCC

MAX5926 SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX5924 toc01

(V)

ICC (mA)

1210864

0.4

0.8

1.2

1.6

2.0

2 14

VCC = VSENABLED

DISABLED

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Electrical Characteristics (continued)

Typical Operating Characteristics

(VCC = 5V, CL = 1μF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.)

CIRCUIT-BREAKER CURRENT

vs. SUPPLY VOLTAGE (TC = 0ppm/°C)

MAX5924 toc07

VCC (V)

ICB (µA)

12108642 14

VCC = VS

38.4

38.6

38.8

39.0

39.2

39.4

38.2

CIRCUIT-BREAKER PROGRAMMING

CURRENT vs. TEMPERATURE

MAX5924 toc08

TEMPERATURE (°C)

ICB (µA)

603510-15

-40 85

VCC = VS = 5V

TC = 3300ppm/°C

TC = 0ppm/°C

SLEW RATE vs. CSLEW

MAX5924 toc09

CSLEW (nF)

SLEW RATE (V/ms)

1500

1000500

100

0.1

0 2000

GATE DRIVE VOLTAGE

vs. TEMPERATURE

TEMPERATURE (°C)

VGS (V)

MAX5924 toc04

-40 -15 10 35 60 85

3.0

3.5

4.0

4.5

5.0

5.5

6.0

VCC = 13.2V

VCC = 5.0V

VCC = 3.0V

VCC = VS

CIRCUIT-BREAKER CURRENT

vs. HOT-SWAP VOLTAGE

MAX5924 toc05

VS (V)

ICB (µA)

12108642

0 14

VCC = 13.2V

TC = 3300ppm/°C

TC = 0ppm/°C

CIRCUIT-BREAKER CURRENT

vs. SUPPLY VOLTAGE (TC = 3300ppm/°C)

MAX5924 toc06

VCC (V)

(µA)

1210864

2 14

VCC = VS

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

Maxim Integrated

│

www.maximintegrated.com

Typical Operating Characteristics (continued)

(VCC = 5V, CL = 1μF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.)

TURN-ON WAVEFORM

(CSLEW = OPEN)

MAX5924 toc10

PGOOD

OUT

GATE 5V/div

5V/div

200µs/div

TURN-ON WAVEFORM

(CSLEW = 330nF)

MAX5924 toc11

PGOOD

OUT

GATE 5V/div

5V/div

2ms/div

TURN-OFF WAVEFORM

MAX5924 toc12

PGOOD

GATE

EN1 5V/div

5V/div

2µs/div

OVERCURRENT CIRCUIT-BREAKER EVENT

MAX5924 toc13

OUT

GATE

IFET

10V/div

5V/div

10V/div

400µs/div

tCBS

1A/div

PGOOD

SHORT-CIRCUIT CIRCUIT-BREAKER EVENT

MAX5924 toc14

OUT

GATE

IFET

5V/div

2µs/div

1A/div

PGOOD

AUTORETRY DELAY

MAX5924 toc15

OUT

SC_DET

EN1 5V/div

100mV/div

5V/div

400ms/div

tRETRY

tD,UVLO

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

Maxim Integrated

│

www.maximintegrated.com

Typical Operating Characteristics (continued)

(VCC = 5V, CL = 1μF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.)

OVERCURRENT FAULT AND

AUTORETRY DELAY

MAX5924 toc16

OUT

SC_DET

EN1 5V/div

200mV/div

5V/div

400ms/div

GATE 5V/div

UVLO DELAY AND LOAD PROBING

MAX5924 toc17

OUT

SC_DET

EN1 5V/div

100mV/div

5V/div

40ms/div

tLP

tD,UVLO

UVLO RESPONSE

MAX5924 toc18

VCC

GATE 2V/div

1V/div

200µs/div

>tDG

UVLO DEGLITCH RESPONSE

MAX5924 toc19

VCC

GATE

2V/div

1V/div

200µs/div

<tDG

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

Maxim Integrated

│

www.maximintegrated.com

Typical Operating Characteristics (continued)

NAME FUNCTION

MAX5924A/

MAX5924C/

MAX5925A/

MAX5925C

MAX5924B/

MAX5924D/

MAX5925B/

MAX5925D

MAX5926

1 1 1 VCC

Power-Supply Input. Connect VCC to a voltage between 2.47V and 13.2V.

VCC must always be equal to or greater than VS (see Figure 1).

2 2 2 SC_DET

Short-Circuit Detection Output. Connect SC_DET to VOUT through a series

resistor, RSC, when not using RSENSE. SC_DET forces current (limited to

≈200mA) into the external load through RSC at startup to determine whether

there is a short circuit (load probing). Connect SC_DET directly to VCC when

using RSENSE, Do not connect SC_DET to VCC when not using RSENSE in an

attempt to disable load probing.

3 3 — EN

ON/OFF Control Input. Drive EN high to enable the device. Drive EN low to

disable the device. An optional external resistive-divider connected between

VCC, EN, and GND sets the programmable turn-on voltage.

4 — 4 PGOOD Open-Drain Active-Low Power-Good Output

— 4 7 PGOOD Open-Drain Active-High Power-Good Output

5 5 5 GND Ground

6 6 12 SLEW

Slew-Rate Adjustment Input. Connect an external capacitor between SLEW

and GND to adjust the gate slew rate. Leave SLEW unconnected for the default

slew rate.

7 7 13 GATE Gate-Drive Output. Connect GATE to the gate of the external n-channel

MOSFET.

8 8 14 OUT Output Voltage. Connect OUT to the source of the external MOSFET.

9 9 15 SENSE

Circuit-Breaker Sense Input. Connect SENSE to OUT when not using an

external RSENSE (Figure 1). Connect SENSE to the drain of the external

MOSFET when using an external RSENSE (Figure 2).

10 10 16 CB Circuit-Breaker Threshold Programming Input. Connect an external resistor,

RCB, from CB to VS to set the circuit-breaker threshold voltage.

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

SENSE

OUT

GATEPGOOD (PGOOD)

SC_DET

VCC

MAX5924

MAX5925

MAX

TOP VIEW

SLEW

( ) FOR THE MAX5924A, MAX5924C, MAX5925A, AND MAX5925C.

GND

VCC CB

SENSE

OUT

GATE

SLEW

N.C.

QSOP

SC_DET

EN1

EN2

PGOOD

GND

PGOOD

LATCH

MAX5926

Pin Congurations

Pin Description

NAME FUNCTION

MAX5924A/

MAX5924C/

MAX5925A/

MAX5925C

MAX5924B/

MAX5924D/

MAX5925B/

MAX5925D

MAX5926

— — 3 EN1

Active-High ON/OFF Control Input. Drive EN1 high to enable the device when

EN2 is low. Drive EN1 low to disable the device, regardless of the state of EN2.

An optional external resistive-divider between VCC, EN1, and GND sets the

programmable turn-on voltage while EN2 is low.

— — 6 EN2

Active-Low ON/OFF Control Input. Drive EN2 low to enable the device when

EN1 is high. Drive EN2 high to disable the device, regardless of the state of

EN1.

— — 8 LATCH Latch Mode Input. Drive LATCH low for autoretry mode. Drive LATCH high for

latched mode.

— — 9 TC

Circuit-Breaker Temperature Coefcient Selection Input. Drive TC low to select

a 3300ppm/°C temperature coefcient. Drive TC high to select a 0ppm/°C

temperature coefcient.

— — 10, 11 N.C. No Connection. Not internally connected.

— — EP EP Exposed Pad. Connect EP to GND.

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Pin Description (continued)

Figure 1. Typical Operating Circuit (Without RSENSE)

Figure 2. Typical Operating Circuit (With RSENSE)

MAX5925

MAX5926

SC_DET

PGOOD**

SLEW

PGOOD (PGOOD*)

VCC

REMOVABLE CARD

2.25V TO 13.2V

BACKPLANE

TC** LATCH**

SENSEGATE

EN (EN1**)

1V TO VCC

VCC

CSLEW

OUT

GND

RSC

RCB

*MAX5925A AND MAX5925C.

**MAX5926.

GND

V+

EN2 EN2**

ON (ON*)

DC-DC CONVERTER

20kΩ

10Ω

1µF

MAX5924

MAX5926

SC_DET

PGOOD**

SLEW

PGOOD (PGOOD*)

VCC

REMOVABLE CARD

2.25V TO 13.2V

BACKPLANE

LATCH**TC**

SENSE GATE

EN (EN1**)

1V TO VCC

VCC

CSLEW

OUT

GND

RCB

*MAX5924A AND MAX5924C.

**MAX5926.

GND

DC-DC CONVERTER

V+

EN2 EN2**

ON (ON*)

20kΩ

RSENSE

VCC

10Ω10Ω

1µF

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Figure 3. Functional Diagram

LOGIC

CONTROL

OSCILLATOR

TIMER

VZ = 9V

CHARGE PUMP

EN/(EN1***)

SLEW

VCC

GATE

VCC

PGOOD**

OUT

SC_DET

GND

0.8V

1.24V

EN2***

SENSE LATCH***

PGOOD*

0.2V

*MAX5924B, MAX5924D, MAX5925B, MAX5925D, MAX5926 ONLY.

**MAX5924A, MAX5924C, MAX5925A, MAX5925C, MAX5926 ONLY.

***MAX5926 ONLY.

TC***

SLOW

COMPARATOR

FAST

COMPARATOR

RLP

RCBF

VCB,TH

VCBF,TH

ICB

MAX5924

MAX5925

MAX5926

N2µA

75kΩ

50kΩ

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Detailed Description

The MAX5924/MAX5925/MAX5926 are hot-swap controller

ICs designed for applications where a line card is inserted

into a live backplane. Normally, when a line card is

plugged into a live backplane, the card’s discharged filter

capacitors provide a low impedance that can momentarily

cause the main power supply to collapse. The MAX5924/

MAX5925/MAX5926 are designed to reside either in the

backplane or in the removable card to provide inrush

current limiting and short-circuit protection. This is

achieved using an external nMOSFET and an optional

external current-sense resistor.

Several critical parameters can be configured:

●Slew rate (inrush current)

●Circuit-breaker threshold

●Turn-on voltage

●Fault-management mode (MAX5926)

●Circuit-breaker temperature coefficient (MAX5926)

See the Selector Guide for a device-specific list of factory-

preset features and parameters.

Startup Mode

It is important that both VCC and VS rise at a minimum

rate of 100mV/ms during the critical time when power

voltages are below those values required for proper logic

control of internal circuitry. This applies for 0.5V ≤ VCC ≤

2.5V and 0.5V ≤ VS ≤ 0.8V. This is particularly true when

LATCH is tied high.

The MAX5924/MAX5925/MAX5926 control an external

MOSFET placed in the positive power-supply pathway.

When power is first applied, the MAX5924/MAX5925/

MAX5926 hold the MOSFET off indefinitely if the supply

voltage is below the undervoltage lockout level or if the

device is disabled (see the EN (MAX5924/MAX5925),

EN1/EN2 (MAX5926) section). If neither of these conditions

exist, the device enters a UVLO startup delay period for

≈200ms. Next, the MAX5924/MAX5925/MAX5926 detect

whether an external sense resistor is present; and then

autoconfigure accordingly (see Figure 4).

● If no sense resistor is present, bilevel fault protection

is disabled and load-probing circuitry is enabled (see

the Load Probing section).

If load probing is not successful, the fault is managed

according to the selected fault management mode

(see the Latched and Autoretry Fault Management

section).

If load probing (see the Load Probing section) is successful,

slew-rate limiting is employed to gradually turn on the

MOSFET.

● If the device detects an external RSENSE, circuit-

breaker threshold is set at 2xICB, the slow comparator

is disabled, the startup phase begins without delay

for load probing, and slew-rate limiting is employed to

gradually turn on the MOSFET.

During the startup phase, the voltage at the load, VOUT,

rises at a rate determined by the selected slew rate (see

the Slew Rate section). The inrush current (IINRUSH)

to the load is limited to a level proportional to the load

capacitance (CL) and the slew rate:

INRUSH

C SR

1000

where SR is the slew rate in V/ms and CL is load capacitance

in μF.

For operation with and without RSENSE, once VGATE -

VOUT exceeds VCB,EN, PGOOD and/or PGOOD assert.

When VGATE - VOUT = VCB,EN, the devices enable

standard bilevel fault protection with normal ICB (see the

Bilevel Fault Protection section).

Figure 4. Startup Flow Chart

VCC RISES ABOVE VUVLO

ENABLE TRUE?

UVLO 200ms DELAY

VGS VTHPGOOD

FAULT MANAGEMENT

DISABLE FAULT PROTECTION,

ENABLE LOAD PROBE

SLEW-RATE-LIMITED

STARTUP

RSENSE

PRESENT?

VGS VCB,EN

PGOOD

YES

LOAD PROBE

SUCCESSFUL?

ENABLE STANDARD BILEVEL

FAULT PROTECTION

BEGIN NORMAL OPERATION

ICB,SU = 2 x ICB

DISABLE SLOW

COMPARATOR

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Load Probing

The devices’ load-probing circuitry detects short-circuit

conditions during startup. Load probing is active only

when no external RSENSE is detected. As the device

begins load probing, SC_DET is connected to VCC

through an internal switch with an on-resistance of RLP

(Figure 6). VCC then charges the load with a probe current

limited at ≈200mA.

IPROBE = (VCC - VOUT)/(RLP + RSC) (Figure 1)

If the load voltage does not reach VLP,TH (0.2V typ) within

tLP, a short-circuit fault is detected and the startup mode

is terminated according to the selected fault-management

mode (see the Latched and Autoretry Fault Management

section and Figure 5). If no fault condition is present,

PGOOD/PGOOD asserts at the end of the startup period

(see the Turn-On Waveforms in the Typical Operating

Characteristics).

Load probing can only be, and must be, employed when

not using an external RSENSE.

Normal Operation

In normal operation, after startup is complete, protection

is provided by turning off the external MOSFET when a

fault condition is encountered. Dual-speed/bilevel fault

protection incorporates two comparators with different

thresholds and response times to monitor the current:

1) Slow comparator. This comparator has a 1.6ms (typ)

response time. The slow comparator ignores low-

amplitude momentary current glitches. After an extended

overcurrent condition, a fault is acknowledged and the

MOSFET gate is discharged.

2) Fast comparator. This comparator has a quick

response time and a higher threshold voltage. The fast

comparator turns off the MOSFET immediately when

it detects a large high-current event such as a short

circuit.

In each case, when a fault is encountered, the power-

good output deasserts and the device drives GATE low.

After a fault, the MAX5924A, MAX5924B, MAX5925A,

and MAX5925B latch GATE low and the MAX5924C,

MAX5924D, MAX5925C, and MAX5925D enter the

autoretry mode. The MAX5926 has selectable latched

Figure 5. Startup Waveform

Figure 6. Load-Probe Resistance vs. Supply Voltage Figure 7. Slow Comparator Response to an Overcurrent Fault

tPROBE < tLP

IINRUSH

= LARGE

= SMALL

OUT

LOAD

PROBE

LP,TH

(0.2V typ)

SR = dV

= SMALL

SR = dV

VCC (V)

RLP (Ω)

1210864

2 14

VCC = VS

GATE

PGOOD*

OUT

LOAD

LIM

3.0V TO 6.7V

PGOOD**

*MAX5924B, MAX5924D, MAX5925B, MAX5925D, AND MAX5926 ONLY.

**MAX5924A, MAX5924C, MAX5925A, MAX5925C, AND MAX5926 ONLY.

CBS

THPGOOD

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

or autoretry modes. Figure 7 shows the slow comparator

response to an overcurrent fault.

Bilevel Fault Protection

Bilevel Fault Protection in Startup Mode

Bilevel fault protection is disabled in startup mode, and is

enabled when VGATE-VOUT exceeds VCB,EN at the end

of the startup period.

When no RSENSE is detected, neither slow nor fast

comparator is active during startup because the high

RD(ON) of the MOSFET when not fully enhanced would

signal an artificially-high VIN-VSENSE voltage. Load

probing prior to startup insures that the output is not short-

circuited.

When RSENSE is detected, the slow comparator is

disabled during startup while the fast comparator remains

active. The overcurrent trip level is higher than normal

during the startup period because the ICB is temporarily

doubled to ICB,SU at this time. This allows higher than

normal startup current to allow for output capacitor

charging current.

Slow Comparator

The slow comparator is disabled during startup while the

external MOSFET turns on.

If the slow comparator detects an overload condition

while in normal operation (after startup is complete), it

turns off the external MOSFET by discharging the gate

capacitance with IGATE,PD. The magnitude of IGATE,PD

depends on the external MOSFET gate-to-source voltage

(VGS). The discharge current is strongest immediately

following a fault and decreases as the MOSFET gate is

discharged (Figure 8a).

Figure 8a. Gate Discharge Current vs. MOSFET Gate-to-Source

Voltage

Table 1. Selecting Fault Management

Mode (MAX5926)

LATCH FAULT MANAGEMENT

Low Autoretry mode

High Latched mode

VGS (V)

IGATE, PD (mA)

5 62 3 4

0 7

VCC = 13.2V

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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Fast Comparator

The fast comparator is used for serious current overloads

or short circuits. If the load current reaches the fast com-

parator threshold, the device quickly forces the MOSFET

off. The fast comparator has a response time of 280ns,

and discharges GATE with IGATE,PD (Figure 8a). The fast

comparator is disabled during startup when no RSENSE

is detected

Latched and Autoretry Fault Management

The MAX5924A, MAX5924B, MAX5925A, and MAX5925B

latch the external MOSFET off when an overcurrent fault is

detected. Following an overcurrent fault, the MAX5924C,

MAX5924D, MAX5925C, and MAX5925D enter autoretry

mode. The MAX5926 can be configured for either latched

or autoretry mode (see Table 1).

In autoretry, a fault turns the external MOSFET off then

automatically restarts the device after the autoretry delay,

tRETRY. During the autoretry delay, pull EN or EN1 low to

restart the device. In latched mode, pull EN or EN1 low for

at least 100μs to clear a latched fault and restart the device.

Power-Good Outputs

The power-good output(s) are open-drain output(s) that

deassert:

●When VCC < VUVLO

●During tD,UVLO

●When VGS < VTHPGOOD

●During load probing

●When disabled (EN = GND (MAX5924/MAX5925),

EN1 = GND or EN2 = high (MAX5926))

●During fault management

●During tRETRY or when latched off (MAX5924A,

MAX5924B, MAX5925A, MAX5925B, or MAX5926

(LATCH = low)).

PGOOD/PGOOD asserts only if the part is in normal

mode and no faults are present.

Undervoltage Lockout (UVLO)

UVLO circuitry prevents the devices from turning on the

external MOSFET until VCC exceeds the UVLO thresh-

old, VUVLO, for tD,UVLO. UVLO protects the external

MOSFET from insufficient gate-drive voltage, and tD,UVLO

ensures that the board is fully plugged into the backplane

and VCC is stable prior to powering the hot-swapped

system. Any input voltage transient at VCC below the

UVLO threshold for more than the UVLO deglitch period

(tDG) resets the device and initiates a startup sequence.

Device operation is protected from momentary input-

voltage steps extending below the UVLO threshold for a

deglitch period, tDG. However, the power-good output(s)

may momentarily deassert if the magnitude of a negative

step in VCC exceeds approximately 0.5V, and VCC drops

below VUVLO. Operation is unaffected and the power-good

output(s) assert(s) within 200μs, as shown in Figure 8b. This

figure also shows that if the UVLO condition exceeds tDG =

900μs (typ), the power-good output(s) again deassert(s)

and the load is disconnected.

Determining Inrush Current

Determining a circuit’s inrush current is necessary to

choose a proper MOSFET. The MAX5924/MAX5925/

MAX5926 regulate the inrush current by controlling the

output-voltage slew rate, but inrush current is also a function

of load capacitance. Determine an anticipated inrush current

using the following equation:

OUT

INRUSH L L

I (A ) C C SR

dt 1000

= = ×

Figure 8b. PGOOD Behavior with Large Negative Input-Voltage

Step when VS is Near VS(MIN)

Figure 9. Impact of CGATE on the VGATE Waveform

2V/div

1V/div

200µs/div

GATE

PGOOD

VCC 5V/div

VGATE

VS = VCC = 13.2V

CSLEW = 1µF

CL = 10µF

10ms/div

MOSFET ONLY

MOSFET AND

CGATE = 20nF

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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│

where CL is the load capacitance in μF and SR is the

selected device output slew rate in V/ms. For example,

assuming a load capacitance of 100μF and using the

value of SR = 10V/ms, the anticipated inrush current

is 1A. If a 16V/ms output slew rate is used, the inrush

current increases to 1.6A. Choose SR so the maximum

anticipated inrush current does not trip the fast circuit-

breaker comparator during startup.

Slew Rate

The MAX5924/MAX5925/MAX5926 limit the slew rate of

VOUT. Connect an external capacitor, CSLEW, between

SLEW and GND to adjust the slew-rate limit. Floating

SLEW sets the maximum slew rate to the minimum value.

Calculate CSLEW using the following equation:

CSLEW = 330 10-9 / SR

where, SR is the desired slew rate in V/ms and CSLEW

is in nF.

This equation is valid for CSLEW ≥ 100nF. For higher SR,

see the Typical Operating Characteristics.

A 2μA (typ) pullup current clamped to 1.4V causes an

initial jump in the gate voltage, VGATE, if CGATE is small

and the slew rate is slow (Figure 3). Figure 9 illustrates

how the addition of gate capacitance minimizes this initial

jump. CGATE should not exceed 25nF.

EN (MAX5924/MAX5925), EN1/EN2 (MAX5926)

The enable comparators control the on/off function of the

MAX5924/MAX5925/MAX5926. Enable is also used to

reset the fault latch in latch mode. Pull EN or EN1 low for

100μs to reset the latch. A resistive divider between EN or

EN1, VS, and GND sets the programmable turn-on voltage

to a voltage greater than VUVLO (Figure 10).

Selecting a Circuit-Breaker Threshold

The MAX5924/MAX5925/MAX5926 offer a circuit-breaker

function to protect the external MOSFET and the load

from the potentially damaging effects of excessive current.

As load current flows through RDS(ON) (Figure 12) or

RSENSE (Figure 13), a voltage drop is generated. After

VGS exceeds VCB,EN, the MAX5924/MAX5925/MAX5926

monitor this voltage to detect overcurrent conditions. If

this voltage exceeds the circuit-breaker threshold, the

Figure 11. Maximum Circuit-Breaker Programming Resistor vs. Temperature

Figure 10. Adjustable Turn-On Voltage

EN (EN1)

SENSE

GATE

+ R

) V

EN/UVLO

( ) ARE FOR MAX5926 ONLY.

OUT

SC_DET

(EN2)

GND

S,TURN-ON

MAX5924_

MAX5925_

MAX5926

TEMPERATURE (°C)

RCB(MAX) (Ω)

603510-15

3000

6000

9000

12,000

15,000

-40 85

VS = 1.5V

VS = 1.4V

VS = 1.3V

VS = 1.2V

VS = 1.1V

VS = 1.0V

TC = 0ppm/°C

TEMPERATURE (°C)

RCB(MAX) (Ω)

603510-15

3000

6000

9000

12,000

15,000

-40 85

VS = 1.5V

VS = 1.4V

VS = 1.3V

VS = 1.2V

VS = 1.1V

VS = 1.0V

TC = 3300ppm/°C

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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external MOSFET turns off and the power-good output(s)

deassert(s). To accommodate different MOSFETs, sense

resistors, and load currents, the MAX5924/MAX5925/

MAX5926 voltage across RCB can be set between 10mV

and 500mV. The value of the circuit-breaker voltage must

be carefully selected based on VS (Figure 11).

No RSENSE Mode

When operating without RSENSE, calculate the circuit-

breaker threshold using the MOSFET’s RDS(ON) at the

worst possible operating condition, and add a 20% overcurrent

margin to the maximum circuit current. For example, if a

MOSFET has an RDS(ON) of 0.06Ω at TA = +25°C, and a

normalized on-resistance factor of 1.75 at TA = +105°C,

the RDS(ON) used for calculation is the product of these

two numbers, or (0.06Ω) x (1.75) = 0.105Ω. Then, if the

maximum current is expected to be 2A, using a 20%

margin, the current for calculation is (2A) x (1.2) = 2.4A.

The resulting minimum circuit-breaker threshold is then a

product of these two numbers, or (0.105Ω) x (2.4A) = 0.252V.

Using this method to choose a circuit-breaker threshold

allows the circuit to operate under worst-case conditions

without causing a circuit-breaker fault, but the circuit-

breaker function will still detect a short circuit or a gross

overcurrent condition.

To determine the proper circuit-breaker resistor value use

the following equation, which refers to Figure 12:

( )

(T)

TRIPSLOW DS(ON) CB,OS

I xR V

where ITRIPSLOW is the desired slow-comparator trip

current.

The fast-comparator trip current is determined by the

selected RCB value and cannot be adjusted independently.

The fast-comparator trip current is given by:

( )

CB CB

CBF CB,OS

TRIPFAST (T)

DS(ON)

I xR R V

+±

SC_DET must be connected to OUT through the selected

RSC when not using RSENSE.

RSENSE Mode

When operating with RSENSE, calculate the circuit-breaker

threshold using the worst possible operating conditions,

and add a 20% overcurrent margin to the maximum circuit

current. For example, with a maximum expected current

of 2A, using a 20% margin, the current for calculation

is (2A) x (1.2) = 2.4A. The resulting minimum circuit-

Figure 12. Circuit Breaker Using RDS(ON) Figure 13. Circuit Breaker Using RSENSE

SELECT

SLOW

COMPARATOR

VCB,TH

ICB

MAX5925

MAX5926

CB SENSE

GATE

RCB

ILOAD

RCBF

RDS(ON)

CB,OS

VOUT

OUT

FAST

COMPARATOR

VCBF,TH

CB,OS

SELECT

ICB

MAX5925

MAX5926

SENSE GATE

RCB

ILOAD

RCBF

RSENSE

VOUT

OUT

SLOW

COMPARATOR

VCB,TH

VCB,OS

FAST

COMPARATOR

VCBF,TH

VCB,OS

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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│

breaker threshold is then a product of this current and

RSENSE = 0.06Ω, or (0.06Ω) x (2.4A) = 0.144V. Using

this method to choose a false circuit-breaker threshold

allows the circuit to operate under worst-case conditions

without causing a circuit-breaker fault, but the circuit-

breaker function will still detect a short-circuit or a gross

overcurrent condition.

To determine the proper circuit-breaker resistor value, use

the following equation, which refers to Figure 13:

( )

TRIPSLOW SENSE OS

CB,

I xR V

where, ITRIPSLOW is the desired slow-comparator trip

current.

The fast-comparator trip current is determined by the

selected RCB value and cannot be adjusted independently.

The fast-comparator trip current is given by:

( )

CB CB

CBF CB,OS

TRIPFAST

SENSE

I xR R V

+±

SC_DET should be connected to VCC when using

RSENSE.

Circuit-Breaker Temperature Coefcient

In applications where the external MOSFET’s on-resistance

is used as a sense resistor to determine overcurrent

conditions, a 3300ppm/°C temperature coefficient is

desirable to compensate for the RDS(ON) temperature

coefficient. Use the MAX5926’s TC input to select the

circuit-breaker programming current’s temperature coefficient,

TCICB (see Table 2). The MAX5924 temperature coefficient

is preset to 0ppm/°C, and the MAX5925’s is preset to

3300ppm/°C.

Setting TCICB to 3300ppm/°C allows the circuit-breaker

threshold to track and compensate for the increase in

the MOSFET’s RDS(ON) with increasing temperature.

Most MOSFETs have a temperature coefficient within a

3000ppm/°C to 7000ppm/°C range. Refer to the MOSFET

data sheet for a device-specific temperature coefficent.

RDS(ON) and ICB are temperature dependent, and can

therefore be expressed as functions of temperature. At a

given temperature, the MAX5925/MAX5926 indicate an

overcurrent condition when:

ITRIPSLOW x RDS(ON)(T) ≥ ICB(T) x RCB + |VCB,OS|

where VCB,OS is the worst-case offset voltage. Figure 14

graphically portrays operating conditions for a MOSFET

with a 4500ppm/°C temperature coefficient.

Applications Information

Component Selection

nMOSFET

Most circuit component values may be calculated with

the aid of the devices. The “Design calculator for choosing

component values” software can be downloaded from the

MAX5924–MAX5926 Quickview on the Maxim website.

Figure 14. Circuit-Breaker Trip Point and Current-Sense

Voltage vs. Temperature

Table 2. Programming the Temperature

Coefficient (MAX5926)

Table 3. Suggested External MOSFETs

TC TCICB (ppm/°C)

High 0

Low 3300

APPLICATION

CURRENT (A) PART DESCRIPTION

1International Rectier

IRF7401 SO-8

2 Siliconix Si4378DY SO-8

5Siliconix SUD40N02-06 DPAK

10 Siliconix SUB85N02-03 D2PAK

TEMPERATURE (°C)

VCB AND VSENSE (mV)

85603510-15

-40 110

= V

= 13.2V, R

= 672Ω, I

TRIPSLOW

= 5A,

DS(ON)

(25) = 6.5mΩ

CIRCUIT-BREAKER TRIP REGION

SENSE

)

VCB = ICB(T) x RCB + VCB,OS

(3300ppm/°C)

SENSE

= R

DS(ON)

(T) x I

LOAD(MAX)

(4500ppm/°C)

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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│

Select the external nMOSFET according to the

application’s current and voltage level. Table 3 lists some

recommended components. Choose the MOSFET’s on-

resistance, RDS(ON), low enough to have a minimum

voltage drop at full load to limit the MOSFET power

dissipation. High RDS(ON) can cause undesired power

loss and output ripple if the board has pulsing loads or

triggers an external undervoltage reset monitor at full

load. Determine the device power-rating requirement to

accommodate a short circuit on the board at startup with

the device configured in autoretry mode.

Using the devices in latched mode allows the consideration

of MOSFETs with higher RDS(ON) and lower power ratings.

A MOSFET can typically withstand single-shot pulses with

higher dissipation than the specified package rating. Low

MOSFET gate capacitance is not necessary since the

inrush current limiting is achieved by limiting the gate dv/

dt. Table 4 lists some recommended manufacturers and

components.

Be sure to select a MOSFET with an appropriate gate drive

(see the Typical Operating Characteristics). Typically, for

VCC less than 3V, select a 2.5V VGS MOSFET.

Optional Sense Resistor

Select the sense resistor in conjunction with RCB to

set the slow and fast circuit-breaker thresholds (see

the Selecting a Circuit-Breaker Threshold section). The

sense-resistor power dissipation depends on the device

configuration. If latched mode is selected, PRSENSE =

(IOVERLOAD)2 x RSENSE; if autoretry is selected, then

PRSENSE = (IOVERLOAD)2 x RSENSE x (tON/tRETRY).

Choose a sense-resistor power rating of twice the

PRSENSE for long-term reliable operation. In addition,

ensure that the sense resistor has an adequate I2T rating

to survive instantaneous short-circuit conditions.

No-Load Operation

The internal circuitry is capable of sourcing a current at the

OUT terminal of up to 120μA from a voltage VIN + VGS.

If there is no load on the circuit, the output capacitor will

charge to a voltage above VIN until the external MOSFET’s

body diode conducts to clamp the capacitor voltage at VIN

plus the body-diode VF. When testing or operating with no

load, it is therefore recommended that the output capacitor

be paralleled with a resistor of value:

R = VX/120μA

where VX is the maximum acceptable output voltage prior

to hot-swap completion.

Design Procedure

Given:

●VCC = VS = 5V

●CL = 150μF

●Full-Load Current = 5A

●No RSENSE

●IINRUSH = 500mA

Procedures:

1) Calculate the required slew rate and corresponding CSLEW:

INRUSH

SR 3.3

1000 C ms

= =

SLEW V

330 10 330 10

C 0 . 1µ F

SR 3.3

−−

××

===

2) Select a MOSFET and determine the worst-case

power dissipation.

3) Minimize power dissipation at full load current and

at high temperature by selecting a MOSFET with an

appropriate RDS(ON). Assume a 20°C temperature

difference between the devices and the MOSFET.

For example, at room temperature the IRF7822’s

RDS(ON) = 6.5mΩ. The temperature coefficient for this

device is 4000ppm/°C. The maximum RDS(ON) for the

MOSFET at TJ(MOSFET) = +105°C is:

DS(ON)105

ppm

R 6.5m 1 (105 C 25 C) 4000 C

8.58m



= Ω× + ° − ° ×





= Ω

Table 4. Component Manufacturers

COMPONENT MANUFACTURER PHONE WEBSITE

Sense Resistors Dale-Vishay 402-564-3131 www.vishay.com

IRC 828-264-8861 www.irctt.com

MOSFETs Fairchild 888-522-5372 www.fairchildsemi.com

International Rectier 310-233-3331 www.irf.com

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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│

The power dissipation in the MOSFET at full load is:

P I R (5A) 8.58m 215mW= = × Ω=

4) Select RCB.

Since the MOSFET’s temperature coefficient

is 4000ppm/°C, which is greater than TCICB

(3300ppm/°C), calculate the circuit-breaker threshold

at high temperature so the circuit breaker is guaran-

teed not to trip at lower temperature during normal

operation (Figure 15).

ITRIPSLOW = IFULL LOAD + 20% = 5A + 20% = 6A

RDS(ON)105 = 8.58mΩ (max), from step 2

ICB85 = 58μA x (1 + (3300ppm/°C x (85 - 25)°C)

= 69.5μA (min)

( )

TRIPSLOW DS(ON)105 CB,OS

CB85

I xR V

RCB = ((6A x 8.58mΩ) + 4.7mV)/69.5μA = 808Ω

Layout Considerations

Keep all traces as short as possible and maximize the high-

current trace dimensions to reduce the effect of undesir-

able parasitic inductance. Place the MAX5924/MAX5925/

MAX5926 close to the card’s connector. Use a ground

plane to minimize impedance and inductance. Minimize the

current-sense resistor trace length (<10mm), and ensure

accurate current sensing with Kelvin connections.

When the output is short circuited, the voltage drop

across the external MOSFET becomes large. Hence, the

power dissipation across the switch increases, as does

the die temperature. An efficient way to achieve good

power dissipation on a surface-mount package is to lay

out two copper pads directly under the MOSFET pack-

age on both sides of the board. Connect the two pads to

the ground plane through vias, and use enlarged copper

mounting pads on the top side of the board.

It is important to maximize the thermal coupling between

the MOSFET and the MAX5925/MAX5926 to balance the

device junction temperatures. When the temperatures

of the two devices are equal, the circuit-breaker trip

threshold is most accurate. Keep the MOSFET and the

MAX5925/MAX5926 as close to each other as possible

to facilitate thermal coupling.

Figure 15. Kelvin Connection for the Current-Sense Resistor

SENSE RESISTOR

HIGH-CURRENT PATH

MAX5924

MAX5925

MAX5926

RCB

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

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│

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

10 µMAX U10CN+1 21-0061

10 QSOP-EP E16E-1 21-0112

PART

CIRCUIT-BREAKER

TEMPCO

(ppm/°C)

FAULT MANAGEMENT

POWER-GOOD OUTPUT

PGOOD

(OPEN-DRAIN)

PGOOD

(OPEN-DRAIN)

MAX5924A 0 Latched ü—

MAX5924B 0 Latched — ü

MAX5924C 0 Autoretry ü—

MAX5924D 0 Autoretry — ü

MAX5925A 3300 Latched ü—

MAX5925B 3300 Latched — ü

MAX5925C 3300 Autoretry ü—

MAX5925D 3300 Autoretry — ü

MAX5926 0 or 3300 (Selectable) Latched or Autoretry (Selectable) ü ü

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

www.maximintegrated.com Maxim Integrated

│

Package Information

For the latest package outline information and land patterns

(footprints), go to www.maximintegrated.com/packages. Note

that a “+”, “#”, or “-” in the package code indicates RoHS status

only. Package drawings may show a different suffix character, but

the drawing pertains to the package regardless of RoHS status.

Chip Information

TRANSISTOR COUNT: 3751

PROCESS: BiCMOS

Selector Guide

*Future product—contact factory for availability.

**EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX5924AEUB -40°C to +85°C 10 µMAX

MAX5924BEUB -40°C to +85°C 10 µMAX

MAX5924CEUB* -40°C to +85°C 10 µMAX

MAX5924DEUB* -40°C to +85°C 10 µMAX

MAX5925AEUB -40°C to +85°C 10 µMAX

MAX5925BEUB* -40°C to +85°C 10 µMAX

MAX5925CEUB* -40°C to +85°C 10 µMAX

MAX5925DEUB* -40°C to +85°C 10 µMAX

MAX5926EEE -40°C to +85°C 16 QSOP–EP**

Ordering Information

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 8/05 Initial release —

1 6/06 Revised data sheet title, General Description, Features, EC table, Typical

Operating Circuit, and added No-Load Operation section. 1–13, 15–18

2 10/06 Initial release of MAX5924BEUB and revised EC table. 1–4, 10–12

3 4/10 Revised EC table. 2–4

4 1/16

Updated Circuit-Breaker Programming Current, Circuit-Breaker Trip Gate

Pulldown Current, External Gate Drive and EN, EN1 Reference Threshold

specications of the Electrical Characteristics table.

2–3

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses

are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)

shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.

MAX5924/MAX5925/

MAX5926

1V to 13.2V, n-Channel Hot-Swap Controllers

Require No Sense Resistor

│

Revision History

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

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Maxim Integrated:

MAX5924AEUB+ MAX5924AEUB+T MAX5924BEUB+ MAX5924BEUB+T MAX5924CEUB+ MAX5924CEUB+T

MAX5924DEUB+ MAX5924DEUB+T MAX5925AEUB+ MAX5925AEUB+T MAX5925BEUB+ MAX5925BEUB+T

MAX5925CEUB+ MAX5925CEUB+T MAX5925DEUB+ MAX5925DEUB+T MAX5926EEE+ MAX5926EEE+T