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.
N
MAX5925
MAX5926
SC_DET
GND
VCC
REMOVABLE CARD
2.25V TO 13.2V
BACKPLANE
CB SENSEGATE
GND
VS
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
N
MAX5924
MAX5926
GND
VCC
REMOVABLE CARD
2.25V TO 13.2V
BACKPLANE
CB SENSE GATE
GND
VS
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
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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
V
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
V
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
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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
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
CC
(V)
VGATE - VS (V)
1210864
3
4
5
6
7
2
2 14
VS = 1V
VS = 3V
VS = 5V
VS = VCC
MAX5926 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5924 toc01
V
CC
(V)
ICC (mA)
1210864
0.4
0.8
1.2
1.6
2.0
0
2 14
VCC = VSENABLED
DISABLED
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
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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
30
40
50
60
70
80
20
-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
1
10
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
40
44
48
52
56
36
0 14
VCC = 13.2V
TC = 3300ppm/°C
TC = 0ppm/°C
CIRCUIT-BREAKER CURRENT
vs. SUPPLY VOLTAGE (TC = 3300ppm/°C)
MAX5924 toc06
VCC (V)
I
CB
(µA)
1210864
49
51
53
55
47
2 14
VCC = VS
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Maxim Integrated
│
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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
5V/div
200µs/div
0V
0V
0V
TURN-ON WAVEFORM
(CSLEW = 330nF)
MAX5924 toc11
PGOOD
OUT
GATE 5V/div
5V/div
5V/div
2ms/div
0V
0V
0V
TURN-OFF WAVEFORM
MAX5924 toc12
PGOOD
GATE
EN1 5V/div
5V/div
5V/div
2µs/div
0V
0V
0V
OVERCURRENT CIRCUIT-BREAKER EVENT
MAX5924 toc13
OUT
GATE
IFET
10V/div
5V/div
10V/div
400µs/div
0V
0V
0V
tCBS
1A/div
0A
PGOOD
SHORT-CIRCUIT CIRCUIT-BREAKER EVENT
MAX5924 toc14
OUT
GATE
IFET
5V/div
5V/div
5V/div
2µs/div
0V
0V
0V
1A/div
0A
PGOOD
AUTORETRY DELAY
MAX5924 toc15
OUT
SC_DET
EN1 5V/div
100mV/div
5V/div
400ms/div
0V
0V
0V
tRETRY
tD,UVLO
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Maxim Integrated
│
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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
0V
0V
0V
GATE 5V/div
0V
UVLO DELAY AND LOAD PROBING
MAX5924 toc17
OUT
SC_DET
EN1 5V/div
100mV/div
5V/div
40ms/div
0V
0V
0V
tLP
tD,UVLO
UVLO RESPONSE
MAX5924 toc18
VCC
GATE 2V/div
1V/div
200µs/div
0V
0V
>tDG
UVLO DEGLITCH RESPONSE
MAX5924 toc19
VCC
GATE
2V/div
1V/div
200µs/div
0V
0V
<tDG
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
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Typical Operating Characteristics (continued)
PIN
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
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1
2
3
4
5
10
9
8
7
6
CB
SENSE
OUT
GATEPGOOD (PGOOD)
EN
SC_DET
VCC
MAX5924
MAX5925
MAX
TOP VIEW
SLEW
( ) FOR THE MAX5924A, MAX5924C, MAX5925A, AND MAX5925C.
GND
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
VCC CB
SENSE
OUT
GATE
SLEW
N.C.
N.C.
TC
QSOP
SC_DET
EN1
EN2
PGOOD
GND
PGOOD
LATCH
MAX5926
EP
Pin Congurations
Pin Description
PIN
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
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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*)
EN
VCC
REMOVABLE CARD
2.25V TO 13.2V
BACKPLANE
CB
TC** LATCH**
SENSEGATE
EN (EN1**)
VS
1V TO VCC
VCC
CL
CSLEW
OUT
GND
RSC
RCB
*MAX5925A AND MAX5925C.
**MAX5926.
GND
GND
V+
EN2 EN2**
ON (ON*)
DC-DC CONVERTER
20kΩ
10Ω
1µF
MAX5924
MAX5926
SC_DET
PGOOD**
SLEW
PGOOD (PGOOD*)
EN
VCC
REMOVABLE CARD
2.25V TO 13.2V
BACKPLANE
CB
LATCH**TC**
SENSE GATE
EN (EN1**)
VS
1V TO VCC
VCC
CL
CSLEW
OUT
GND
RCB
*MAX5924A AND MAX5924C.
**MAX5926.
GND
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
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Figure 3. Functional Diagram
LOGIC
CONTROL
OSCILLATOR
TIMER
VS
VZ = 9V
N
CHARGE PUMP
EN/(EN1***)
CB
SLEW
VCC
GATE
VCC
VCC
VCC
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
A
75kΩ
75kΩ
50kΩ
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
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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:
L
INRUSH
C SR
I
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
NO
NO
NO
PGOOD
YES
NO
YES
YES
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
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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
C
L
= LARGE
C
L
= SMALL
V
OUT
V
OUT
I
LOAD
I
LOAD
I
PROBE
V
LP,TH
(0.2V typ)
SR = dV
dt
C
L
= SMALL
SR = dV
dt
VCC (V)
RLP (Ω)
1210864
6
8
10
12
14
4
2 14
VCC = VS
V
GATE
PGOOD*
V
OUT
I
LOAD
I
LIM
3.0V TO 6.7V
PGOOD**
*MAX5924B, MAX5924D, MAX5925B, MAX5925D, AND MAX5926 ONLY.
**MAX5924A, MAX5924C, MAX5925A, MAX5925C, AND MAX5926 ONLY.
t
CBS
V
THPGOOD
MAX5924/MAX5925/
MAX5926
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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
1
10
20
30
40
50
60
0
0 7
VCC = 13.2V
MAX5924/MAX5925/
MAX5926
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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
dV
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
1V/div
200µs/div
GATE
PGOOD
VCC 5V/div
VGATE
0V
0V
VS = VCC = 13.2V
CSLEW = 1µF
CL = 10µF
10ms/div
MOSFET ONLY
MOSFET AND
CGATE = 20nF
MAX5924/MAX5925/
MAX5926
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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)
CB
SENSE
GATE
V
S
R
1
R
2
(R
2
+ R
1
) V
EN/UVLO
R
2
( ) ARE FOR MAX5926 ONLY.
OUT
SC_DET
(EN2)
V
CC
GND
R
CB
V
S,TURN-ON
=
R
SC
MAX5924_
MAX5925_
MAX5926
TEMPERATURE (°C)
RCB(MAX) (Ω)
603510-15
3000
6000
9000
12,000
15,000
0
-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
0
-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
CB
CB
I xR V
R
I
+
=
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
IR
+±
=
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
TC
SELECT
SLOW
COMPARATOR
VCB,TH
ICB
MAX5925
MAX5926
CB SENSE
GATE
VS
RCB
ILOAD
RCBF
RDS(ON)
V
CB,OS
VOUT
OUT
FAST
COMPARATOR
VCBF,TH
V
CB,OS
TC
SELECT
ICB
MAX5925
MAX5926
SENSE GATE
VS
RCB
ILOAD
RCBF
RSENSE
VOUT
OUT
CB
SLOW
COMPARATOR
VCB,TH
VCB,OS
FAST
COMPARATOR
VCBF,TH
VCB,OS
MAX5924/MAX5925/
MAX5926
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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,
CB
CB
I xR V
R
I
+
=
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
IR
+±
=
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
25
30
35
40
45
50
20
-40 110
V
S
= V
CC
= 13.2V, R
CB
= 672Ω, I
TRIPSLOW
= 5A,
R
DS(ON)
(25) = 6.5mΩ
CIRCUIT-BREAKER TRIP REGION
(V
SENSE
V
CB
)
VCB = ICB(T) x RCB + VCB,OS
(3300ppm/°C)
V
SENSE
= R
DS(ON)
(T) x I
LOAD(MAX)
(4500ppm/°C)
MAX5924/MAX5925/
MAX5926
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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
L
IV
SR 3.3
1000 C ms
= =
×
99
SLEW V
ms
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
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The power dissipation in the MOSFET at full load is:
22
D
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
CB
CB85
I xR V
RI
+
=
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
www.maximintegrated.com Maxim Integrated
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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
│
21
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
© 2016 Maxim Integrated Products, Inc.
│
22
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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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