19-3443; Rev 3; 4/10
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
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
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 sup-
plies 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 operat-
ing 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 MAX5924/MAX5925/MAX5926 include many inte-
grated 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 n-channel MOSFET.
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 coef-
ficient is 0ppm/°C and the MAX5925 temperature coeffi-
cient 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
Features
oHot Swap 1V to 13.2V with VCC ≥ 2.25V
oDrive High-Side n-Channel MOSFET
oOperation With or Without RSENSE
oTemperature-Compensated RDS(ON) Sensing
oProtected During Turn-On into Shorted Load
oAdjustable Circuit-Breaker Threshold
oProgrammable Slew-Rate Control
oProgrammable Turn-On Voltage
oAutoretry or Latched Fault Management
o10-Pin µMAX®or 16-Pin QSOP Packages
MAX5924/MAX5925/MAX5926
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Typical Operating Circuits
Ordering Information
EVALUATION KIT
AVAILABLE
Selector Guide appears at end of data sheet.
Pin Configurations appear at end of data sheet.
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**
Typical Operating Circuits continued at end of data sheet.
*
Future product—contact factory for availability.
**
EP = Exposed pad.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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= 500Ωfrom OUT to GND, CL= 1µF, SLEW =
open, TA= +25°C, unless otherwise noted.) (Note 1)
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.
(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 +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER SUPPLIES
VCC Operating Range VCC 2.7 13.2 V
VS Operating Range VSVS as defined 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 D efaul t val ue, V
S
and V
C C
i ncr easi ng , Fi g ur e 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
2.7V < VCC < 5V 4 30 65
Load-Probe Resistance (Note 3) RLP 5V < VCC < 13.2V 3 10 20
Ω
Load-Probe Timeout tLP 43 102 205 ms
Load-Probe Threshold Voltage VLP,TH (Note 4) 172 200 235 mV
CIRCUIT BREAKER
VCC = 2.7V and VCB
= 1V 37
ICB TC = high
(MAX5926), MAX5924 2.7V ≤ VCC ≤ 13.2V 34 37 42
VCC = 2.7V, VCB =
1V, TA = +25°C 30 40 50
ICB25 TC = low (MAX5926),
MAX5925 (Note 5) 2.7V ≤ VCC ≤ 13.2V,
TA = +25°C 40 50 60
VCC = 2.7V and VCB
= 1V, TA = +85°C 40 50 60
Circuit-Breaker Programming
Current
ICB85 TC = low (MAX5926),
MAX5925 (Note 5) 2.7V ≤ VCC ≤ 13.2V,
TA = +85°C 50 60 70
µA
*
GATE is internally driven and clamped. Do not drive GATE with external source.
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
_______________________________________________________________________________________ 3
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= 500Ωfrom 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 13.5 27 mA
MAX5924, TC = high (MAX5926) 0
Circuit-Breaker Temperature
Coefficient TCICB MAX5925, TC = low (MAX5926) 3300 ppm/°C
OUT Current IOUT 120 µA
MOSFET DRIVER
External Gate Drive VGS VGATE - VOUT 2.7V ≤ VCC ≤ 13.2V 4.2 5.5 7.2 V
SLEW = open, CGATE = 10nF 2.19 9.5
Load Voltage Slew Rate SR CSLEW = 300nF, CGATE = 10nF (Note 8) 0.84 V/ms
Gate Pullup Current Capacity IGATE VGATE = 0V 239 µA
ENABLE COMPARATOR
EN, EN1 Reference Threshold VEN/UVLO VEN (MAX5924/MAX5925) or
VEN1 (MAX5926) rising 0.747 0.795 0.850 V
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
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC = 5V, CL= 1µF, CSLEW = 330nF, CGATE = 10nF, RL= 500Ω, Figure 1, TA= +25°C, unless otherwise noted.)
MAX5926 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5924 toc01
VCC (V)
ICC (mA)
1210864
0.4
0.8
1.2
1.6
2.0
0
214
VCC = VSENABLED
DISABLED
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
VCC (V)
VGATE - VS (V)
1210864
3
4
5
6
7
2
214
VS = 1V
VS = 3V VS = 5V
VS = VCC
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= 500Ωfrom 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 & +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.
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
VIH 2.0
Input Voltage VIL 0.4 V
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
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
_______________________________________________________________________________________
5
SLEW RATE vs. CSLEW
MAX5924 toc09
CSLEW (nF)
SLEW RATE (V/ms)
1500
1000500
1
10
100
0.1
0 2000
Typical Operating Characteristics (continued)
(VCC = 5V, CL= 1µF, CSLEW = 330nF, CGATE = 10nF, RL= 500Ω, Figure 1, TA= +25°C, unless otherwise noted.)
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)
CB (µ)
12108642
40
44
48
52
56
36
014
VCC = 13.2V
TC = 3300ppm/°C
TC = 0ppm/°C
CIRCUIT-BREAKER CURRENT
vs. SUPPLY VOLTAGE (TC = 3300ppm/°C)
MAX5924 toc06
VCC (V)
ICB (µA)
1210864
49
51
53
55
47
214
VCC = VS
CIRCUIT-BREAKER CURRENT
vs. SUPPLY VOLTAGE (TC = 0ppm/°C)
MAX5924 toc07
VCC (V)
ICB (µA)
1210864214
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
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
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
6 _______________________________________________________________________________________
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 = 330nF)
MAX5924 toc11
PGOOD
OUT
GATE 5V/div
5V/div
5V/div
2ms/div
0V
0V
0V
TURN-ON WAVEFORM
(CSLEW = OPEN)
MAX5924 toc10
PGOOD
OUT
GATE 5V/div
5V/div
5V/div
200µs/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
MAX5924/MAX5925/MAX5926
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
Typical Operating Characteristics (continued)
(VCC = 5V, CL= 1µF, CSLEW = 330nF, CGATE = 10nF, RL= 500Ω, Figure 1, TA= +25°C, unless otherwise noted.)
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
_______________________________________________________________________________________
7
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
8 _______________________________________________________________________________________
Pin Description
PIN
MAX5924A/
MAX5924C/
MAX5925A/
MAX5925C
MAX5924B/
MAX5924D/
MAX5925B/
MAX5925D
MAX5926 NAME
FUNCTION
111V
CC 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).
222
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.
33—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
—47
PGOOD
Open-Drain Active-High Power-Good Output
5 5 5 GND Ground
6612
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.
7713
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.
9915
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.
— — 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.
——6EN2
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.
——9TC
Circuit-Breaker Temperature Coefficient Selection Input. Drive TC low to select
a 3300ppm/°C temperature coefficient. Drive TC high to select a 0ppm/°C
temperature coefficient.
— — 10, 11 N.C. No Connection. Not internally connected.
— — EP EP Exposed Pad. Connect EP to GND.
MAX5924/MAX5925/MAX5926
Figure 1. Typical Operating Circuit (Without RSENSE)
Figure 2. Typical Operating Circuit (With RSENSE)
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
_______________________________________________________________________________________ 9
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
10 ______________________________________________________________________________________
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
Figure 3. Functional Diagram
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
______________________________________________________________________________________ 11
Detailed Description
The MAX5924/MAX5925/MAX5926 are hot-swap con-
troller 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 pro-
tection. This is achieved using an external n-channel
MOSFET 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 fac-
tory-preset features and parameters.
Startup Mode
It is important that both VCC and VSrise 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 condi-
tions 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 man-
aged according to the selected fault management
mode (see the
Latched and Auto-Retry Fault
Management
section).
If load probing (see the
Load Probing
section) is suc-
cessful, 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 compara-
tor 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:
where SR is the slew rate in V/ms and CLis load capac-
itance 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 MAX5924/
MAX5925/MAX5926 enable standard bilevel fault pro-
tection with normal ICB (see the
Bilevel Fault Protection
section).
ICSR
INRUSH L
=×
1000
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
Figure 4. Startup Flow Chart
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
12 ______________________________________________________________________________________
Load Probing
The MAX5924/MAX5925/MAX5926 load-probing circuit-
ry 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 start-
up mode is terminated according to the selected fault-
management mode (see the
Fault Management
section
and Figure 5). If no fault condition is present,
PGOOD/PGOOD asserts at the end of the startup peri-
od (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, protec-
tion 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 acknowl-
edged 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 or
autoretry modes. Figure 7 shows the slow comparator
response to an overcurrent fault.
VCC (V)
RLP (Ω)
1210864
6
8
10
12
14
4
214
VCC = VS
Figure 6. Load-Probe Resistance vs. Supply Voltage
VGATE
PGOOD*
VOUT
ILOAD
ILIM
3.0V TO 6.7V
PGOOD**
*MAX5924B, MAX5924D, MAX5925B, MAX5925D, AND MAX5926 ONLY.
**MAX5924A, MAX5924C, MAX5925A, MAX5925C, AND MAX5926 ONLY.
tCBS
VTHPGOOD
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
Figure 5. Startup Waveform
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
______________________________________________________________________________________ 13
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 com-
parator 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 prob-
ing prior to startup insures that the output is not short cir-
cuited.
When RSENSE is detected, the slow comparator is dis-
abled 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 capaci-
tance with IGATE,PD. The magnitude of IGATE,PD
depends on the external MOSFET gate-to-source volt-
age, VGS. The discharge current is strongest immedi-
ately following a fault and decreases as the MOSFET
gate is discharged (Figure 8a).
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.
VGS (V)
IGATE, PD (mA)
56234
1
10
20
30
40
50
60
0
07
VCC = 13.2V
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
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
14 ______________________________________________________________________________________
Undervoltage Lockout (UVLO)
UVLO circuitry prevents the MAX5924/MAX5925/
MAX5926 from turning on the external MOSFET until VCC
exceeds the UVLO threshold, 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 ini-
tiates 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 approxi-
mately 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:
where CLis the load capacitance in µF and SR is the
selected MAX5924/MAX5925/MAX5926 output slew rate
in V/ms. For example, assuming a load capacitance of
100µF and using the value of SR = 10V/ms, the anticipat-
ed 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 ini-
tial jump. CGATE should not exceed 25nF.
IAC
dV
dt CSR
INRUSH L OUT L
() =×=×
1000
5V/div
VGATE
0V
0V
VS = VCC = 13.2V
CSLEW = 1µF
CL = 10µF
10ms/div
MOSFET ONLY
MOSFET AND
CGATE = 20nF
Figure 9. Impact of C
GATE
on the V
GATE
Waveform
2V/div
1V/div
1V/div
200µs/div
GATE
PGOOD
VCC
Figure 8b. PGOOD Behavior with Large Negative Input-Voltage
Step when VSis Near VS(MIN)
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
______________________________________________________________________________________ 15
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-break-
er function to protect the external MOSFET and the load
from the potentially damaging effects of excessive cur-
rent. 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 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 R
SENSE
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% over-
current margin to the maximum circuit current. For exam-
ple, if a MOSFET has an RDS(ON) of 0.06Ωat 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-break-
er 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.
Figure 11. Maximum Circuit-Breaker Programming Resistor vs. Temperature
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
EN (EN1)
CB
SENSE
GATE
V
S
MAX5924_
MAX5925_
MAX5926
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
Figure 10. Adjustable Turn-On Voltage
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
16 ______________________________________________________________________________________
To determine the proper circuit-breaker resistor value
use the following equation, which refers to Figure 12:
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 indepen-
dently. The fast-comparator trip current is given by:
SC_DET must be connected to OUT through the select-
ed RSC when not using RSENSE.
R
SENSE
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 cur-
rent for calculation is (2A) x (1.2) = 2.4A. The resulting
minimum circuit-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:
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 indepen-
dently. The fast-comparator trip current is given by:
SC_DET should be connected to VCC when using
RSENSE.
IIxR R V
R
TRIPFAST CB CBF CB CB OS
SENSE
=+
()
±,
RIxRV
I
CB
TRIPSLOW SENSE CB OS
CB
=
()
+ ,
IIxR R V
R
TRIPFAST CB CBF CB CB OS
DS ON T
=+
()
±,
()
()
RIxR V
I
CB TRIPSLOW DS ON TCB OS
CB
=
()
+
()
() ,
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
Figure 13. Circuit Breaker Using RSENSE
TC
SELECT
SLOW
COMPARATOR
VCB,TH
ICB
MAX5925
MAX5926
CB SENSE
GATE
VS
RCB
ILOAD
RCBF
RDS(ON)
VCB,OS
VOUT
OUT
FAST
COMPARATOR
VCBF,TH
VCB,OS
Figure 12. Circuit Breaker Using RDS(ON)
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
______________________________________________________________________________________ 17
Circuit-Breaker Temperature Coefficient
In applications where the external MOSFET’s on-resis-
tance is used as a sense resistor to determine overcur-
rent conditions, a 3300ppm/°C temperature coefficient
is desirable to compensate for the RDS(ON) tempera-
ture coefficient. Use the MAX5926’s TC input to select
the circuit-breaker programming current’s temperature
coefficient, TCICB (see Table 2). The MAX5924 temper-
ature 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
n-Channel MOSFET
Most circuit component values may be calculated with
the aid of the MAX5924–MAX5926. The "Design calcula-
tor for choosing component values" software can be
downloaded from the MAX5924–MAX5926 Quickview on
the Maxim website.
Select the external n-channel MOSFET 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 dis-
sipation. 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 MAX5924/MAX5925/MAX5926 in latched mode
allows the consideration of MOSFETs with higher RDS(ON)
and lower power ratings. A MOSFET can typically with-
stand single-shot pulses with higher dissipation than the
specified package rating. Low MOSFET gate capaci-
tance 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.
Table 2. Programming the Temperature
Coefficient (MAX5926)
TC TCICB (ppm/°C)
High 0
Low 3300
Table 3. Suggested External MOSFETs
APPLICATION
CURRENT (A) PART DESCRIPTION
1International Rectifier
IRF7401 SO-8
2 Siliconix Si4378DY SO-8
5 Siliconix 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
VS = VCC = 13.2V, RCB = 672Ω, ITRIPSLOW = 5A,
RDS(ON)(25) = 6.5mΩ
CIRCUIT-BREAKER TRIP REGION
(VSENSE ≥ VCB)
VCB = ICB(T) x RCB + VCB,OS
(3300ppm/°C)
VSENSE = RDS(ON)(T) x ILOAD(MAX)
(4500ppm/°C)
Figure 14. Circuit-Breaker Trip Point and Current-Sense
Voltage vs. Temperature
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
18 ______________________________________________________________________________________
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)2x RSENSE; if autoretry is selected, then
PRSENSE = (IOVERLOAD)2x 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 MOS-
FET’s body diode conducts to clamp the capacitor volt-
age 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 VXis 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:
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 MAX5924/MAX5925/
MAX5926 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:
The power dissipation in the MOSFET at full load is:
4) Select RCB.
Since the MOSFET’s temperature coefficient is
4000ppm/°C, which is greater than TCICB
(3300ppm/°C), calculate the circuit-breaker thresh-
old at high temperature so the circuit breaker is
guaranteed 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)
RCB = ((6A x 8.58mΩ) + 4.7mV)/69.5µA = 808Ω
R
IxR V
I
CB
TRIPSLOW DS ON CB OS
CB
=
()
+
() ,105
85
PIR A m mW
D== × Ω=
22
5 8 58 215() .
RmCC
ppm
C
m
DS ON() . ( )
.
105 6 5 1 105 25 4000
858
=×+°−°×
°
⎛
⎝
⎜⎞
⎠
⎟
=Ω
Ω
CSR F
SLEW V
ms
=×=×=
−−
330 10 330 10
33
01
99
.
.µ
SR I
C
V
ms
INRUSH
L
=×=
1000 33
.
Table 4. Component Manufacturers
COMPONENT MANUFACTURER PHONE WEBSITE
Dale-Vishay 402-564-3131 www.vishay.com
Sense Resistors IRC 828-264-8861 www.irctt.com
Fairchild 888-522-5372 www.fairchildsemi.com
MOSFETs International Rectifier 310-233-3331 www.irf.com
Layout Considerations
Keep all traces as short as possible and maximize the
high-current trace dimensions to reduce the effect of
undesirable parasitic inductance. Place the MAX5924/
MAX5925/MAX5926 close to the card’s connector. Use
a ground plane to minimize impedance and induc-
tance. 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.
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
______________________________________________________________________________________ 19
SENSE RESISTOR
HIGH-CURRENT PATH
MAX5924
MAX5925
MAX5926
RCB
Figure 15. Kelvin Connection for the Current-Sense Resistor
Selector Guide
POWER-GOOD OUTPUT
PART
CIRCUIT-BREAKER
TEMPCO
(ppm/°C)
FAULT MANAGEMENT PGOOD
(OPEN-DRAIN)
PGOOD
(OPEN-DRAIN)
MAX5924A 0 Latched ✓—
MAX5924B 0 Latched — ✓
MAX5924C 0 Autoretry ✓—
MAX5924D 0 Autoretry — ✓
MAX5925A 3300 Latched ✓—
MAX5925B 3300 Latched — ✓
MAX5925C 3300 Autoretry ✓—
MAX5925D 3300 Autoretry — ✓
MAX5926 0 or 3300 (Selectable) Latched or Autoretry (Selectable) ✓✓
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
20 ______________________________________________________________________________________
1
2
3
4
5
10
9
8
7
6
CB
SENSE
OUT
GATEPGOOD (PGOOD)
EN
SC_DET
VCC
MAX5924
MAX5925
µMAX
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 Configurations
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
Typical Operating Circuits
(continued)
Chip Information
TRANSISTOR COUNT: 3751
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a "+", "#", or "-"
in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the draw-
ing pertains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
10 µMAX U10CN+1 21-0061
16 QSOP-EP E16E-1 21-0112
MAX5924/MAX5925/MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
21
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
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