MAX5924DEUB+T [MAXIM]
Power Supply Management Circuit, Adjustable, 1 Channel, BICMOS, PDSO10, ROHS COMPLIANT, MO-187CBA, MICRO MAX, PACKAGE-10;
| 型号： | MAX5924DEUB+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Management Circuit, Adjustable, 1 Channel, BICMOS, PDSO10, ROHS COMPLIANT, MO-187CBA, MICRO MAX, PACKAGE-10 信息通信管理 光电二极管 |
| 文件： | 总22页 (文件大小：1609K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
General Description
Benefits and Features
● Hot Swap 1V to 13.2V with V
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
≥ 2.25V
CC
● Drive High-Side nMOSFET
● Operation With or Without R
SENSE
● Temperature-Compensated R
Sensing
voltage, V , is at or above 2.25V and the hot-swapped
DS(ON)
CC
supply, V , does not exceed V
.
S
CC
● Protected During Turn-On into Shorted Load
● Adjustable Circuit-Breaker Threshold
● Programmable Slew-Rate Control
● Programmable Turn-On Voltage
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.
● Autoretry or Latched Fault Management
®
● 10-Pin μMAX or 16-Pin QSOP Packages
Typical Operating Circuits
TYPICAL OPERATION WITHOUT R
SENSE
BACKPLANE
REMOVABLE CARD
N
V
OUT
1V TO V
CC
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.
V
S
2.25V TO 13.2V
V
CC
R
CB
R
SC
OUT
CB
GATE SENSE
SC_DET
V
The MAX5924/MAX5925/MAX5926 are available with
open-drain PGOOD and/or PGOOD outputs. The
MAX5925/MAX5926 also feature a circuit breaker
CC
MAX5925
MAX5926
GND
GND
with temperature-compensated R
sensing. The
DS(ON)
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).
SEE FIGURE 1 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITHOUT R
.
SENSE
TYPICAL OPERATION WITH R
SENSE
BACKPLANE
REMOVABLE CARD
R
SENSE
N
V
1V TO V
OUT
CC
V
S
2.25V TO 13.2V
V
CC
Applications
R
CB
● Base Stations
● RAID
CB
OUT
SENSE GATE
● Remote-Access Servers
● Network Routers and Switches
● Servers
V
CC
MAX5924
MAX5926
GND
GND
● Portable Device Bays
μMAX is a registered trademark of Maxim Integrated Products, Inc.
SEE FIGURE 2 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITH R
.
SENSE
Selector Guide and Ordering Information appears at end of
data sheet.
19-3443; Rev 4; 1/16
MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Absolute Maximum Ratings
(All voltages referenced to GND, unless otherwise noted.)
Continuous Power Dissipation (T = +70°C)
A
V
........................................................................-0.3V to +14V
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
CC
GATE*....................................................................-0.3V to +20V
All Other Pins ......... -0.3V to the lower of (V + 0.3V) or +14V
SC_DET Current (200ms pulse width, 15% duty cycle) ..140mA
Continuous Current (all other pins)....................................20mA
CC
*GATE is internally driven and clamped. Do not drive GATE with external source.
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
(V , EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; V (see Figure 1) = +1.05V to V ;
CC
S
CC
T
= -40°C to +85°C, unless otherwise noted. Typical values are at V
= 5V, R = 500Ω from OUT to GND, C = 1μF, SLEW = open,
A
CC
L
L
T = +25°C, unless otherwise noted.) (Note 1)
A
PARAMETER
POWER SUPPLIES
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
V
V
Operating Range
V
2.7
1.0
13.2
V
V
CC
CC
Operating Range
V
V
as defined in Figure 1
V
CC
S
S
S
Supply Current
I
FET is fully enhanced, SC_DET = V
1.5
2.5
2.47
350
mA
CC
CC
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Threshold
V
Default value, V and V
S
increasing, Figure 1
1.73
123
2.06
900
200
V
UVLO
CC
V
V
UVLO Deglitch Time
UVLO Startup Delay
t
(Note 2)
µs
ms
CC
CC
DG
D,UVLO
t
LOAD-PROBE
2.7V < V
< 5V
4
3
30
10
65
20
CC
Load-Probe Resistance (Note 3)
R
Ω
LP
5V < V
< 13.2V
CC
Load-Probe Timeout
t
43
172
102
200
205
235
ms
LP
Load-Probe Threshold Voltage
CIRCUIT BREAKER
V
(Note 4)
mV
LP,TH
V
= 2.7V and V = 1V
37
37
TC = high (MAX5926),
MAX5924
CC
CB
I
CB
2.7V ≤ V
≤ 13.2V
34
30
42
50
CC
V
= 2.7V, V
= 1V,
CC
CB
40
T
= +25°C
A
V
= 2.7V, V
CC
CB
= 1V, T = +105°C
45
60
80
TC = low
A
(MAX5925D)
I
I
(MAX5926),
MAX5925 (Note 5)
CB25
Circuit-Breaker Programming
Current
2.7V ≤ V
≤ 13.2V,
µA
CC
40
40
40
50
50
60
50
60
60
80
60
70
T
= +25°C
A
2.7V ≤ V ≤ 13.2V,
CC
T = +105°C (MAX5925D)
A
V
V
= 2.7V and
CC
CB
TC = low
(MAX5926),
MAX5925 (Note 5)
= 1V, T = +85°C
A
CB85
2.7V ≤ V
≤ 13.2V,
CC
T
= +85°C
A
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Electrical Characteristics (continued)
(V , EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; V (see Figure 1) = +1.05V to V ;
CC
S
CC
T
= -40°C to +85°C, unless otherwise noted. Typical values are at V
= 5V, R = 500Ω from OUT to GND, C = 1μF, SLEW = open,
A
CC
L
L
T = +25°C, unless otherwise noted.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
Circuit-Breaker Programming
Current During Startup
I
2 x I
µA
CB,SU
CB
Circuit-Breaker Enable Threshold
V
V
- V
, rising gate voltage (Note 6)
2.3
3.6
0.3
4.65
±4.7
V
CB,EN
GATE
OUT
Circuit-Breaker Comparator Offset
Voltage
V
mV
CB_OS
Fast Circuit-Breaker Offset
Resistor
R
Figure 3
1.2
1.9
2.7
kΩ
CBF
Slow Circuit-Breaker Delay
Fast Circuit-Breaker Delay
t
V
V
- V
- V
= 10mV
0.95
1.6
2.95
ms
ns
CBS
CB
CB
SENSE
t
= 500mV
280
CBF
SENSE
V
= 2.5V, V
= 13.2V, T = -40°C to
GATE
CC
A
13.5
12
27
27
mA
mA
+85°C
Circuit-Breaker Trip Gate Pulldown
Current
I
GATE,PD
V
= 2.5V, V
= 13.2V, T = -40°C to
GATE
CC
A
+105°C (MAX5925D)
MAX5924, TC = high (MAX5926)
MAX5925, TC = low (MAX5926)
0
Circuit-Breaker Temperature
Coefficient
TC
ppm/°C
µA
ICB
3300
OUT Current
I
120
OUT
MOSFET DRIVER
2.7V ≤ V
= -40°C to +85°C
≤ 13.2V, T
A
CC
4.2
5.5
5.5
7.2
7.2
External Gate Drive
V
V
- V
OUT
V
GS
GATE
2.7V ≤ V ≤ 13.2V,
TA = -40°C to +105°C
(MAX5925D)
CC
4.0
SLEW = open, C
= 10nF
2.19
9.5
GATE
Load Voltage Slew Rate
SR
V/ms
µA
C
= 300nF, C
= 10nF (Note 8)
0.84
SLEW
GATE
Gate Pullup Current Capacity
I
V
= 0V
239
GATE
GATE
ENABLE COMPARATOR
V
V
(MAX5924/MAX5925) or
EN
0.747
0.747
0.795 0.850
(MAX5926) rising, T = -40°C to +85°C
EN1
A
EN, EN1 Reference Threshold
V
V
EN/UVLO
V
(MAX5925D) rising,
EN
0.795 0.875
30
TA = -40°C to +105°C
EN, EN1 Hysteresis
V
mV
nA
EN,HYS
EN (MAX5924/MAX5925) = V
EN1 (MAX5926) = V
,
CC
EN, EN1 Input Bias Current
I
±8
±50
EN
CC
DIGITAL OUTPUTS (PGOOD, PGOOD)
Power-Good Output Low Voltage
V
I
= 1mA
OL
0.3
0.2
0.4
1
V
OL
Power-Good Output Open-Drain
Leakage Current
I
PGOOD/PGOOD = 13.2V
- V , rising gate voltage
µA
OH
Power-Good Trip Point
Power-Good Hysteresis
V
V
V
CB_EN
3.6
4.7
V
V
THPGOOD
GATE
OUT
V
0.36
PG,HYS
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Electrical Characteristics (continued)
(V , EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; V (see Figure 1) = +1.05V to V ;
CC
S
CC
T
= -40°C to +85°C, unless otherwise noted. Typical values are at V
= 5V, R = 500Ω from OUT to GND, C = 1μF, SLEW = open,
A
CC
L
L
T = +25°C, unless otherwise noted.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
1.6
MAX UNITS
LOGIC AND TIMING (TC, LATCH (MAX5926), EN2 (MAX5926)
Autoretry Delay
t
Autoretry mode
0.6
2.0
3.3
0.4
s
V
RETRY
V
IH
Input Voltage
V
IL
Input Bias Current
I
Logic high at 13.2V
3
µA
BIAS
MAX5924A/MAX5924B
MAX5925A/MAX5925B
MAX5926 in latched mode
Time to Clear a Latched Fault
T
200
µS
CLR
Note 1: All devices are 100% tested at T = +25°C and +85°C. All temperature limits at -40°C are guaranteed by design.
A
Note 2: V
drops 30% below the undervoltage lockout voltage during t
are ignored.
CC
DG
Note 3: R is the resistance measured between V
and SC_DET during the load-probing phase, t
.
LP
CC
LP
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 V
Supply Voltage graph in the Typical Operating Characteristics.
Note 6: See the Startup Mode section for more information.
= 2.25V to 5V. See the Circuit-Breaker Current vs.
CC
Note 7: V
is clamped to 17V (typ) above ground.
GATE
Note 8: dv/dt = 330 x 10-9/C
(V/ms), nMOS device used for measurement was IRF9530N. Slew rate is measured at the load.
SLEW
Typical Operating Characteristics
(V
= 5V, C = 1μF, C
= 330nF, C
= 10nF, R = 500Ω, Figure 1, T = +25°C, unless otherwise noted.)
CC
L
SLEW
GATE
L
A
MAX5926 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
GATE-DRIVE VOLTAGE
vs. SUPPLY VOLTAGE
MAX5926 SUPPLY CURRENT
vs. TEMPERATURE
2.0
2.4
2.0
1.6
1.2
0.8
0.4
0
7
6
5
4
3
2
V
CC
= V
S
V
= V
S
CC
ENABLED
1.6
1.2
0.8
0.4
0
V
= 13.2V
CC
V
S
= 1V
DISABLED
V
= 5.0V
CC
V
S
= V
CC
V
S
= 3V
V
= 3.0V
V
= 5V
CC
S
V
CC
= 2.25V
2
4
6
8
10
12
14
2
4
6
8
10
12
14
-40
-15
10
35
60
85
V
CC
(V)
TEMPERATURE (°C)
V
CC
(V)
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Typical Operating Characteristics (continued)
(V
= 5V, C = 1μF, C
= 330nF, C
= 10nF, R = 500Ω, Figure 1, T = +25°C, unless otherwise noted.)
CC
L
SLEW
GATE L A
CIRCUIT-BREAKER CURRENT
vs. HOT-SWAP VOLTAGE
CIRCUIT-BREAKER CURRENT
vs. SUPPLY VOLTAGE (TC = 3300ppm/°C)
GATE DRIVE VOLTAGE
vs. TEMPERATURE
56
52
48
44
40
36
55
53
51
49
47
6.0
V
CC
= V
S
V
CC
= V
S
TC = 3300ppm/°C
5.5
5.0
4.5
4.0
3.5
3.0
V
= 5.0V
CC
V
= 3.0V
CC
V
= 13.2V
CC
TC = 0ppm/°C
V
= 13.2V
12
CC
0
2
4
6
8
10
14
2
4
6
8
10
12
14
-40
-15
10
35
60
85
V
S
(V)
V
CC
(V)
TEMPERATURE (°C)
CIRCUIT-BREAKER CURRENT
vs. SUPPLY VOLTAGE (TC = 0ppm/°C)
CIRCUIT-BREAKER PROGRAMMING
CURRENT vs. TEMPERATURE
SLEW RATE vs. C
SLEW
39.4
39.2
39.0
38.8
38.6
38.4
38.2
80
70
60
50
40
30
20
100
10
1
V
CC
= V
S
V
= V = 5V
S
CC
TC = 3300ppm/°C
TC = 0ppm/°C
0.1
2
4
6
8
10
12
14
-40
-15
10
35
60
85
0
500
1000
(nF)
SLEW
1500
2000
V
(V)
TEMPERATURE (°C)
C
CC
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Typical Operating Characteristics (continued)
(V
= 5V, C = 1μF, C
= 330nF, C
= 10nF, R = 500Ω, Figure 1, T = +25°C, unless otherwise noted.)
CC
L
SLEW
GATE L A
TURN-ON WAVEFORM
(C = OPEN)
TURN-ON WAVEFORM
(C = 330nF)
SLEW
SLEW
MAX5924 toc10
MAX5924 toc11
GATE
5V/div
0V
GATE
5V/div
0V
OUT
5V/div
0V
OUT
5V/div
0V
PGOOD
5V/div
0V
PGOOD
5V/div
0V
200µs/div
2ms/div
TURN-OFF WAVEFORM
OVERCURRENT CIRCUIT-BREAKER EVENT
MAX5924 toc13
MAX5924 toc12
1A/div
EN1
5V/div
0V
I
FET
0A
t
CBS
10V/div
GATE
5V/div
0V
GATE
OUT
0V
10V/div
0V
PGOOD
5V/div
0V
5V/div
0V
PGOOD
2µs/div
400µs/div
SHORT-CIRCUIT CIRCUIT-BREAKER EVENT
AUTORETRY DELAY
MAX5924 toc14
MAX5924 toc15
I
FET
1A/div
EN1
5V/div
0V
t
D,UVLO
0A
t
RETRY
GATE
OUT
5V/div
5V/div
0V
SC_DET
OUT
0V
5V/div
0V
100mV/div
0V
5V/div
0V
PGOOD
2µs/div
400ms/div
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Typical Operating Characteristics (continued)
(V
= 5V, C = 1μF, C
= 330nF, C
= 10nF, R = 500Ω, Figure 1, T = +25°C, unless otherwise noted.)
CC
L
SLEW
GATE L A
OVERCURRENT FAULT AND
AUTORETRY DELAY
UVLO DELAY AND LOAD PROBING
MAX5924 toc16
MAX5924 toc17
EN1
EN1
5V/div
0V
5V/div
0V
GATE
5V/div
0V
t
t
LP
D,UVLO
5V/div
0V
5V/div
0V
SC_DET
OUT
SC_DET
OUT
200mV/div
0V
100mV/div
0V
400ms/div
40ms/div
UVLO RESPONSE
UVLO DEGLITCH RESPONSE
MAX5924 toc19
MAX5924 toc18
>t
DG
2V/div
GATE
GATE
2V/div
0V
<t
DG
0V
1V/div
1V/div
0V
V
CC
V
CC
0V
200µs/div
200µs/div
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Pin Configurations
TOP VIEW
V
CC
1
2
3
4
5
6
7
8
16 CB
SC_DET
EN1
15 SENSE
14 OUT
13 GATE
12 SLEW
11 N.C.
10 N.C.
V
1
2
3
4
5
10 CB
CC
SC_DET
EN
9
8
7
6
SENSE
MAX5924
MAX5925
PGOOD
GND
MAX5926
OUT
PGOOD (PGOOD)
GND
GATE
SLEW
EN2
PGOOD
LATCH
EP
MAX
9
TC
( ) FOR THE MAX5924A, MAX5924C, MAX5925A, AND MAX5925C.
QSOP
Pin Description
PIN
MAX5924A/ MAX5924B/
MAX5924C/ MAX5924D/
MAX5925A/ MAX5925B/
NAME
FUNCTION
MAX5926
MAX5925C
MAX5925D
Power-Supply Input. Connect V
to a voltage between 2.47V and 13.2V.
CC
1
1
1
V
CC
V
must always be equal to or greater than V (see Figure 1).
S
CC
Short-Circuit Detection Output. Connect SC_DET to V
through a series
OUT
resistor, R , when not using R
. SC_DET forces current (limited to
SC
SENSE
≈200mA) into the external load through R
there is a short circuit (load probing). Connect SC_DET directly to V
at startup to determine whether
SC
2
2
3
2
SC_DET
when
CC
using R
, Do not connect SC_DET to V
when not using R
in an
SENSE
SENSE
CC
attempt to disable load probing.
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
3
—
EN
V
, EN, and GND sets the programmable turn-on voltage.
CC
4
—
5
—
4
4
7
5
PGOOD Open-Drain Active-Low Power-Good Output
PGOOD Open-Drain Active-High Power-Good Output
5
GND
Ground
Slew-Rate Adjustment Input. Connect an external capacitor between SLEW
6
6
12
SLEW and GND to adjust the gate slew rate. Leave SLEW unconnected for the default
slew rate.
Gate-Drive Output. Connect GATE to the gate of the external n-channel
MOSFET.
7
8
7
8
13
14
GATE
OUT
Output Voltage. Connect OUT to the source of the external MOSFET.
Circuit-Breaker Sense Input. Connect SENSE to OUT when not using an
9
9
15
16
SENSE external R
(Figure 1). Connect SENSE to the drain of the external
SENSE
MOSFET when using an external R
(Figure 2).
SENSE
Circuit-Breaker Threshold Programming Input. Connect an external resistor,
, from CB to V to set the circuit-breaker threshold voltage.
10
10
CB
R
CB
S
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Pin Description (continued)
PIN
MAX5924A/ MAX5924B/
MAX5924C/ MAX5924D/
MAX5925A/ MAX5925B/
NAME
FUNCTION
MAX5926
MAX5925C
MAX5925D
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.
—
—
3
EN1
An optional external resistive-divider between V , EN1, and GND sets the
CC
programmable turn-on voltage while EN2 is low.
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.
—
—
—
—
—
—
6
8
9
EN2
LATCH
TC
Latch Mode Input. Drive LATCH low for autoretry mode. Drive LATCH high for
latched mode.
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
EP
N.C.
EP
No Connection. Not internally connected.
Exposed Pad. Connect EP to GND.
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
BACKPLANE
REMOVABLE CARD
1V TO V
CC
V
S
2.25V TO 13.2V
V
CC
R
SC
20kΩ
R
CB
10Ω
CB
GATE SENSE OUT
SC_DET
V+
ON (ON*)
V
CC
1µF
MAX5925
MAX5926
GND
C
L
PGOOD**
EN (EN1**)
EN
PGOOD (PGOOD*)
EN2**
EN2
GND
SLEW
GND
TC** LATCH**
C
SLEW
*MAX5925A AND MAX5925C.
**MAX5926.
DC-DC CONVERTER
Figure 1. Typical Operating Circuit (Without R
)
SENSE
BACKPLANE
REMOVABLE CARD
1V TO V
R
SENSE
CC
V
S
2.25V TO 13.2V
V
CC
20kΩ
R
CB
10Ω
10Ω
CB
SENSE GATE OUT
V+
ON (ON*)
V
CC
SC_DET
1µF
MAX5924
MAX5926
GND
C
L
PGOOD**
EN (EN1**)
EN
PGOOD (PGOOD*)
EN2**
EN2
GND
SLEW
GND
TC**
LATCH**
C
SLEW
V
CC
*MAX5924A AND MAX5924C.
**MAX5926.
DC-DC CONVERTER
Figure 2. Typical Operating Circuit (With R
)
SENSE
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
GATE
50kΩ
V
CC
CHARGE PUMP
V = 9V
Z
MAX5924
MAX5925
MAX5926
2µA
N
SLEW
A
V
CC
R
LP
N
SC_DET
OUT
V
CB,TH
CB
SLOW
COMPARATOR
V
S
75kΩ
75kΩ
TIMER
R
CBF
0.2V
V
OSCILLATOR
CBF,TH
FAST
COMPARATOR
I
TC***
CB
PGOOD*
PGOOD**
LOGIC
SENSE
CONTROL
LATCH***
V
V
CC
EN/(EN1***)
V
CC
0.8V
CC
GND
1.24V
*MAX5924B, MAX5924D, MAX5925B, MAX5925D, MAX5926 ONLY.
**MAX5924A, MAX5924C, MAX5925A, MAX5925C, MAX5926 ONLY.
***MAX5926 ONLY.
EN2***
Figure 3. Functional Diagram
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Detailed Description
V
CC
RISES ABOVE V
UVLO
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.
NO
ENABLE TRUE?
YES
FAULT MANAGEMENT
UVLO 200ms DELAY
NO
DISABLE FAULT PROTECTION,
ENABLE LOAD PROBE
R
SENSE
YES
Several critical parameters can be configured:
● Slew rate (inrush current)
PRESENT?
● Circuit-breaker threshold
● Turn-on voltage
● Fault-management mode (MAX5926)
● Circuit-breaker temperature coefficient (MAX5926)
I
= 2 x I
CB
CB,SU
NO
LOAD PROBE
DISABLE SLOW
COMPARATOR
SUCCESSFUL?
YES
See the Selector Guide for a device-specific list of factory-
preset features and parameters.
SLEW-RATE-LIMITED
STARTUP
Startup Mode
It is important that both V
rate of 100mV/ms during the critical time when power
voltages are below those values required for proper logic
and V rise at a minimum
S
CC
ENABLE STANDARD BILEVEL
FAULT PROTECTION
BEGIN NORMAL OPERATION
YES
V
V
GS CB,EN
V
NO
V
GS THPGOOD
control of internal circuitry. This applies for 0.5V ≤ V
≤
CC
PGOOD
2.5V and 0.5V ≤ V ≤ 0.8V. This is particularly true when
S
LATCH is tied high.
Figure 4. Startup Flow Chart
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 the device detects an external R
, circuit-
SENSE
breaker threshold is set at 2xI , the slow comparator
CB
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, V
rises at a rate determined by the selected slew rate (see
the Slew Rate section). The inrush current (I
,
OUT
)
INRUSH
to the load is limited to a level proportional to the load
capacitance (C ) and the slew rate:
L
● If no sense resistor is present, bilevel fault protection
is disabled and load-probing circuitry is enabled (see
the Load Probing section).
C × SR
1000
L
I
=
INRUSH
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).
where SR is the slew rate in V/ms and C is load capacitance
L
in μF.
For operation with and without R
, once V
-
SENSE
GATE
If load probing (see the Load Probing section) is successful,
slew-rate limiting is employed to gradually turn on the
MOSFET.
V
exceeds V
, PGOOD and/or PGOOD assert.
OUT
CB,EN
OUT
When V
- V
= V
, the devices enable
GATE
CB,EN
standard bilevel fault protection with normal I
(see the
CB
Bilevel Fault Protection section).
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Load Probing
Normal Operation
The devices’ load-probing circuitry detects short-circuit
conditions during startup. Load probing is active only
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:
when no external R
is detected. As the device
SENSE
begins load probing, SC_DET is connected to V
CC
through an internal switch with an on-resistance of R
LP
(Figure 6). V
limited at ≈200mA.
then charges the load with a probe current
CC
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.
I
= (V
- V
)/(R + R )
SC
(Figure 1)
(0.2V typ) within
PROBE
CC
OUT
LP
If the load voltage does not reach V
LP,TH
t
LP
, 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).
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
Load probing can only be, and must be, employed when
not using an external R
.
SENSE
V
OUT
SR = dV
dt
SR = dV
dt
C
= SMALL
L
V
LP,TH
(0.2V typ)
V
OUT
PGOOD*
C
L
= LARGE
I
INRUSH
C
= SMALL
L
PGOOD**
I
PROBE
t
I
LOAD
I
LOAD
< t
V
GATE
PROBE LP
V
THPGOOD
Figure 5. Startup Waveform
3.0V TO 6.7V
14
12
10
8
V
OUT
I
LIM
I
LOAD
tCBS
6
V
= V
S
CC
*MAX5924B, MAX5924D, MAX5925B, MAX5925D, AND MAX5926 ONLY.
**MAX5924A, MAX5924C, MAX5925A, MAX5925C, AND MAX5926 ONLY.
4
2
4
6
8
10
12
14
V
CC
(V)
Figure 6. Load-Probe Resistance vs. Supply Voltage
Figure 7. Slow Comparator Response to an Overcurrent Fault
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
or autoretry modes. Figure 7 shows the slow comparator
response to an overcurrent fault.
Table 1. Selecting Fault Management
Mode (MAX5926)
Bilevel Fault Protection
LATCH
Low
FAULT MANAGEMENT
Autoretry mode
Latched mode
Bilevel Fault Protection in Startup Mode
High
Bilevel fault protection is disabled in startup mode, and is
enabled when V
exceeds V
at the end
GATE-VOUT
CB,EN
of the startup period.
Slow Comparator
The slow comparator is disabled during startup while the
external MOSFET turns on.
When no R
is detected, neither slow nor fast
SENSE
comparator is active during startup because the high
of the MOSFET when not fully enhanced would
R
D(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
signal an artificially-high V
probing prior to startup insures that the output is not short-
circuited.
voltage. Load
IN-VSENSE
capacitance with I
. The magnitude of I
GATE,PD
GATE,PD
depends on the external MOSFET gate-to-source voltage
When R
is detected, the slow comparator is
SENSE
(V ). The discharge current is strongest immediately
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.
GS
following a fault and decreases as the MOSFET gate is
discharged (Figure 8a).
60
V
CC
= 13.2V
50
40
30
20
10
0
3
4
0
1
2
5
6
7
V
GS
(V)
Figure 8a. Gate Discharge Current vs. MOSFET Gate-to-Source
Voltage
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
PGOOD/PGOOD asserts only if the part is in normal
Fast Comparator
mode and no faults are present.
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 I
comparator is disabled during startup when no R
is detected
Undervoltage Lockout (UVLO)
UVLO circuitry prevents the devices from turning on the
external MOSFET until V
exceeds the UVLO thresh-
CC
(Figure 8a). The fast
GATE,PD
old, V , for t . UVLO protects the external
UVLO D,UVLO
SENSE
MOSFET from insufficient gate-drive voltage, and t
D,UVLO
ensures that the board is fully plugged into the backplane
and V is stable prior to powering the hot-swapped
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).
CC
system. Any input voltage transient at V
below the
CC
UVLO threshold for more than the UVLO deglitch period
(t ) resets the device and initiates a startup sequence.
DG
Device operation is protected from momentary input-
voltage steps extending below the UVLO threshold for a
deglitch period, t . However, the power-good output(s)
DG
In autoretry, a fault turns the external MOSFET off then
automatically restarts the device after the autoretry delay,
may momentarily deassert if the magnitude of a negative
step in V
exceeds approximately 0.5V, and V
drops
CC
CC
t . During the autoretry delay, pull EN or EN1 low to
RETRY
below V . Operation is unaffected and the power-good
UVLO
restart the device. In latched mode, pull EN or EN1 low for
at least 100μs to clear a latched fault and restart the device.
output(s) assert(s) within 200μs, as shown in Figure 8b. This
figure also shows that if the UVLO condition exceeds t
=
DG
900μs (typ), the power-good output(s) again deassert(s)
and the load is disconnected.
Power-Good Outputs
The power-good output(s) are open-drain output(s) that
deassert:
Determining Inrush Current
● When V
● During t
● When V
< V
UVLO
CC
D,UVLO
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:
< V
GS
THPGOOD
● During load probing
● When disabled (EN = GND (MAX5924/MAX5925),
EN1 = GND or EN2 = high (MAX5926))
● During fault management
dV
OUT
● During t
or when latched off (MAX5924A,
RETRY
I
(A) = C
= C ×SR
L
INRUSH
L
dt ×1000
MAX5924B, MAX5925A, MAX5925B, or MAX5926
(LATCH = low)).
V
S
= V = 13.2V
CC
C
= 1µF
SLEW
C = 10µF
L
GATE
2V/div
MOSFET ONLY
V
CC
5V/div
1V/div
1V/div
MOSFET AND
= 20nF
C
GATE
0V
0V
PGOOD
200µs/div
10ms/div
Figure 8b. PGOOD Behavior with Large Negative Input-Voltage
Step when VS is Near V
Figure 9. Impact of C
on the V
Waveform
GATE
GATE
S(MIN)
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
where C is the load capacitance in μF and SR is the
SLEW sets the maximum slew rate to the minimum value.
L
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.
Calculate C
using the following equation:
SLEW
-9
C
= 330 10 / SR
SLEW
where, SR is the desired slew rate in V/ms and C
is in nF.
SLEW
This equation is valid for C
≥ 100nF. For higher SR,
SLEW
see the Typical Operating Characteristics.
A 2μA (typ) pullup current clamped to 1.4V causes an
initial jump in the gate voltage, V , if C is small
and the slew rate is slow (Figure 3). Figure 9 illustrates
how the addition of gate capacitance minimizes this initial
Slew Rate
GATE
GATE
The MAX5924/MAX5925/MAX5926 limit the slew rate of
V
OUT
. Connect an external capacitor, C
, between
SLEW
SLEW and GND to adjust the slew-rate limit. Floating
jump. C
should not exceed 25nF.
GATE
EN (MAX5924/MAX5925), EN1/EN2 (MAX5926)
V
S
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
R
CB
R
1
V
GATE
SENSE
CB
CC
EN1, V , and GND sets the programmable turn-on voltage
S
EN (EN1)
OUT
to a voltage greater than V
(Figure 10).
UVLO
MAX5924_
MAX5925_
MAX5926
R
2
Selecting a Circuit-Breaker Threshold
R
SC
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.
SC_DET
(EN2)
GND
As load current flows through R
(Figure 12) or
DS(ON)
R
V
(Figure 13), a voltage drop is generated. After
SENSE
GS
(R + R ) V
EN/UVLO
2
1
( ) ARE FOR MAX5926 ONLY.
V
=
S,TURN-ON
exceeds V , the MAX5924/MAX5925/MAX5926
CB,EN
R
2
monitor this voltage to detect overcurrent conditions. If
this voltage exceeds the circuit-breaker threshold, the
Figure 10. Adjustable Turn-On Voltage
15,000
15,000
TC = 0ppm/°C
TC = 3300ppm/°C
V
V
V
= 1.5V
= 1.4V
= 1.3V
S
S
S
12,000
12,000
9000
6000
3000
0
V
= 1.5V
S
9000
6000
3000
0
V
S
V
S
V
S
V
S
V
S
= 1.4V
= 1.3V
= 1.2V
= 1.1V
= 1.0V
V
S
V
S
V
S
= 1.2V
= 1.1V
= 1.0V
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 11. Maximum Circuit-Breaker Programming Resistor vs. Temperature
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
external MOSFET turns off and the power-good output(s)
deassert(s). To accommodate different MOSFETs, sense
resistors, and load currents, the MAX5924/MAX5925/
To determine the proper circuit-breaker resistor value use
the following equation, which refers to Figure 12:
I
(
xR
(T) + V
DS(ON)
CB,OS
)
TRIPSLOW
MAX5926 voltage across R
can be set between 10mV
CB
R
CB
=
and 500mV. The value of the circuit-breaker voltage must
be carefully selected based on V (Figure 11).
I
CB
S
where I
current.
is the desired slow-comparator trip
TRIPSLOW
No R
Mode
SENSE
When operating without R
, calculate the circuit-
SENSE
The fast-comparator trip current is determined by the
breaker threshold using the MOSFET’s R
at the
DS(ON)
selected R value and cannot be adjusted independently.
CB
worst possible operating condition, and add a 20% overcurrent
margin to the maximum circuit current. For example, if a
The fast-comparator trip current is given by:
I
x R
+R
± V
CB
CB,OS
(
)
MOSFET has an R
normalized on-resistance factor of 1.75 at T = +105°C,
of 0.06Ω at T = +25°C, and a
CB
CBF
DS(ON)
A
I
=
TRIPFAST
A
R
(T)
DS(ON)
the R
used for calculation is the product of these
DS(ON)
SC_DET must be connected to OUT through the selected
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.
R
when not using R
.
SC
SENSE
R
Mode
SENSE
When operating with R
, calculate the circuit-breaker
SENSE
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-
I
I
LOAD
LOAD
R
R
SENSE
DS(ON)
V
V
OUT
S
V
V
OUT
S
R
CB
R
CB
GATE
OUT
SLOW
CB
SENSE
V
CB GATE
SENSE OUT
CB,TH
COMPARATOR
SLOW
COMPARATOR
V
CB,TH
MAX5925
MAX5926
R
CBF
V
CB,OS
MAX5925
MAX5926
V
CB,OS
R
CBF
FAST
COMPARATOR
FAST
COMPARATOR
I
I
CB
CB
TC
SELECT
TC
SELECT
V
CB,OS
V
CB,OS
V
V
CBF,TH
CBF,TH
Figure 12. Circuit Breaker Using R
Figure 13. Circuit Breaker Using R
SENSE
DS(ON)
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
breaker threshold is then a product of this current and
= 0.06Ω, or (0.06Ω) x (2.4A) = 0.144V. Using
Table 2. Programming the Temperature
Coefficient (MAX5926)
R
SENSE
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.
TC
High
Low
TC
(ppm/°C)
ICB
0
3300
To determine the proper circuit-breaker resistor value, use
the following equation, which refers to Figure 13:
Table 3. Suggested External MOSFETs
APPLICATION
CURRENT (A)
PART
DESCRIPTION
I
xR
I
+ V
OS
CB,
(
)
TRIPSLOW
SENSE
R
=
CB
International Rectifier
CB
1
SO-8
IRF7401
where, I
current.
is the desired slow-comparator trip
TRIPSLOW
2
5
Siliconix Si4378DY
SO-8
Siliconix SUD40N02-06
Siliconix SUB85N02-03
DPAK
D2PAK
The fast-comparator trip current is determined by the
selected R value and cannot be adjusted independently.
10
CB
The fast-comparator trip current is given by:
50
45
40
35
30
25
20
I
x R
+R
± V
CB,OS
(
)
CB
CB
CBF
R
V
R
= V = 13.2V, R = 672Ω, I
= 5A,
TRIPSLOW
S
CC
CB
I
=
TRIPFAST
(25) = 6.5mΩ
DS(ON)
SENSE
CIRCUIT-BREAKER TRIP REGION
SC_DET should be connected to V
when using
(V
V
)
SENSE CB
CC
R
.
SENSE
Circuit-Breaker Temperature Coefficient
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 R
coefficient. Use the MAX5926’s TC input to select the
V
= R
(T) x I
DS(ON) LOAD(MAX)
SENSE
(4500ppm/°C)
= I (T) x R + V
CB,OS
V
CB CB
CB
temperature
(3300ppm/°C)
DS(ON)
-40
-15
10
35
60
85
110
circuit-breaker programming current’s temperature coefficient,
TEMPERATURE (°C)
TC
(see Table 2). The MAX5924 temperature coefficient
ICB
is preset to 0ppm/°C, and the MAX5925’s is preset to
3300ppm/°C.
Figure 14. Circuit-Breaker Trip Point and Current-Sense
Voltage vs. Temperature
Setting TC
to 3300ppm/°C allows the circuit-breaker
ICB
threshold to track and compensate for the increase in
the MOSFET’s R 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.
where V
is the worst-case offset voltage. Figure 14
CB,OS
DS(ON)
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.
R
and I
are temperature dependent, and can
DS(ON)
CB
therefore be expressed as functions of temperature. At a
given temperature, the MAX5925/MAX5926 indicate an
overcurrent condition when:
I
x R
(T) ≥ I (T) x R
+ |V
|
TRIPSLOW
DS(ON)
CB
CB
CB,OS
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Table 4. Component Manufacturers
COMPONENT
MANUFACTURER
Dale-Vishay
IRC
PHONE
WEBSITE
402-564-3131
828-264-8861
888-522-5372
310-233-3331
www.vishay.com
www.irctt.com
Sense Resistors
Fairchild
www.fairchildsemi.com
www.irf.com
MOSFETs
International Rectifier
Select the external nMOSFET according to the
application’s current and voltage level. Table 3 lists some
recommended components. Choose the MOSFET’s on-
charge to a voltage above V until the external MOSFET’s
IN
body diode conducts to clamp the capacitor voltage at V
IN
plus the body-diode V . When testing or operating with no
F
resistance, R
, low enough to have a minimum
load, it is therefore recommended that the output capacitor
be paralleled with a resistor of value:
DS(ON)
voltage drop at full load to limit the MOSFET power
dissipation. High R can cause undesired power
DS(ON)
R = V /120μA
X
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.
where V is the maximum acceptable output voltage prior
X
to hot-swap completion.
Design Procedure
Given:
Using the devices in latched mode allows the consideration
● V
= V = 5V
S
CC
of MOSFETs with higher R
and lower power ratings.
DS(ON)
● C = 150μF
L
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.
● Full-Load Current = 5A
● No R
SENSE
● I
= 500mA
INRUSH
Procedures:
1) Calculate the required slew rate and corresponding C
Be sure to select a MOSFET with an appropriate gate drive
:
SLEW
(see the Typical Operating Characteristics). Typically, for
I
V
INRUSH
V
CC
less than 3V, select a 2.5V V
MOSFET.
SR =
= 3.3
GS
1000× C
ms
L
Optional Sense Resistor
Select the sense resistor in conjunction with R
−9
−9
to
CB
330×10
330×10
C
=
=
= 0 . 1µ F
SLEW
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
V
ms
SR
3.3
2) Select a MOSFET and determine the worst-case
power dissipation.
configuration. If latched mode is selected, P
2
=
RSENSE
(I
)
x R
; if autoretry is selected, then
OVERLOAD
SENSE
3) Minimize power dissipation at full load current and
at high temperature by selecting a MOSFET with an
2
P
= (I
)
x R
x (t /t
).
RSENSE
OVERLOAD
SENSE
ON RETRY
Choose a sense-resistor power rating of twice the
appropriate R
. Assume a 20°C temperature
DS(ON)
P
for long-term reliable operation. In addition,
2
RSENSE
difference between the devices and the MOSFET.
ensure that the sense resistor has an adequate I T rating
to survive instantaneous short-circuit conditions.
For example, at room temperature the IRF7822’s
= 6.5mΩ. The temperature coefficient for this
device is 4000ppm/°C. The maximum R
R
DS(ON)
No-Load Operation
The internal circuitry is capable of sourcing a current at the
for the
DS(ON)
MOSFET at T
= +105°C is:
J(MOSFET)
OUT terminal of up to 120μA from a voltage V + V
.
IN
GS
ppm
If there is no load on the circuit, the output capacitor will
R
= 6.5mΩ × 1+ (105°C − 25°C)× 4000
DS(ON)105
°C
= 8.58mΩ
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
The power dissipation in the MOSFET at full load is:
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.
2
2
P
= I R = (5A) × 8.58mΩ = 215mW
D
4) Select R
.
CB
Since the MOSFET’s temperature coefficient
is 4000ppm/°C, which is greater than TC
(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).
ICB
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.
I
= I
+ 20% = 5A + 20% = 6A
TRIPSLOW
R
FULL LOAD
= 8.58mΩ (max), from step 2
DS(ON)105
I
= 58μA x (1 + (3300ppm/°C x (85 - 25)°C)
= 69.5μA (min)
CB85
I
xR
+ V
(
TRIPSLOW
)
DS(ON)105
CB,OS
R
=
CB
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.
I
CB85
R
= ((6A x 8.58mΩ) + 4.7mV)/69.5μA = 808Ω
CB
HIGH-CURRENT PATH
SENSE RESISTOR
R
CB
MAX5924
MAX5925
MAX5926
Figure 15. Kelvin Connection for the Current-Sense Resistor
Maxim Integrated
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Selector Guide
POWER-GOOD OUTPUT
CIRCUIT-BREAKER
PART
TEMPCO
(ppm/°C)
FAULT MANAGEMENT
PGOOD
PGOOD
(OPEN-DRAIN)
(OPEN-DRAIN)
MAX5924A
0
Latched
Latched
—
ü
ü
—
ü
MAX5924B
MAX5924C
MAX5924D
MAX5925A
MAX5925B
MAX5925C
MAX5925D
MAX5926
0
0
Autoretry
—
ü
0
Autoretry
—
ü
3300
Latched
—
ü
3300
3300
Latched
—
ü
Autoretry
—
ü
3300
Autoretry
—
ü
0 or 3300 (Selectable)
Latched or Autoretry (Selectable)
ü
Ordering Information
Chip Information
TRANSISTOR COUNT: 3751
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
PROCESS: BiCMOS
MAX5924AEUB
MAX5924BEUB
MAX5924CEUB*
MAX5924DEUB*
MAX5925AEUB
MAX5925BEUB*
MAX5925CEUB*
MAX5925DEUB*
MAX5926EEE
10 µMAX
10 µMAX
Package Information
10 µMAX
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.
10 µMAX
10 µMAX
10 µMAX
10 µMAX
16 QSOP–EP**
PACKAGE TYPE
10 µMAX
PACKAGE CODE DOCUMENT NO.
*Future product—contact factory for availability.
**EP = Exposed pad.
U10CN+1
21-0061
21-0112
10 QSOP-EP
E16E-1
Maxim Integrated
│ 21
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MAX5924/MAX5925/
MAX5926
1V to 13.2V, n-Channel Hot-Swap Controllers
Require No Sense Resistor
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
DESCRIPTION
CHANGED
0
8/05
Initial release
—
Revised data sheet title, General Description, Features, EC table, Typical
Operating Circuit, and added No-Load Operation section.
1
6/06
1–13, 15–18
2
3
10/06
4/10
Initial release of MAX5924BEUB and revised EC table.
1–4, 10–12
2–4
Revised EC table.
Updated Circuit-Breaker Programming Current, Circuit-Breaker Trip Gate
Pulldown Current, External Gate Drive and EN, EN1 Reference Threshold
specifications of the Electrical Characteristics table.
4
1/16
2–3
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.
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 specifications 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.
2016 Maxim Integrated Products, Inc.
│ 22
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