19-3320; Rev 1; 1/05
-48V Hot-Swap Controller with V
IN
Step Immunity,
No R
SENSE
, and Overvoltage Protection
MAX5938
General Description
The MAX5938 is a hot-swap controller for -10V to -80V
rails. The MAX5938 allows circuit line cards to be safely
hot-plugged into a live backplane without causing a
glitch on the power supply. It integrates an adjustable
circuit-breaker function requiring no R
SENSE
.
The MAX5938 provides a controlled turn-on for circuit
cards, which limits inrush current and prevents both
glitches on the power-supply rail and damage to board
connectors and components. Before startup, the
MAX5938 performs a Load Probe™ test to detect the
presence of a short-circuit condition. If a short-circuit
condition does not exist, the device limits the inrush cur-
rent drawn by the load by gradually turning on the exter-
nal MOSFET. Once the external MOSFET is fully
enhanced, the MAX5938 provides overcurrent and short-
circuit protection by monitoring the voltage drop across
the R
DS(ON)
of the external power MOSFET. The
MAX5938 integrates a 400mA fast GATE pulldown to
guarantee that the external MOSFET is rapidly turned off
in the event of an overcurrent or short-circuit condition.
The MAX5938 also protects the system against input
voltage (V
IN
) steps. During an input voltage step, the
device limits the current drawn by the load to a safe level
without shutting down the load. The device also includes
ON/OFF control, selectable PGOOD output polarity,
undervoltage (UV) and overvoltage (OV) protection.
The device offers latched (MAX5938L) or autoretry
(MAX5938A) fault management. Both the MAX5938A
and MAX5938L are available in a 16-pin QSOP package
and are specified for the extended (-40°C to +85°C)
temperature range.
♦
-10V to -80V Operation
♦
No External R
SENSE
Required
♦
Drives Large Power MOSFETS
♦
Eliminates Inrush Current Spikes During Hot Plug
into Powered Backplane
♦
Eliminates Inrush Current Spikes and Dropping of
Load During Large V
IN
Steps
♦
Adjustable Circuit-Breaker Threshold with
Temperature Compensation
♦
Circuit-Breaker Fault with Transient Rejection
♦
Shorted Load Detection (Load Probe) Before
Power MOSFET Turn-On
♦
Programmable Load-Voltage Slew Rate Controls
Inrush Current
♦
±2.4% Accuracy, Programmable Turn-On/Off
Voltage (UVLO)
♦
Overvoltage Fault Protection with Transient
Rejection
♦
Autoretry and Latched Fault Management
Available
♦
Low Quiescent Current (1mA)
Features
Ordering Information
PART
MAX5938AEEE
MAX5938LEEE
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 QSOP
Applications
Servers
Telecom Line Cards
Network Switches
Solid-State Circuit Breakers
Network Routers
Pin Configuration
TOP VIEW
GND 1
N.C. 2
OFF 3
ON 4
OV 5
STEP_MON 6
16 PGOOD
15 N.C.
14 V
OUT
MAX5938
13 N.C.
12 CB_ADJ
11 GATE
10 N.C.
9
LP
Typical Operating Circuit appears at end of data sheet.
Load Probe is a trademark of Maxim Integrated Products, Inc.
POL_SEL 7
V
EE
8
QSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
-48V Hot-Swap Controller with V
IN
Step Immunity,
No R
SENSE
, and Overvoltage Protection
MAX5938
ABSOLUTE MAXIMUM RATINGS
V
EE
, V
OUT
, PGOOD, LP,
STEP_MON to GND............................................+0.3V to -85V
PGOOD to V
OUT
.....................................................-0.3V to +85V
V
OUT
, LP, STEP_MON to V
EE
.................................-0.3V to +85V
GATE to V
EE
...........................................................-0.3V to +20V
ON, OFF, OV, POL_SEL, CB_ADJ to V
EE
................-0.3V to +6V
Input Current
LP (internally duty-cycle limited)..........................................1A
PGOOD (continuous) ......................................................80mA
GATE (during 15V clamp, continuous) ...........................30mA
GATE (during 2V clamp, continuous) .............................50mA
GATE (during gate pulldown, continuous)......................50mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
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
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
EE
= -10V to -80V, V
IN
= (GND - V
EE
), V
STEP_MON
= V
EE
, R
LP
= 200Ω,
V
ON
= V
OFF
= 2V, V
OV
= V
CB_ADJ
= V
EE
, POL_SEL open, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
EE
= -48V, T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Operating Voltage Range
Operating Supply Current
ON/OFF, OV
ON Reference Threshold Rising
ON Reference Threshold Falling
ON Glitch Rejection (Note 3)
OFF Reference Threshold
ON/OFF/OV Input Bias Current
OV Reference Threshold, Rising
OV Reference Threshold, Falling
OV Transient Rejection
Power-Up Delay (Note 4)
V
OUT
to V
EE
Leakage Current
LP to V
EE
Leakage Current
POL_SEL to V
EE
Input Current
GATE DRIVE
External Gate-Drive Voltage
V
GS
V
GATE
- V
EE
MOSFET fully
enhanced
GATE to V
EE
Clamp Voltage
Power-off,
V
EE
= GND
I
G,ON
R
G,OFF
SR
V
GATE
- V
EE
=
500mV
V
IN
= 10V
14V < V
IN
< 80V
I
CLAMP
= 9mA
I
CLAMP
= 20mA
I
CLAMP
= 1mA
I
CLAMP
= 10mA
-66
V
IN
> 10V
V
IN
> 14V
2.4
6.5
8.1
13.5
6.8
10
16
17
2.1
2.5
-52
9.0
7.5
9.0
19.5
2.55
2.93
-35
14.1
12.5
14.8
µA
mA
V/ms
V
7.2
12.8
V
V
ON_REF,R
V
ON_REF,F
t
REJ
V
OFF_REF
I
BIAS
V
OV_REF,R
V
OV_REF,F
t
OVREJ
t
ONDLY
V
OFF
= V
EE
= -80V, V
OUT
= GND,
PGOOD open
V
OFF
= V
EE
= -80V, LP = GND
POL_SEL = V
EE
-50
V
OV
increasing
V
OV
decreasing
OV increasing
V
ON
increasing
V
ON
decreasing
V
ON
decreasing
1.219
1.069
0.80
1.219
-25
1.219
1.069
0.80
80
1.25
1.125
1.5
220
0.01
0.01
-34
1.25
1.125
1.5
1.25
1.281
1.181
2.25
1.281
+25
1.281
1.181
2.25
380
1
1
-20
V
V
ms
V
nA
V
V
ms
ms
µA
µA
µA
SYMBOL
V
EE
I
CC
CONDITIONS
Referenced to GND
MIN
-80
0.95
TYP
MAX
-10
1.4
UNITS
V
mA
Open-Loop Gate Charge Current
GATE Pulldown Switch
On-Resistance
Output-Voltage Slew Rate
V
GATE
= V
EE
, V
OUT
= GND
l dV
OUT
/dt l, C
SLEW
= 0
2
_______________________________________________________________________________________
-48V Hot-Swap Controller with V
IN
Step Immunity,
No R
SENSE
, and Overvoltage Protection
ELECTRICAL CHARACTERISTICS (continued)
(V
EE
= -10V to -80V, V
IN
= (GND - V
EE
), V
STEP_MON
= V
EE
, R
LP
= 200Ω, V
ON
= V
OFF
= 2V, V
OV
= V
CB_ADJ
= V
EE
, POL_SEL open, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
EE
= -48V, T
A
= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
T
A
= +85°C
CB_ADJ Bias Current
I
CB_ADJ
CB_ADJ = V
EE
T
A
= +25°C
T
A
= -40°C
T
A
= +85°C
CB_ADJ = V
EE
Circuit-Breaker Threshold
V
CB
R
CB_ADJ
= 2kΩ
T
A
= +25°C
T
A
= -40°C
T
A
= +85°C
T
A
= +25°C
T
A
= -10°C
T
A
= -40°C
I
CB_ADJ
Temperature Coefficient
Circuit-Breaker Glitch Rejection
t
CB_DLY
T
A
= +85°C
CB_ADJ = V
EE
Short-Circuit Threshold (Note 5)
V
SC
R
CB_ADJ
= 2kΩ
T
A
= +25°C
T
A
= -10°C
T
A
= -40°C
T
A
= +85°C
T
A
= +25°C
T
A
= -10°C
T
A
= -40°C
Short-Circuit Response Time
INPUT-VOLTAGE STEP PROTECTION
Input-Voltage-Step Detection
Threshold
Input-Voltage-Step Threshold
Offset Current
LOAD-PROBE CIRCUIT
Load-Probe Switch On-Resistance
Load-Probe Timeout
Load-Probe Retry Time
Shorted Load Detection Voltage
Threshold
t
LP
t
LP_OFF
V
TH_LP
Referenced to GND
-220
V
LP
- V
EE
= 1V
80
7.5
220
16 x
t
LP
-200
-180
11
380
Ω
ms
s
mV
STEP
TH
I
STEP_OS
1.219
-10.8
1.25
-10
1.281
-9.2
V
µA
150mV overdrive, C
LOAD
= 0,
to GATE below 1V
224
159
108
-40°C < T
A
< +85°C
1.0
112
75
50
123
85
66
59
41
MIN
55
39
TYP
72
50
33
72
50
33
144
100
82
66
6000
1.2
144
100
82
66
288
200
164
132
330
500
ns
352
241
220
1.6
176
125
114
mV
ppm/°C
ms
165
115
98
mV
85
59
MAX
89
61
µA
UNITS
CIRCUIT BREAKER AND SHORT CIRCUIT
MAX5938
_______________________________________________________________________________________
3
-48V Hot-Swap Controller with V
IN
Step Immunity,
No R
SENSE
, and Overvoltage Protection
MAX5938
ELECTRICAL CHARACTERISTICS (continued)
(V
EE
= -10V to -80V, V
IN
= (GND - V
EE
), V
STEP_MON
= V
EE
, R
LP
= 200Ω, V
ON
= V
OFF
= 2V, V
OV
= V
CB_ADJ
= V
EE
, POL_SEL open, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
EE
= -48V, T
A
= +25°C.) (Notes 1, 2)
PARAMETER
LOGIC AND FAULT MANAGEMENT
Autoretry Delay
t
RETRY
|V
OUT
- V
EE
| falling
PGOOD Assertion Threshold
Hysteresis
PGOOD Assertion Delay Time
(Note 6)
PGOOD Low Voltage
PGOOD Open-Drain Leakage
t
PGOOD
V
OL
I
L
I
SINK
= 1mA, referenced to V
OUT,
V
OUT
< (GND - 5V )
V
EE
= -80V, PGOOD = GND
0.70
16 x
t
LP
0.74
x V
CB
0.26
x V
CB
1.26
0.05
0.01
1.85
0.4
1
ms
V
µA
s
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
mV
Note 1:
All currents into pins are positive and all currents out of pins are negative. All voltages referenced to V
EE
, unless otherwise
specified.
Note 2:
All limits are 100% tested at +25°C and +85°C. Limits at -40°C and -10°C are guaranteed by characterization.
Note 3:
V
ON
drops below the V
ON_REF,F
threshold are ignored during this time.
Note 4:
Delay time from a valid on condition until the load-probe test begins.
Note 5:
The short-circuit threshold is V
SC
= 2 x V
CB
.
Note 6:
The time when PGOOD condition is met until PGOOD signal is asserted.
Typical Operating Characteristics
(V
EE
= -48V, GND = 0V, V
IN
= GND - V
EE
, POL_SEL = floating, all voltages are referenced to V
EE
, unless otherwise noted. T
A
= +25°C,
unless otherwise noted.)
SUPPLY CURRENT
vs. INPUT VOLTAGE
MAZ5938 toc01
SUPPLY CURRENT
vs. TEMPERATURE
V
IN
= 72V
V
IN
= 48V
0.8
0.6
0.4
0.2
6.5
0
6.0
-40
-15
10
35
60
85
10
20
V
IN
= 12V
MAX5938 toc02
GATE-DRIVE VOLTAGE
vs. INPUT VOLTAGE
10.0
GATE DRIVER VOLTAGE (V)
9.5
9.0
8.5
8.0
7.5
7.0
MAX5938 toc03
2.0
1.8
1.6
SUPPLY CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
10
20
30
40
50
60
70
1.2
1.0
SUPPLY CURRENT (mA)
10.5
80
30
40
50
60
70
80
INPUT VOLTAGE (V)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
-48V Hot-Swap Controller with V
IN
Step Immunity,
No R
SENSE
, and Overvoltage Protection
Typical Operating Characteristics (continued)
(V
EE
= -48V, GND = 0V, V
IN
= GND - V
EE
, POL_SEL = floating, all voltages are referenced to V
EE
, unless otherwise noted. T
A
= +25°C,
unless otherwise noted.)
GATE PULLDOWN CURRENT
vs. GATE VOLTAGE
MAX5938 toc04
MAX5938
RETRY TIME
vs. TEMPERATURE
3.9
3.8
RETRY TIME (s)
3.7
3.6
3.5
3.4
3.3
3.2
3.1
3.0
C
GATE
= 0, C
LOAD
= 100µF
MAX5938 toc05
500
450
GATE PULLDOWN CURRENT (mA)
400
350
300
250
200
150
100
50
0
0
1
2
3
4
5
6
7
8
9
4.0
10
-40
-15
10
35
60
85
V
GATE
(V)
TEMPERATURE (°C)
STARTUP WAVEFORM
MAX5938 toc06
CIRCUIT-BREAKER EVENT
MAX5938 toc07
SHORT-CIRCUIT EVENT
MAX5938 toc08
V
IN
50V/div
V
GATE
10V/div
V
OUT
50V/div
V
PGOOD
50V/div
R
LOAD
= 48Ω
C
LOAD
= 100µF
40ms/div
V
IN
= 48V
IRFR1310
R
CB_ADJ
= 2kΩ
POL_SEL = OPEN
V
IN
= 48V
V
GATE
10V/div
V
GATE
10V/div
V
OUT
50V/div
V
PGOOD
50V/div
I
IN
2A/div
1ms/div
400ns/div
V
OUT
50V/div
V
PGOOD
50V/div
IRFR1310
R
CB_ADJ
= 2kΩ
R
LOAD
= 48Ω
POL_SEL = OPEN
I
IN
2A/div
I
IN
10A/div
NORMALIZED CIRCUIT-BREAKER
THRESHOLD vs. TEMPERATURE
NORMALIZED CIRCUIT-BREAKER THRESHOLD (%)
MAX5938 toc09
V
OUT
SLEW RATE
vs. TEMPERATURE
9.5
9.0
SLEW RATE (V/ms)
8.5
8.0
7.5
7.0
6.5
6.0
5.5
V
IN
= 12V
V
IN
= 48V
C
GATE
= 0, C
LOAD
= 100µF
V
IN
= 72V
MAX5938 toc10
1.6
1.4
1.2
1.0
0.8
0.6
0.4
-40
-15
10
35
60
10.0
5.0
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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