19-1832; Rev 0a; 1/01
-48V Simple Swapper Hot-Swap Switches
General Description
The MAX5911/MAX5912 are fully integrated hot-swap
switches for negative supply rails. These devices allow
the safe insertion and removal of circuit cards into live
backplanes or ports without causing problematic glitch-
es on the negative power-supply rail. They also monitor
various circuit parameters and disconnect the load if a
fault condition occurs, alerting the host with a logic-level
FAULT
output. The MAX5911/MAX5912 operate over a
voltage range of -16V to -65V and are designed to permit
hot plugging of an IP phone into a hub, but are not limit-
ed to that operation.
During startup, an internal power FET regulates the cur-
rent between the backplane power source and the load
to 280mA for MAX5911 and 415mA for MAX5912. After
startup, the FET is fully enhanced to reduce its on-resis-
tance. To ensure robust operation, the MAX5911/
MAX5912 contain built-in safety features that prevent
damage to the internal FET. They include an enable
input, which responds to positive logic signals (+3.3V or
+5V), allowing the host system to disconnect the load.
ENABLE is also used to reset the device after a latching
fault condition occurs.
The MAX5911/MAX5912 Simple Swapper™ hot-swap
ICs monitor four parameters for these fault conditions:
undervoltage lockout (UVLO), power-not-good, zero-
current detection, and thermal shutdown. These
devices are available in the extended temperature
range, -40°C to +85°C. The MAX5911 and MAX5912
come in 8-pin and 16-pin SOIC packages, respectively.
Features
o
Provides Safe Hot Swap for -16V to -65V Power
Supplies
o
280mA Current Limit for MAX5911
o
415mA Current Limit for MAX5912
o
Zero-Current Load Disconnect
o
Integrated Power FET
o
Status Output Reports Fault Condition
o
Internal Switch-Protection Circuitry
o
Built-In Thermal Shutdown
o
DGND Can Vary Up to ±5V with Respect to AGND
MAX5911/MAX5912
Ordering Information
PART
MAX5911ESA
MAX5912ESE
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 SO
16 SO
Simple Swapper is a trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
GATE
1
V
IN
2
8
7
UVLO
V
OUT
AGND
ENABLE
Applications
IP Phones
Network Routers
Network Switches
Internet Appliances
Power-Over-LAN
FAULT
3
MAX5911
6
5
DGND
4
8 SO
Typical Operating Circuit
V
IN
(-48V)
+3.3V
0.1µF
V
IN
MAX5911
MAX5912
UVLO
FAULT
POSITIVE
LOGIC
LOAD
V
OUT
N.C.*
N.C.*
GATE
V
IN
V
IN
FAULT
DGND
1
2
3
4
5
6
7
8
16
N.C.*
15
UVLO
14
V
OUT
13
V
IN
MAX5912
12
V
IN
11
AGND
10
ENABLE
9
N.C.*
3.3kΩ
ENABLE
DGND
AGND
N.C.*
16 SO
AGND
DGND
*THESE PINS ARE NOT INTERNALLY CONNECTED.
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
-48V Simple Swapper Hot-Swap Switches
MAX5911/MAX5912
ABSOLUTE MAXIMUM RATINGS
Voltages are with respect to AGND, unless otherwise noted.
V
IN
..........................................................................+0.3V to -70V
V
OUT
............................................................+0.3V to (V
IN
- 0.3V)
ENABLE to DGND ..................................................-0.3V to +11V
ENABLE to V
IN
.......................................................-0.3V to +70V
FAULT
to DGND .....................................................-0.3V to +11V
UVLO to V
IN
............................................................-0.3V to +11V
DGND ..........................................................................-5V to +5V
DGND to V
IN
...........................................................-0.3V to +70V
FAULT
Sink Current ............................................................10mA
Continuous Output Current ...............................Internally Limited
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SO (derate 5.9mW/°C above +70°C)..................470mW
16-Pin SO (derate 12.9mW/°C above +70°C)...........1039mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°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 SPECIFICATIONS
(V
IN
= -48V, AGND = DGND = 0, UVLO = open circuit, V
ENABLE
= +3.3V, and T
A
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
Input Voltage Range
Supply Current
Maximum V
OUT
Current
DMOS On-Resistance
V
OUT
Leakage Current
ENABLE Low Voltage
ENABLE High Voltage
ENABLE High Input Current
ENABLE Low Pulse Width
(Note 1)
FAULT
Output Low Voltage
FAULT
Output Leakage Current
Zero-Current Detection
Threshold
Zero-Current Detection
Threshold Hysteresis
Zero-Current Detection Delay
(Note 2)
Current-Limit Delay (Note 3)
Power-Good Threshold
Power-Good Hysteresis
V
IL
V
IH
I
IH
t
EPW
V
OL
I
OH
IF
TH
IF
HY
IF
DEL
t
LIMIT
V
PG
PG
HYS
V
OUT
shorted to AGND
|V
IN
- V
OUT
|, |V
IN
- V
OUT
| decreasing
% of V
PG
1.95
280
I
FAULT
= 3mA
V
FAULT
= +3.3V
Decreasing load current
-12
-8
1.5
350
10
2.15
5
520
20
2.35
SYMBOL
V
IN
I
IN
I
OUT(MAX)
R
DS(ON)
Measured at AGND at the end of output
voltage slew
V
OUT
= V
IN
+ 5V
MAX5911 I
OUT
= -225mA,
MAX5912 I
OUT
= -350mA
Measured on V
OUT
when internal DMOS is
shut off
Referenced to DGND
Referenced to DGND
V
ENABLE
= +3.3V
200
0.4
10
-4
2.0
140
300
MAX5911
MAX5912
-310
-457
CONDITIONS
MIN
-65
1.5
-280
-415
2.5
TYP
MAX
-16
2.5
-250
-373
4
10
0.8
UNITS
V
mA
mA
Ω
µA
V
V
µA
ns
V
µA
mA
mA
ms
µs
V
%
2
_______________________________________________________________________________________
-48V Simple Swapper Hot-Swap Switches
ELECTRICAL SPECIFICATIONS (continued)
(V
IN
= -48V, AGND = DGND = 0, UVLO = open circuit, V
ENABLE
= +3.3V, and T
A
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
Power-Not-Good Output Delay
(Note 4)
Thermal Shutdown Temperature
(Note 5)
Default UVLO
UVLO Hysteresis
UVLO Comparator Threshold
UVLO Input Resistance
R
UVLO
SYMBOL
PG
DEL
T
J
UVLO open circuit, |V
IN
| increasing
UVLO open circuit, percentage of UVLO
threshold
Referenced to V
IN
, UVLO open circuit,
|V
IN
| increasing
-30
CONDITIONS
After |V
IN
- V
OUT
| increases above
(V
PG
+ PG
HYS
)
MIN
8
TYP
14
140
-28
12
+1.258
95
-26
MAX
20
UNITS
ms
o
MAX5911/MAX5912
C
V
%
V
kΩ
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Minimum ENABLE low pulse width required to unlatch fault condition.
The delay from I
OUT
falling below the zero-current threshold until
FAULT
is latched low and V
OUT
is disabled.
The time from an output overcurrent or short-circuit condition until the output goes into current limit.
The time from V
OUT
falling until
FAULT
is asserted low.
FAULT
is not latched for Power-Not-Good condition.
When the device goes into thermal shutdown, the output is disabled and
FAULT
is latched low.
Typical Operating Characteristics
(V
IN
= -48V, AGND = DGND = 0, UVLO = open circuit, V
ENABLE
= +3.3V, R
LOAD
= 1.8kΩ, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5911 toc01
SUPPLY CURRENT
vs. AMBIENT TEMPERATURE
MAX5911 toc02
ON-RESISTANCE
vs. AMBIENT TEMPERATURE
I
LOAD
= 150mA
2.8
ON-RESISTANCE (Ω)
2.6
2.4
2.2
2.0
1.8
1.6
MAX5911 toc03
1.8
NO LOAD
1.6
SUPPLY CURRENT (mA)
1.540
NO LOAD
1.535
SUPPLY CURRENT (mA)
1.530
1.525
1.520
1.515
1.510
3.0
1.4
1.2
1.0
0.8
-65
-55
-45
-35
-25
-15
SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
-48V Simple Swapper Hot-Swap Switches
MAX5911/MAX5912
Typical Operating Characteristics (continued)
(V
IN
= -48V, AGND = DGND = 0, UVLO = open circuit, V
ENABLE
= +3.3V, R
LOAD
= 1.8kΩ, T
A
= +25°C, unless otherwise noted.)
MAX5911 TURN-ON WAVEFORMS
(R
L
= 1.8kΩ, C
L
= NONE)
A
0
0
B
B
MAX5911 TURN-ON WAVEFORMS
(R
L
= 1.8kΩ, C
L
= 47µF)
A
0
0
MAX5911 toc04
MAX5911 toc05
MAX5911 TURN-OFF WAVEFORMS
(R
L
= 1.8kΩ, C
L
= NONE)
A
0
0
B
MAX5911 toc06
C
0
t = 10µs/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
C: FAULT, 2V/div
C
0
C
0
t = 2ms/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
C: FAULT, 2V/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
t = 10µs/div
C: FAULT, 2V/div
MAX5911 TURN-OFF WAVEFORMS
(R
L
= 1.8kΩ, C
L
= 47µF)
A
0
0
B
MAX5911
OVERCURRENT RESPONSE
MAX5911 toc08
MAX5911 toc07
MAX5911
ZERO-CURRENT RESPONSE
A
0
0
B
MAX5911 toc09
A
0
0
B
0
C
0
t = 50ms/div
C: FAULT, 2V/div
A: FAULT, 5V/div
B: V
OUT
, 50V/div
C: I
OUT
, 200mA/div
C
C
0
t = 100ms/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
t = 50ms/div
A: FAULT, 5V/div
C: I
OUT
, 50mA/div
B: V
OUT
, 50V/div
MAX5912 TURN-ON WAVEFORMS
(R
L
= 1.8kΩ, C
L
= NONE)
A
0
0
B
MAX5911 toc10
MAX5912 TURN-ON WAVEFORMS
(R
L
= 1.8kΩ, C
L
= 47µF)
A
0
0
B
MAX5911 toc11
MAX5912 TURN-OFF WAVEFORMS
(R
L
= 1.8kΩ, C
L
= NONE)
A
0
0
B
MAX5911 toc12
C
0
C
0
t = 10µs/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
C: FAULT, 2V/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
C
0
t = 1ms/div
C: FAULT, 2V/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
t = 10µs/div
C: FAULT, 2V/div
4
_______________________________________________________________________________________
-48V Simple Swapper Hot-Swap Switches
Typical Operating Characteristics (continued)
(V
IN
= -48V, AGND = DGND = 0, UVLO = open circuit, V
ENABLE
= +3.3V, R
LOAD
= 1.8kΩ, T
A
= +25°C, unless otherwise noted.)
MAX5912 TURN-OFF WAVEFORMS
(R
L
= 1.8kΩ, C
L
= 47µF)
A
0
0
B
B
MAX5911/MAX5912
MAX5911 toc13
MAX5912
OVERCURRENT RESPONSE
A
0
0
MAX5912
ZERO-CURRENT RESPONSE
A
0
0
B
MAX5911 toc14
MAX5911 toc15
0
C
0
t = 100ms/div
A: ENABLE, 5V/div
B: V
OUT
, 20V/div
C: FAULT, 2V/div
A: FAULT, 5V/div
B: V
OUT
, 20V/div
t = 40ms/div
C: I
OUT
, 200mA/div
C
C
0
t = 40ms/div
A: FAULT, 5V/div
B: V
OUT
, 20V/div
C: I
OUT
, 100mA/div
Pin Description
PIN
MAX5911
1
MAX5912
3
GATE
Gate of the Internal Power MOSFET. Normally leave open circuit. To slow
down the output voltage ramp, connect two capacitors, one to V
IN
and one to
V
OUT
. See
GATE Connections
for details.
Voltage Input Terminal. Bypass V
IN
, to AGND with a 0.1µF capacitor to
improve noise immunity.
Fault Logic Output, open-drain. Tie
FAULT
to the positive logic supply with a
3.3kΩ resistor. Referenced to DGND.
Digital Ground. Ground reference level for the external positive logic,
FAULT,
and ENABLE. DGND can vary up to
±5V
with respect to AGND to
accommodate differential ground voltages in large systems.
ENABLE Input. Turns on and off the internal FET. ENABLE is a positive logic-
level input referenced to DGND. Drive ENABLE high to enable V
OUT
. Drive
ENABLE low to disable V
OUT
. Pulse ENABLE low to reset the MAX5911/
MAX5912 after a latched fault condition occurs.
Analog Ground. Ground reference level for V
IN
, V
OUT
, and UVLO.
Voltage Output Terminal
Undervoltage Lockout Input. Leave UVLO open circuit for default setting
of -28V. Alternatively, UVLO can be connected to a resistive divider to set the
lockout voltage (see the
Changing the Undervoltage Lockout Setting
section).
The comparator threshold level is +1.258V with respect to V
IN
.
No Connection. No internal connection.
NAME
FUNCTION
2
3
4, 5, 12, 13
6
V
IN
FAULT
4
7
DGND
5
10
ENABLE
6
7
11
14
AGND
V
OUT
8
15
UVLO
—
1, 2, 8, 9, 16
N.C.
_______________________________________________________________________________________
5
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