Rainbow Electronics MAX5937 User Manual

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

________________________________________________________________ Maxim Integrated Products 1

19-3281; Rev 0; 6/04

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.

General Description

The MAX5936/MAX5937 are hot-swap controllers for

-10V to -80V rails. The MAX5936/MAX5937 allow circuit
line cards to be safely hot-plugged into a live back­plane without causing a glitch on the power supply.
These devices integrate a circuit-breaker function
requiring no R

SENSE

.

The MAX5936/MAX5937 provide a controlled turn-on
for circuit cards, limiting inrush, preventing glitches on
the power-supply rail, and preventing damage to board
connectors and components. Before startup, the
devices perform 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
current drawn by the load by gradually turning on the
external MOSFET. Once the external MOSFET is fully
enhanced, the MAX5936/MAX5937 provides overcur­rent and short-circuit protection by monitoring the volt­age drop across the R

DS(ON)

of the external power
MOSFET. The MAX5936/MAX5937 integrate a 400mA
fast GATE pulldown to guarantee that the power
MOSFET is rapidly turned off in the event of an overcur­rent or short-circuit condition.

The MAX5936/MAX5937 protect the system against
input voltage (VIN) steps by providing VINstep immuni­ty. The MAX5936/MAX5937 provide an accurate UVLO
voltage. The MAX5936 has an open-drain, active-low
PGOOD output and the MAX5937 has an open-drain,
active-high PGOOD output.

The MAX5936/MAX5937 are offered with 100mV,
200mV, and 400mV circuit-breaker thresholds, in addi­tion to a non-circuit-breaker option. These devices are
offered in latched and autoretry fault management, are
available in 8-pin SO packages, and specified for the
extended (-40°C to +85°C) temperature range (see the
Selector Guide).

Applications

Servers
Telecom Line Cards
Network Switches
Solid-State Circuit Breaker
Network Routers

Features

♦ -10V to -80V Operation
♦ No R

SENSE

Required

♦ Drives Large Power MOSFETS
♦ Programmable Inrush Current Limit During Hot

Plug

♦ 100mV, 200mV, 400mV, and No-Circuit-Breaker

Threshold Options

♦ Circuit-Breaker Fault with Transient Rejection
♦ Shorted Load Detection (Load Probe) Before

Power MOSFET Turn-On

♦ ±2.4% Accurate Undervoltage Lockout (UVLO)
♦ Autoretry and Latched Fault Management

Available

♦ Low Quiescent Current

GATE

LPV

EE

1
2

8
7

PGOOD
(PGOOD)

V

OUT

UVLO

STEP_MON

GND

SO

TOP VIEW

3

4

6

5

MAX5936
MAX5937

( ) FOR THE MAX5937.

Pin Configuration

Load Probe is a trademark of Maxim Integrated Products, Inc.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX5936_ _ESA

-40°C to +85°C 8 SO

MAX5937_ _ESA

-40°C to +85°C 8 SO

Note: The first “_” represents A for the autoretry and L for the
latched fault management option.
The second “_” represents the circuit-breaker threshold.
See the Selector Guide for additional information.

Selector Guide and Typical Operating Circuit appear at end
of data sheet.

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VEE, V

OUT

, PGOOD (PGOOD), LP,

STEP_MON to GND............................................+0.3V to -85V

PGOOD (PGOOD) to V

OUT

....................................-0.3V to +85V

PGOOD (PGOOD), LP, STEP_MON to V

EE

............-0.3V to +85V

GATE to V

EE

...........................................................-0.3V to +20V

UVLO to V

EE

.............................................................-0.3V to +6V

Input Current

LP (internally, duty-cycle limited).........................................1A

PGOOD (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)

8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW

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

ELECTRICAL CHARACTERISTICS

(VEE= -10V to -80V, VIN= GND - VEE, V

STEP_MON =VEE

, RLP= 200Ω, UVLO open, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at V

EE

= -48V, TA= +25°C.) (Notes 1, 2)

PARAMETER SYMBOL CONDITIONS

UNITS

Operating Voltage Range V

EE

Referenced to GND

V

Operating Supply Current I

CC

mA

V

UVLO,R

lVEEl increasing

V

UVLO,F

lVEEl decreasing

V

UVLO Reference Threshold,
V

EE

Rising

V

UVLO

increasing

V

UVLO Reference Threshold,
V

EE

Falling

V

UVLO

decreasing

V

UVLO Input Resistance 20 50 kΩ
UVLO Transient Rejection t

OVREJ

ms

Power-Up Delay (Note 3) t

ONDLY

80

ms

VEE and UVLO Glitch Rejection
(Note 4)

t

REJ

ms

V

OUT

to VEE Leakage Current VEE = -80V, V

OUT

= GND

1µA

LP to VEE Leakage Current VEE = -80V, V

LP

= GND

1µA

VIN = 10V

External Gate-Drive Voltage V

GS

V

GATE

- V

EE

14 ≤ VIN ≤ 80V

10

V

I

CLAMP

= 9mA

16

MOSFET fully
enhanced

I

CLAMP

= 20mA 17

I

CLAMP

= 1mA

GATE to VEE Clamp Voltage

Power-off,
V

EE

= GND

I

CLAMP

= 10mA

V

V

GATE

= VEE, V

OUT

= GND

µA

VIN > 10V 9

GATE Pulldown Switch
On-Resistance

R

GATE

V

GATE

- VEE =

500mV

V

IN

> 14V

Ω

Output-Voltage Slew Rate SR l dV

OUT

/dt l

9

V/ms

Default VEE Undervoltage Lockout

MIN TYP MAX

-80 -10

0.95 1.4

-33.5 -31.0 -29.5

-28

V

UVLO_REF,R

V

UVLO_REF,F

Open-Loop Gate-Charge Current

1.219 1.25 1.281

1.069 1.125 1.181

0.8 1.5 2.25
220 380

0.8 1.5 2.25

0.01

0.01

6.5 6.8 7.2

8.1

13.5

2.1 2.55

2.5 2.9

-66 -52 -35

7.5 12.5

2.4

12.8

19.5

14.1

14.8

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VEE= -10V to -80V, VIN= GND - VEE, V

STEP_MON =VEE

, RLP= 200Ω, UVLO open, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at V

EE

= -48V, TA= +25°C.) (Notes 1, 2)

PARAMETER SYMBOL CONDITIONS

UNITS

Circuit-Breaker Tempco -40°C < TA <+85°C

ppm/°C

Circuit-Breaker Glitch Rejection t

CB_DLY

ms
TA = +85°C
TA = +25°C 85
TA = -10°C 64 79 94

MAX5936LA/
MAX5936AA/
MAX5937LA/
MAX5937AA

T

A

= -40°C 62
TA = +85°C
TA = +25°C
TA = -10°C

MAX5936LB/
MAX5936AB/
MAX5937LB/
MAX5937AB

T

A

= -40°C
TA = +85°C
TA = +25°C
TA = -10°C

Circuit-Breaker Threshold V

CB

MAX5936LC/
MAX5936AC/
MAX5937LC/
MAX5937AC

T

A

= -40°C

mV

TA = +85°C
TA = +25°C
TA = -10°C

MAX5936LA/
MAX5936AA/
MAX5937LA/
MAX5937AA

T

A

= -40°C
TA = +85°C
TA = +25°C
TA = -10°C

MAX5936LB/
MAX5936AB/
MAX5937LB/
MAX5937AB

T

A

= -40°C
TA = +85°C
TA = +25°C
TA = -10°C

Short-Circuit Threshold V

SC

MAX5936LC/
MAX5936AC/
MAX5937LC/
MAX5937AC

T

A

= -40°C

mV

Short-Circuit Response Time
(Note 5)

150mV overdrive, C

LOAD

= 0,

to GATE below 1V

ns

INPUT-VOLTAGE-STEP PROTECTION

Input-Voltage-Step Detection
Threshold

STEP

TH

V

Input-Voltage-Step Threshold
Offset Current

I

STEP_OS

µA

LOAD-PROBE CIRCUIT

VLP - VEE = 1V

11 Ω

Load-Probe Timeout t

LP

80

ms

Load-Probe Retry Time t

LP_OFF

16 x

s

Load-Probe Voltage Threshold

Referenced to GND

mV

Load-Probe Switch On-Resistance

V

THSC-DET

1.219 1.250 1.281

MIN TYP MAX

6000

1.0 1.2 1.6

118 140 162

100 115

244 284 324
180 200 220
135 158 181

485 568 651
355 400 445
270 316 362

220 280 340
160 200 240
111 158 205

470 568 667
350 400 450
255 316 377

962 1136 1310
700 800 900
510 632 754

-10.8 -10.0 -9.2

-220 -200 -180

124

248

124

248

496
330 500

7.5

220 380

t

LP

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

4 _______________________________________________________________________________________

Note 1: All currents into pins are positive and all currents out of pins are negative. All voltages referenced to VEE, 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: Delay time from a valid on-condition until the load probe test begins.
Note 4: V

EE

or UVLO voltages below V

UVLO,F

or V

UVLO_REF,F

, respectively, are ignored during this time.

Note 5: The time (V

OUT

- VEE) > VSC+ overdrive until (V

GATE

- VEE) drops to approximately 90% of its initial high value.

Note 6: The time when the PGOOD (PGOOD) condition is met until the PGOOD (PGOOD) signal is asserted.

ELECTRICAL CHARACTERISTICS (continued)

(VEE= -10V to -80V, VIN= GND - VEE, V

STEP_MON =VEE

, RLP= 200Ω, UVLO open, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at V

EE

= -48V, TA= +25°C.) (Notes 1, 2)

PARAMETER SYMBOL CONDITIONS

UNITS

LOGIC AND FAULT MANAGEMENT

Autoretry Delay t

RETRY

16 x

s

|V

OUT

- VEE| falling

PGOOD (PGOOD) Assertion
Threshold

Hysteresis

mV

PGOOD (PGOOD) Assertion Delay
Time (Note 6)

ms

PGOOD (PGOOD) Low Voltage V

OL

I

SINK

= 1mA, referenced to V

OUT,

V

OUT

< GND - 5V for PGOOD (PGOOD)

V

PGOOD (PGOOD) Open-Drain
Leakage

I

L

VEE = -80V, V

PGOOD(PGOOD)

,

V

PGOOD(PGOOD)

= GND

1µA

MIN TYP MAX

t

LP

0.74 x
V

CB

0.26 x
V

CB

0.67 1.26 1.85

0.05 0.4

0.01

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

_______________________________________________________________________________________ 5

SUPPLY CURRENT

vs. INPUT VOLTAGE

MAZ5936 toc01

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

706040 503020

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0

10 80

SUPPLY CURRENT
vs. TEMPERATURE

MAX5936 toc02

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

603510-15

0.2

0.4

0.6

0.8

1.0

1.2

0

-40 85

VIN = 72V

VIN = 48V

VIN = 12V

GATE-DRIVE VOLTAGE

vs. INPUT VOLTAGE

MAX5936 toc03

INPUT VOLTAGE (V)

GATE-DRIVE VOLTAGE (V)

706040 503020

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

6.0
10 80

GATE PULLDOWN CURRENT

vs. GATE VOLTAGE

MAX5936 toc04

V

GATE

(V)

GATE PULLDOWN CURRENT (mA)

986 72 3 4 51

50

100

150

200

250

300

350

400

450

500

0

010

RETRY TIME

vs. TEMPERATURE

MAX5936 toc05

TEMPERATURE (°C)

RETRY TIME (s)

603510-15

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

3.0

-40 85

C

GATE

= 0, C

LOAD

= 100µF

STARTUP WAVEFORM

MAX5936 toc06

40ms/div

V

IN

50V/div
V

GATE

10V/div

V

OUT

50V/div

I

IN

2A/div

V

PGOOD

50V/div

MAX5936_A CIRCUIT-BREAKER EVENT

MAX5936 toc07

1ms/div

V

GATE

10V/div

V

OUT

50V/div

I

IN

2A/div

V

PGOOD

50V/div

Typical Operating Characteristics

(VEE= -48V, GND = 0V, VIN= GND - VEE, all voltages are referenced to VEE, TA= +25°C, unless otherwise noted.)

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

6 _______________________________________________________________________________________

MAX5936_A SHORT-CIRCUIT EVENT

MAX5936 toc08

400ns/div

V

GATE

10V/div

V

OUT

50V/div

I

IN

10A/div

V

PGOOD

50V/div

NORMALIZED CIRCUIT-BREAKER

THRESHOLD vs. TEMPERATURE

MAX5936 toc09

TEMPERATURE (°C)

NORMALIZED CIRCUIT-BREAKER THRESHOLD (%)

603510-15

0.6

0.8

1.0

1.2

1.4

1.6

0.4

-40 85

V

OUT

SLEW RATE

vs. TEMPERATURE

MAX5936 toc10

TEMPERATURE (°C)

SLEW RATE (V/ms)

603510-15

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

5.0

-40 85

C

GATE

= 0, C

LOAD

= 100µF

VIN = 48V

VIN = 72V

VIN = 12V

MAX5936_A INPUT VOLTAGE

STEP EVENT (NO FAULT)

MAX5936 toc11

4ms/div

V

GATE

10V/div
V

OUT

50V/div

I

IN

1A/div

V

PGOOD

50V/div

V

IN

50V/div

R

LOAD

= 75Ω

MAX5936_A INPUT VOLTAGE

STEP EVENT (FAULT)

MAX5936 toc12

4ms/div

V

GATE

10V/div
V

OUT

50V/div

I

IN

2A/div

V

PGOOD

50V/div

V

IN

50V/div

R

LOAD

= 75Ω

GATE TO VEE CLAMP VOLTAGE

AT POWER OFF

MAX5936 toc13

I

SINK

(mA)

GATE CLAMPING VOLTAGE (V)

18161412108642

0.5

1.0

1.5

2.0

2.5

3.0

0

020

VEE = GND = 0V

GATE TO VEE CLAMP VOLTAGE

MOSFET FULLY ENHANCED

MAX5936 toc14

I

SINK

(mA)

GATE CLAMPING VOLTAGE (V)

181612 144 6 8 102

9

10

11

12

13

14

15

16

17

18

8

020

VEE = -48V, V

UVLO

= 2V

Typical Operating Characteristics (continued)

(VEE= -48V, GND = 0V, VIN= GND - VEE, all voltages are referenced to VEE, TA= +25°C, unless otherwise noted.)

MAX5936/MAX5937

-48V Hot-Swap Controllers with V

IN

Step Immunity and No R

SENSE

_______________________________________________________________________________________ 7

Detailed Description

The MAX5936/MAX5937 hot-swap controllers incorpo­rate overcurrent fault management and are intended for
negative-supply-rail applications. The MAX5936/
MAX5937 eliminate the need for an external R

SENSE

and include VINinput-step protection and load probe,
which prevents powering up into a shorted load. They
are intended for negative 48V telecom power systems
where low cost, flexibility, multifault management, and
compact size are required. The MAX5936/MAX5937 are
ideal for the widest range of systems from those
requiring low current with small MOSFETs to high­current systems requiring large power MOSFETs and
low on-resistance.

The MAX5936/MAX5937 control an external n-channel
power MOSFET placed in the negative supply path of
an external load. When no power is applied, the GATE
output of the MAX5936/MAX5937 clamps the VGSof the
MOSFET to 2V, keeping the MOSFET turned off. When
power is applied to the MAX5936/MAX5937, the 2V

clamp at the GATE output is replaced by a strong pull­down device pulling GATE to VEEand the VGSof the
MOSFET to 0V. As shown in Figure 2, this transition
enables the MAX5936/MAX5937 to keep the power
MOSFET continually off during the board insertion
phase when the circuit board first makes contact with
the backplane. Without this clamp, the GATE output of
a powered-down controller would be floating and the
MOSFET reverse transfer capacitance (gate-to-drain)
would pull up and turn on the MOSFET gate when the
MOSFET drain is rapidly pulled up by the VINstep dur­ing backplane contact. The MAX5936/MAX5937 GATE
clamp can overcome the gate-to-drain capacitance of
large power MOSFETs with added slew-rate control
(C

SLEW

) capacitors while eliminating the need for addi­tional gate-to-source capacitance. The MAX5936/
MAX5937 will keep the MOSFET off indefinitely if the
supply voltage is below the user-set UVLO threshold or
if a short circuit is detected in the load connected to the
drain of the power MOSFET.

PIN

MAX5936

NAME FUNCTION

11GND Ground. The high-supply connection for a negative-rail hot-swap controller.

22UVLO

Undervoltage Lockout Input, On/Off Control. Referenced to VEE. Drive UVLO above the

1.25V rising threshold to turn on the device. To turn off the device, drive UVLO below the

1.125V falling threshold for the 1.5ms glitch rejection period. Leave UVLO disconnected for
the default 31V undervoltage lockout threshold. Cycle UVLO to unlatch the MAX5936L/
MAX5937L after a fault.

33

Input Voltage Step Monitor. 1.25V voltage threshold referenced to VEE. Connect a resistor
between STEP_MON and V

EE

to set the step sensitivity. Connect a capacitor from GND to
STEP_MON to adjust the step response relative to a step increase at VEE to eliminate false
circuit-breaker and short-circuit faults. Connect to VEE to disable the step immunity function
(see the Selecting Resistor and Capacitor Values for Step Monitor section in the
Applications Information).

44V

EE

Negative Input Voltage

55LP

Load-Probe Detect. Connect a resistor from LP to V

OUT

to set the load-probe test current.

Limit load-probe test current to 1A. Connect to V

EE

to disable the load-probe function.

66GATE Gate-Drive Output. Connect to the gate of the external n-channel MOSFET.

77V

OUT

Output Voltage Sense. V

OUT

is the negative rail of the load. Connect to the drain of the

external n-channel MOSFET.

8—PGOOD

Power-Good, Active-Low, Open-Drain Output. Referenced to V

OUT

. PGOOD asserts low

when V

OUT

is within the limits and there is no fault.

—8PGOOD

Power-Good, Active-High, Open-Drain Output. Referenced to V

OUT

. PGOOD asserts high

when V

OUT

is within limits and there is no fault.

Pin Description

MAX5937

STEP_MON