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General Description

The MAX5921/MAX5939 hot-swap controllers allow a cir-
cuit card to be safely hot plugged into a live backplane.
The MAX5921/MAX5939 operate from -20V to -80V and
are well suited for -48V power systems. These devices
are pin compatible with both the LT1640 and LT4250 and
provide improved features over these devices.

The MAX5921/MAX5939 provide a controlled turn-on to
circuit cards preventing damage to board connectors,
board components, and preventing glitches on the
power-supply rail. The MAX5921/MAX5939 provide
undervoltage, overvoltage, and overcurrent protection.
These devices ensure that the input voltage is stable
and within tolerance before applying power to the load.

Both the MAX5921 and MAX5939 protect a system
against overcurrent and short-circuit conditions by turn-
ing off the external MOSFET in the event of a fault con-
dition. The MAX5921/MAX5939 protect against input
voltage steps by limiting the load current to a safe level
without turning off power to the load.

The device features an open-drain power-good status
output, PWRGD or PWRGD for enabling downstream
converters (see Selector Guide). A built-in thermal shut-
down feature is also included to protect the external
MOSFET in case of overheating. The MAX5939 features
a latched fault output. The MAX5921 contains built-in
autoretry circuitry after a fault condition.

The MAX5921/MAX5939 are available in an 8-pin SO
package and operate in the extended -40°C to +85°C
temperature range.

Applications

Telecom Line Cards

Network Switches/Routers

Central-Office Line Cards

Server Line Cards

Base-Station Line Cards

Features

o Allows Safe Board Insertion and Removal

from a Live -48V Backplane

o Pin-Compatible with LT1640 and LT4250
o Circuit Breaker Immunity to Input Voltage Steps

and Current Spikes

o 450mA GATE Pulldown Current During Short-

Circuit Condition

o Exponential GATE Pulldown Current
o Withstands -100V Input Transients with No

External Components

o Programmable Inrush and Short-Circuit Current

Limits

o Operates from -20V to -80V
o Programmable Overvoltage Protection
o Programmable Undervoltage Lockout

with Built-In Glitch Filter

o Overcurrent Fault Integrator
o Powers Up into a Shorted Load
o Power-Good Control Output
o Thermal Shutdown Protects External MOSFET

MAX5921/MAX5939

-48V Hot-Swap Controllers with External

SENSE

and High Gate Pulldown Current

________________________________________________________________ Maxim Integrated Products

GATE

SENSE

DRAIN

PWRGD

(PWRGD)

TOP VIEW

MAX5921
MAX5939

() FOR MAX5921B/F AND MAX5939B/F.

Pin Configuration

Ordering Information

19-2946; Rev 0; 9/03

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.

PART

TEMP RANGE

PIN-PACKAGE

MAX5921AESA

-40°C to +85°C

8 SO

MAX5921BESA

-40°C to +85°C

8 SO

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

Ordering Information continued at end of data sheet.

MAX5921/MAX5939

-48V Hot-Swap Controllers with External
R

SENSE

and High Gate Pulldown Current

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= 0V, V

= 48V, T

= -40°C to +85°C, unless otherwise noted. Typical values are at T

= +25°C, unless otherwise noted.) (Notes 1, 4)

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 Are Referenced to VEE, Unless Otherwise Noted
Supply Voltage (VDD - VEE )................................-0.3V to +100V
DRAIN, PWRGD, PWRGD ....................................-0.3V to +100V
PWRGD to DRAIN ................................................ -0.3V to +95V
PWRGD to VDD .......................................................-95V to +85V
SENSE (Internally Clamped) .................................-0.3V to +1.0V
GATE (Internally Clamped) ....................................-0.3V to +18V
UV and OV..............................................................-0.3V to +60V
Current into SENSE...........................................................+40mA

Current into GATE...........................................................+300mA
Current into Any Other Pin................................................+20mA
Continuous Power Dissipation (TA = +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

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

POWER SUPPLIES

Operating Input Voltage Range

Supply Current

Current into V

with UV = 3V, OV, DRAIN,

SENSE = V

, GATE = floating

0.7

GATE DRIVER AND CLAMPING CIRCUITS

Gate Pullup Current

GATE drive on, V

GATE

= V

-30

-45

-60

µA

Gate Pulldown Current

SENSE

- V

= 100mV, V

GATE

= 2V (Note 2)

External Gate Drive

GATE

- V

, steady state, 20V

80V

13.5

GATE to V

Clamp Voltage

GSCLMP

GATE

- V

, I

= 30mA

16.4

CIRCUIT BREAKER

Current-Limit Trip Voltage

= V

SENSE

- V

SENSE Input Current

SENSE

= 50mV

-1

-0.2

µA

UNDERVOLTAGE LOCKOUT

Supply Internal Undervoltage
Lockout Voltage High

UVLOH

increasing

13.8

15.4

17.0

Supply Internal Undervoltage
Lockout Voltage Low

UVLOL

decreasing

11.8

13.4

15.0

UV INPUT

UV High Threshold

UVH

UV voltage increasing

1.240

1.255

1.270

UV Low Threshold

UVL

UV voltage decreasing

1.105

1.125

1.145

UV Hysteresis

UVHY

130

UV Input Current

INUV

UV = V

-0.5

µA

OV INPUT

OV High Threshold

OVH

OV voltage rising

1.235

1.255

1.275

OV Low Threshold

OVL

OV voltage decreasing

1.189

1.205

1.221

OV Voltage Reference Hysteresis

OVHY

OV Input Current

INOV

OV = V

-0.5

µA

MAX5921/MAX5939

-48V Hot-Swap Controllers with External

SENSE

and High Gate Pulldown Current

_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

= 0V, V

= 48V, T

= -40°C to +85°C, unless otherwise noted. Typical values are at T

= +25°C, unless otherwise noted.) (Notes 1, 4)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

PWRGD OUTPUT SIGNAL (REFERENCED TO DRAIN)

DRAIN Input Current

DRAIN

= 48V

250

µA

DRAIN Threshold for PWRGD

DRAIN

- V

threshold for power-good

condition, DRAIN decreasing

1.1

1.7

2.0

GATE High Threshold

GATE

- V

GATE

, decreasing

1.0

1.6

2.0

PWRGD

= 80V, V

DRAIN

= 48V

PWRGD,

PWRGD Output

Leakage

PWRGD

= 80V, V

DRAIN

= 0V

µA

PWRGD Low Voltage
(V

PWRGD

- V

)

DRAIN

- V

< V

, I

SINK

= 5mA

(A, E versions)

0.11

0.4

PWRGD Low Voltage
(V

PWRGD

- V

DRAIN

)

DRAIN

= 5V, I

SINK

= 5mA (B, F versions)

0.11

0.4

OVERTEMPERATURE PROTECTION

Overtemperature Threshold

OT(TH)

Junction temperature, temperature rising

135

°C

Overtemperature Hysteresis

HYS

See Thermal Shutdown section

°C

AC PARAMETERS

OV High to GATE Low

PHLOV

Figures 1a, 2

0.5

µs

UV Low to GATE Low

PHLUV

Figures 1a, 3

0.4

µs

OV Low to GATE High

PLHOV

Figures 1a, 2

3.3

µs

UV High to GATE High

PLHUV

Figures 1a, 3

8.4

SENSE High to GATE Low

PHLSENSE

Figures 1a, 4a

µs

A, B versions

0.35

0.5

0.65

Current Limit to GATE Low

PHLCL

Time from continuous
current limit to GATE
shutdown (see Overcurrent
Fault Integrator section),
Figures 1b, 4b

E, F versions

1.4

2.0

2.6

Figures 1a, 5a; A and E versions

8.2

DRAIN Low to

PWRGD Low

DRAIN Low to (PWRGD - DRAIN)
High

PHLDL

Figures 1a, 5a; B and F versions

8.2

Figures 1a, 5b; A and E versions

8.2

GATE High to

PWRGD Low

GATE High to (PWRGD - DRAIN)
High

PHLGH

Figures 1a, 5b; B and F versions

8.2

TURN-OFF

Latch-Off Period

OFF

(Note 3)

A, B, E, F versions

128 x

PHLCL

Note 1:

All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to V

unless otherwise specified.

Note 2:

Gate pulldown current after the current limit to GATE low (t

PHLCL

) time has elapsed.

Note 3:

Minimum duration of GATE pulldown following a circuit breaker fault. The MAX5921_ automatically restarts after a circuit
breaker fault. The MAX5939_ is latched off and can be reset by toggling UV low. The GATE pulldown does not release until
t

OFF

has elapsed.

Note 4:

The min/max limits are 100% production tested at +25°C and +85°C and guaranteed by design at -40°C.

MAX5921/MAX5939

-48V Hot-Swap Controllers with External
R

SENSE

and High Gate Pulldown Current

_______________________________________________________________________________________

Typical Operating Characteristics

= +48V, V

= 0V, T

= +25°C, unless otherwise noted.)

43.0

43.2

43.8

43.6

43.4

44.8

44.6

44.2

44.0

44.4

45.0

-40

-15

GATE PULLUP CURRENT

vs. TEMPERATURE

MAX5921TOC04

TEMPERATURE (

°C)

GATE PULLUP CURRENT (

GATE

= 0V

-40

-15

GATE PULLDOWN CURRENT

vs. TEMPERATURE AFTER A FAULT

MAX5921TOC05

TEMPERATURE (

°C)

GATE PULLDOWN CURRENT (mA)

GATE

= 2V

100

GATE PULLDOWN CURRENT

vs. OVERDRIVE DURING A CURRENT FAULT

MAX5921TOC06

OVERDRIVE (mV)

GATE PULLDOWN CURRENT (mA)

GATE

= 2V

100

400

300

200

500

600

900

750

1050

1200

GATE PULLDOWN CURRENT

vs. OVERDRIVE DURING A SHORT CIRCUIT

MAX5921TOC07

OVERDRIVE (mV)

GATE PULLDOWN CURRENT (mV)

GATE

= 2V

160

120

140

100

180

-40

-15

PWRGD OUTPUT LOW VOLTAGE

vs. TEMPERATURE (MAX5921A)

MAX5921TOC08

TEMPERATURE (

°C)

PWRGD OUTPUT LOW VOLTAGE (mV)

OUT

= 5mA

0.001

0.01

0.1

100

-40

-15

PWRGD OUTPUT LEAKAGE CURRENT

vs. TEMPERATURE (MAX5921B)

MAX5921TOC09

TEMPERATURE (

°C)

PWRGD OUTPUT LEAKAGE CURRENT (nA)

DRAIN

- V

> 2.4V

200

100

500

400

300

800

700

600

900

100

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX5921TOC01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (

= +85

°C

= +25

°C

= -40

°C

100

GATE VOLTAGE

vs. SUPPLY VOLTAGE

MAX5921TOC02

SUPPLY VOLTAGE (V)

GATE VOLTAGE (V)

= +25

°C

-40

-15

CURRENT-LIMIT TRIP VOLTAGE

vs. TEMPERATURE

MAX5921TOC03

TEMPERATURE (

°C)

TRIP VOLTAGE (mV)

Part Number MAX5939