Rainbow Electronics MAX5958 User Manual

General Description

The MAX5957/MAX5958 triple hot-plug controllers are
designed for PCI Express (PCIe)

®

applications. These
devices provide hot-plug control for 12V, 3.3V, and 3.3V
auxiliary supplies of three PCIe slots. The MAX5957/
MAX5958s’ logic inputs/outputs allow interfacing directly
with the system hot-plug management controller or
through an SMBus™ with an external I/O expander such
as the MAX7313. An integrated debounced attention
switch and present-detect signals simplify system design.

The MAX5957/MAX5958 drive six external n-channel
MOSFETs to control the 12V and 3.3V main outputs. The

3.3V auxiliary outputs are controlled through 0.2Ω n-chan­nel MOSFETs. Internal charge pumps provide the gate
drive for the 12V outputs while the gate drive of the 3.3V
output is driven by the 12V input supply clamped to 5.5V
above the respective 3.3V main supply rail. The 3.3V aux­iliary outputs are completely independent from the main
outputs with their own charge pumps.

At power-up, the MAX5957/MAX5958 keep all the
MOSFETs (internal and external) off until the supplies rise
above their respective undervoltage lockout (UVLO)
thresholds. Upon a turn-on command, the MAX5957/
MAX5958 enhance the external and internal MOSFETs
slowly with a constant gate current to limit the power-sup­ply inrush current.

The MAX5957/MAX5958 actively limit the current to pro­tect all outputs at all times and shut down if an overcur­rent condition occurs. After an overcurrent fault condition,
the MAX5957L/MAX5958L latch off while the MAX5957A/
MAX5958A automatically restart after a restart time delay.
The MAX5957/MAX5958 are offered in latch-off or auto­restart versions (see the

Selector Guide

).

The MAX5957/MAX5958 are available in a 56-pin TQFN
package and operate over the -40°C to +85°C temper­ature range.

Applications

Servers
Desktop Mobile Server Platforms
Workstations
Embedded Devices

Features

o PCIe Compliant

o Hot Swap 12V, 3.3V, and 3.3V Auxiliary for 3

PCIe Slots

o Integrated Power MOSFETs for Auxiliary Supply

Rails

o Controls di/dt and dV/dt

o Active Current Limiting Protects Against

Overcurrent/Short-Circuit Conditions

o Programmable Current-Limit Timeout
o PWRGD Signal Outputs with Programmable

Power-On Reset (POR) (160ms Default)

o Latched FAULT Signal Output After Overcurrent

or Overtemperature Fault

o Attention Switch Inputs/Outputs with 4ms

Debounce

o Present-Detect Inputs

o Force-On Inputs Facilitate Testing/Debug

o Thermal Shutdown

o Allow Control Through SMBus with an I/O

Expander

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

________________________________________________________________

Maxim Integrated Products

1

Selector Guide

Ordering Information

19-0884; Rev 0; 7/07

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

+

Denotes a lead-free package.

Pin Configuration and Typical Application Circuit appear at
end of data sheet.

PCI Express is a registered trademark of PCI-SIG Corp.
SMBus is a trademark of Intel Corp.

PART TEMP RANGE

MAX5957AETN+ -40°C to +85°C 56 Thin QFN T5677-1

MAX5957LETN+ -40°C to +85°C 56 Thin QFN T5677-1

MAX5958AETN+ -40°C to +85°C 56 Thin QFN T5677-1

MAX5958LETN+ -40°C to +85°C 56 Thin QFN T5677-1

PIN­PACKAGE

PKG

CODE

PART LATCH OFF AUTORESTART GUARANTEED AUX CURRENT (mA)

MAX5957AETN+ √ 375
MAX5957LETN+ √ 375
MAX5958AETN+ √ 550
MAX5958LETN+ √ 550

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

12VIN

= V

12S_+

= V

12S_-

= 12V, V

3.3S_+=V3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ =

TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND, T

A

= TJ= -40°C to +85°C, unless otherwise

noted. Typical values are at T

A

= TJ= +25°C.) (Note 1)

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 referenced to GND, unless otherwise noted.)

12VIN......................................................................-0.3V to +14V

12G_ ..........................................................-0.3V to (V

12VIN

+ 6V)

12S_+, 12S_-, 3.3G_ ..............................-0.3V to (V

12VIN

+ 0.3V)

3.3VAUXIN, ON_, FAULT_, PWRGD_.......................-0.3V to +6V

PGND ....................................................................-0.3V to +0.3V

All Other Pins ..................................-0.3V to (V

3.3VAUXIN

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

56-Pin Thin QFN (derate 40mW/°C above +70°C) .....3200mW

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

12V SUPPLY (MAIN)

12V Supply Input-Voltage Range V

12V Undervoltage Lockout V

12V Undervoltage Lockout
Deglitch Time

12V Supply Current I

12VIN CONTROL

12VIN Current-Limit Threshold

- V

(V

12S+

12G_ Gate Charge Current I

12G_ Gate Discharge Current I

12G_ Gate High Voltage

- V

(V

12G_

12G_ Threshold Voltage for
PWRGD_ Assertion

12S_- Input Bias Current 1µA

12S_+ Input Bias Current 10 30 µA

3.3V SUPPLY (MAIN)

3.3V Supply Voltage Range V

Undervoltage Lockout (Note 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

12VIN

V

rising 9.5 10 10.5

12VIN

Hysteresis 0.1

V

falling below V

12IN

12UVLO

to UVLO

assertion

V

= 13.2V 1 2.5 mA

12VIN

V

= GND 4 5 6 µA

12G_

12S-

12UVLO

t

DEG,UVLO

12VIN

V

)

12ILIM

12G, CHG

Normal turn-off, ON_ = GND,
V

= 2V

12G_

12G_, DIS

Output short-circuit condition, strong
gate pulldown to regulation,

12VIN

- V

(V

12S+

V

)

12G, H

V

PGTH12

3.3S_+

I

_ = 1µA 4.8 5.3 5.8 V

12G

Referred to V
(Note 2)

12S-)

≥ 1V, V

12VIN

, I

12G_

12G_

= 5V

= 1µA

3.3SA+ rising 2.50 2.65 2.78 V

Hysteresis 30 mV

10.8 12 13.2 V

30 µs

49 54 59 mV

50 150 250 µA

60 120 200 mA

3.0 4.0 4.8 V

3.0 3.3 3.6 V

V

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V

12VIN

= V

12S_+

= V

12S_-

= 12V, V

3.3S_+=V3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ =

TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND, T

A

= TJ= -40°C to +85°C, unless otherwise

noted. Typical values are at T

A

= TJ= +25°C.) (Note 1)

3.3V CONTROL

3.3V Current-Limit Threshold
(V

3.3S_+

3.3G_ Gate Charge Current I

3.3G_ Gate Discharge Current I

3.3G_ Gate High Voltage

- V

(V

3.3G_

3.3G_ Threshold Voltage for
PWRGD_ Assertion

3.3S_- Input Bias Current 1µA

3.3S_+ Input Bias Current 20 60 µA

3.3V AUXILIARY SUPPLY

3.3VAUXIN Supply Input Voltage
Range

3.3VAUXIN Undervoltage
Lockout

3.3VAUXIN Supply Current V

3.3VAUXIN to 3.3VAUXO
Maximum Dropout

3.3VAUXO_ Current-Limit
Threshold

3.3VAUXO_ Threshold for
PWRGD_ Assertion (V3.3VAUXIN

- V3.3VAUXO)

LOGIC SIGNALS

Input-Logic Threshold (ON_,
FON_, AUXON_, PRES-DET_,
INPUT_)

Input Bias Current (ON_,
AUXON_, INPUT_)

FON_, PRES-DET_ Internal Pullup 25 50 75 kΩ

ON_, AUXON_ High-to-Low
Deglitch Time

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

- V

3.3S_+

3.3S_-

V

)

3.3ILIM

3.3G_,CHG

V

= GND 4 5 6 µA

3.3G_

Normal turn-off, ON_ = GND,
V

_ = 2V

3.3G

3.3G_, DIS

Output short-circuit condition, strong
gate pulldown to regulation,
V

_+ - V

3.3S

V

)

3.3G_H

V

PGTH3.3

V

3.3AUXIN

V

3.3VAUXUVLO

I

= 1µA 4.5 5.5 6.8 V

SOURCE

Referred to V
(Note 2)

V

3.3VAUXIN

Hysteresis 30 mV

3.3VAUXIN

I

3.3VAUXO

I

3.3VAUXO

3.3VAUXO_ shorted
to GND

V

PGTH3.3AUX

(Note 2) 400 mV

3.3S_-

3.3AUXIN

≥ 1V, V

, I

3.3G-

3.3G_

= 5V

= 1µA

rising 2.50 2.65 2.78 V

= 3.6V 2.5 5 mA

= 375mA (MAX5957) 225

= 550mA (MAX5958) 280

MAX5957 376 450 564

MAX5958 560 700 850

17 20 23 mV

50 150 250 µA

90 150 250 mA

3.0 4.0 4.5 V

3.0 3.3 3.6 V

Rising edge 1.0 2.0 V

Hysteresis 25 mV

1µA

4µs

mV

mA

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V

12VIN

= V

12S_+

= V

12S_-

= 12V, V

3.3S_+=V3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ =

TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND, T

A

= TJ= -40°C to +85°C, unless otherwise

noted. Typical values are at T

A

= TJ= +25°C.) (Note 1)

Note 1: All devices are 100% production tested at TA= +25°C. Limits over temperature are guaranteed by design.
Note 2: PWRGD_ asserts a time t

POR_HL

after V

PGTH12,VPGTH3.3,

and V

PGTH3.3AUX

conditions are met.

Note 3: The UVLO for the 3.3V supply is sensed at 3.3S_+.
Note 4: This is the time that ON_ or AUXON_ must stay low when resetting a fault condition.

PRES-DET_ High-to-Low Deglitch
Time

PWRGD_ Power-On Reset
Deglitch Time (Note 2)

PWRGD_ Low-to-High Deglitch
Time

PWRGD_, FAULT_ Output Low
Voltage

PWRGD_, FAULT_ Output High
Leakage Current

FAULT_ Timeout t

FAULT_ Timeout During Startup t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

t

DEG

V

PORADJ

= GND 1 µs

357ms

PORADJ = unconnected 90 160 250

t

POR_HL

t

POR_LH

R

R

R

I

SINK

I

SINK

= 20kΩ 35 55 75

PORADJ

= 100kΩ 145 265 380

PORADJ

= 200kΩ 530

PORADJ

= 2mA 0.1

= 30mA 0.8

PWRGD_, FAULT_ = 5.5V 1 µA

TIM = open 5.5 11 17

R

= 15kΩ 1.4 2.6 3.8

FAULT

SU

TIM

R

= 120kΩ 12 22 32

TIM

R

= 300kΩ 53

TIM

ms

4µs

V

ms

2 x

t

FAULT

ms

Autorestart Delay Time t

RESTART

Fault Reset Minimum Pulse Width t

Thermal Shutdown Threshold t

RESET

SD

(Note 4) 100 µs

TJ rising 150

64 x

t

FAULT

Thermal Shutdown Hysteresis 20

OUT_ Debounce Time t

DBC

OUT_ Voltage High I

OUT_ Voltage Low I

= 2mA

SOURCE

= 2mA 0.4 V

SINK

2.6 4.4 6.2 ms

V

3.3 AU X IN

- 0.3

V

3.3 AU X IN

ms

°C

V

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

_______________________________________________________________________________________

5

Typical Operating Characteristics

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

12V INPUT SUPPLY CURRENT

vs. TEMPERATURE

1.10

1.08

1.06

1.04

1.02

1.00

0.98

0.96

SUPPLY CURRENT (mA)

0.94

0.92

0.90

-40 85

TEMPERATURE (°C)

3.3VAUXO_ OUTPUT VOLTAGE
vs. OUTPUT CURRENT

4.0

3.5

3.0

2.5

2.0

1.5

OUTPUT VOLTAGE (V)

1.0

0.5

0

0 1.0

MAX5957 MAX5958

OUTPUT CURRENT (A)

3.3VAUX INTERNAL SWITCH

MAXIMUM DROPOUT vs. TEMPERATURE

0.20

0.18

0.16

0.14

0.12

0.10

0.08

0.06

DROPOUT VOLTAGE (V)

0.04

0.02

I

= 550mA

LOAD

MAX5958

I

= 375mA

LOAD

MAX5957

0

-40 85

TEMPERATURE (°C)

MAX5957 toc01

3.3VAUXIN SUPPLY CURRENT (mA)

603510-15

5.20

5.15

MAX5957 toc04

5.10

5.05

5.00

4.95

4.90

GATE CHARGE CURRENT (µA)

4.85

4.80

0.80.60.40.2 0.90.70.50.30.1

603510-15

4.75

MAX5957 toc07

12V AND 3.3V CURRENT-LIMIT THRESHOLD (mV)

3.3VAUXIN SUPPLY CURRENT
vs. TEMPERATURE

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

-40 85

TEMPERATURE (°C)

12G_ AND 3.3G_ GATE CHARGE

CURRENT vs. TEMPERATURE

-40 85

TEMPERATURE (°C)

12V AND 3.3V CURRENT-LIMIT THRESHOLD

VOLTAGE vs. TEMPERATURE

60

50

40

30

20

10

0

-40 85

12V CURRENT-LIMIT
THRESHOLD

3.3V CURRENT-LIMIT
THRESHOLD

TEMPERATURE (°C)

12G_

3.3G_

ON_ AND AUXON_ LOW-TO-HIGH THRESHOLD

VOLTAGE vs. TEMPERATURE

1.60

1.55

MAX5957 toc02

1.50

1.45

1.40

1.35

THRESHOLD VOLTAGE (V)

1.30

1.25

1.20

603510-15

-40 85

ON_ THRESHOLD

AUXON_ THRESHOLD

TEMPERATURE (°C)

12G_ AND 3.3G_ GATE DISCHARGE

CURRENT vs. TEMPERATURE

180

175

MAX5957 toc05

170

165

160

GATE DISCHARGE CURRENT (µA)

155

150

603510-15

-40 85

3.3G_

12G_

TEMPERATURE (°C)

AUXILIARY CURRENT LIMIT

vs. TEMPERATURE

1.00

0.90

MAX5957 toc08

0.80

0.70

0.60

0.50

0.40

0.30

AUXILIARY CURRENT (mA)

0.20

0.10

603510-15

0

-40 85

TEMPERATURE (°C)

MAX5958

MAX5957

MAX5957 toc03

603510-15

MAX5957 toc06

603510-15

MAX5957 toc09

603510-15

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

12V UNDERVOLTAGE LOCKOUT

THRESHOLD vs. TEMPERATURE

MAX5957 toc10

TEMPERATURE (°C)

UVLO THRESHOLD (V)

6035-15 10

9.85

9.90

9.95

10.00

10.05

10.10

10.15

10.20

9.80

-40 85

3.3VAUXON UNDERVOLTAGE LOCKOUT
THRESHOLD vs. TEMPERATURE

MAX5957 toc11

TEMPERATURE (°C)

UVLO THRESHOLD (V)

603510-15

2.54

2.58

2.62

2.66

2.70

2.52

2.56

2.60

2.64

2.68

2.50

-40 85

12V TURN-ON/TURN-OFF TIME

MAX5957 toc12

40ms/div

12V OUTPUT
VOLTAGE

12G_

ON_

PWRGD_

10V/div

20V/div

5V/div

5V/div

3.3V TURN-ON/TURN-OFF TIME

MAX5957 toc13

40ms/div

3.3V OUTPUT
5V/div

3.3G_
10V/div

ON_
5V/div

PWRGD_
5V/div

3.3V AUXILIARY TURN-ON/TURN-OFF TIME

MAX5957 toc14

40ms/div

3.3AUXO_OUTPUT
VOLTAGE
2V/div

AUXON_
2V/div

PWRGD_
2V/div

TURN-ON DELAY 3.3V OUTPUT AND

3.3V AUXILIARY OUTPUT

MAX5957 toc15

4ms/div

5V/div

5V/div

5V/div

5V/div

10V/div

3.3VAUXO_
OUTPUT VOLTAGE

3.3 OUTPUT VOLTAGE

3.3 INPUT,

3.3VAUXIN

3.3G_

PWRGD

FAULT CONDITION ON 12V MAIN OUTPUT

(AUTORESTART OPTION)

MAX5957 toc16

12G_
20V/div

0A

0V

0V

0V

FAULT_
5V/div

12V OUTPUT CURRENT
5A/div

100ms/div

12V OUTPUT VOLTAGE
10V/div

t

RESTART

R

LOAD

STEP TO 1.5Ω

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

_______________________________________________________________________________________

7

Typical Operating Characteristics (continued)

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

_______________________________________________________________________________________

7

FAULT CONDITION ON 3.3V MAIN OUTPUT

(AUTORESTART OPTION)

R

STEP TO 0.5Ω

LOAD

0A

0V

0V

t

0V

RESTART

100ms/div

FAULT CONDITION ON 12V OUTPUT

(LATCH OPTION MAX5958)

R

STEP TO 1.5Ω

LOAD

MAX5957 toc19

MAX5957 toc17

3.3V MAIN OUTPUT CURRENT
2A/div

3.3G_
10V/div

3.3V OUTPUT VOLTAGE
5V/div

FAULT_
5V/div

12V OUTPUT CURRENT
5A/div

FAULT CONDITION ON AUXILIARY OUTPUT

(AUTORESTART OPTION)

FAULT CONDITION ON 12V OUTPUT

R

STEP

LOAD

TO 1.5Ω

R

STEP TO 4Ω

LOAD

t

RESTART

100ms/div

t

FAULT

MAX5957 toc18

MAX5957 toc20

3.3VAUXO_ OUTPUT CURRENT
500mA/div

0A

3.3VAUXO_ OUTPUT VOLTAGE
2V/div
0V

FAULT_
2V/div
0V

12V OUTPUT CURRENT
5A/div

100ms/div

FAULT CONDITION ON 3.3V OUTPUT

(LATCHOFF OPTION)

R

STEP TO 0.5Ω

LOAD

40ms/div

MAX5957 toc21

12G_
20V/div

12V OUTPUT VOLTAGE
10V/div

FAULT_
5V/div

3.3V OUTPUT CURRENT
2A/div

3.3G_
10V/div

3.3V OUTPUT VOLTAGE
5V/div

FAULT_
5V/div

4ms/div

FAULT CONDITION ON 3.3V MAIN OUTPUT

R

t

FAULT

STEP TO 0.5Ω

4ms/div

MAX5957 toc22

LOAD

12G_
20V/div

12V OUTPUT VOLTAGE
10V/div

FAULT_
5V/div

3.3V OUTPUT CURRENT
2A/div

3.3G_
10V/div

3.3V OUTPUT VOLTAGE
5V/div

FAULT_
5V/div

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

SHORT CIRCUIT ON 12V MAIN OUTPUT

MAX5957 toc25

12G_
20V/div

FAULT_
5V/div

12V OUTPUT CURRENT
5A/div

2ms/div

12V OUTPUT VOLTAGE
10V/div

SHORT CIRCUIT ON 12V MAIN OUTPUT

MAX5957 toc26

12G_
20V/div

FAULT_
5V/div

12V OUTPUT CURRENT
10A/div

4µs/div

12V OUTPUT VOLTAGE
10V/div

0V

0V

0V

FAULT CONDITION ON AUXILIARY OUTPUT

(LATCHOFF OPTION)

MAX5957 toc23

FAULT_
2V/div

3.3VAUXO_ OUTPUT CURRENT
500mA/div

100ms/div

3.3VAUXO_ OUTPUT VOLTAGE
2V/div

R

LOAD

STEP TO 3.5Ω

MAX5958

FAULT CONDITION ON AUXILIARY OUTPUT

MAX5957 toc24

FAULT_
2V/div

3.3VAUXO_ OUTPUT CURRENT
500mA/div

10ms/div

3.3VAUXO_ OUTPUT VOLTAGE
2V/div

R

LOAD

STEP TO 3Ω

t

FAULT

MAX5958

SHORT CIRCUIT ON 3.3V MAIN OUTPUT

MAX5957 toc27

3.3G_
5V/div

FAULT_
5V/div

3.3V OUTPUT CURRENT
2A/div

2ms/div

3.3V OUTPUT VOLTAGE
5V/div

SHORT CIRCUIT ON 3.3V MAIN OUTPUT

MAX5957 toc28

3.3G_
5V/div

FAULT_
5V/div

3.3V OUTPUT CURRENT
10A/div

2µs/div

3.3V OUTPUT VOLTAGE
5V/div

0V

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

_______________________________________________________________________________________

9

Typical Operating Characteristics (continued)

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

SHORT CIRCUIT ON

3.3AUXO_ AUXILIARY OUTPUT

MAX5957 toc29

FAULT_
5V/div

3.3VAUXO_ OUTPUT CURRENT
500mA/div

2ms/div

3.3VAUXO_ OUTPUT VOLTAGE
2V/div

MAX5958

SHORT CIRCUIT ON 3.3VAUXO_

AUXILIARY OUTPUT

MAX5957 toc30

FAULT_
5V/div

3.3VAUXO_ OUTPUT CURRENT
5A/div

0A

0A

4µs/div

3.3VAUXO_ OUTPUT VOLTAGE
2V/div

MAX5958

POWER-UP INTO FAULT

(AUXILIARY SUPPLY)

MAX5957 toc31

3.3VAUXO_ OUTPUT VOLTAGE
2V/div

FAULT_
5V/div

3.3VAUXO_ OUTPUT CURRENT
500mA/div

4ms/div

AUXON_
5V/div

t

SU

R

LOAD

= 3Ω

MAX5958

POWER-UP INTO FAULT (3.3V MAIN)

MAX5957 toc32

4ms/div

3.3V OUTPUT
CURRENT

FAULT_

3.3G_

3.3V OUTPUT
VOLTAGE

ON_, AUXON_

5A/div

5V/div

5V/div

2V/div

5V/div

POWER-UP INTO FAULT

(12V MAIN OUTPUT)

MAX5957 toc33

12V OUTPUT VOLTAGE
10V/div

FAULT_
5V/div

12V OUTPUT CURRENT
5A/div

4ms/div

ON_, AUXON_
5V/div

t

SU

12G_
10V/div

PRESENT-DETECT (ON/OFF) OPERATION

MAX5957 toc34

40ms/div

12V OUTPUT
VOLTAGE

PWRGD_

3.3VAUXO_
OUTPUT VOLTAGE

PRES-DET_

10V/div

5V/div

5V/div

5V/div

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V

12VIN

= V

12S_+

= 12V, V

3.3S_+

= V

3.3S_-

= V

3.3AUXIN

= V

ON_

= V

AUXON_

= V

FON_

= 3.3V, PWRGD_ = FAULT_ = PORADJ = TIM =

OUTPUT_ = OPEN, INPUT_ = PRES-DET_ = PGND = GND. See the

Typical Application Circuit

.)

PRESENT-DETECT (ON/OFF) OPERATION

MAX5957 toc35

4ms/div

12V OUTPUT
VOLTAGE

PWRGD_

3.3V OUTPUT
VOLTAGE

PRES-DET_

10V/div

5V/div

5V/div

5V/div

FORCED-ON (ON/OFF) OPERATION

MAX5957 toc36

40ms/div

12V OUTPUT
VOLTAGE

PWRGD_

3.3V AUXO_
OUTPUT VOLTAGE

FON_

10V/div

5V/div

5V/div

5V/div

FORCED-ON (ON/OFF) OPERATION

MAX5957 toc37

4ms/div

12V OUTPUT
VOLTAGE

PWRGD_

3.3V OUTPUT
VOLTAGE

FON_

10V/div

5V/div

5V/div

5V/div

DEBOUNCED INPUT/OUTPUT OPERATION

MAX5957 toc38

INPUT_
2V/div

10ms/div

OUTPUT_
2V/div

POWER-ON-RESET TIME

vs. PORADJ RESISTOR

MAX5957 toc39

R

PORADJ

(kΩ)

t

POR_HL

(ms)

900800600 700200 300 400 500100

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

0

0 1000

t

FAULT

TIME DELAY vs. TIM RESISTOR

MAX5957 toc40

R

TIM

(kΩ)

t

FAULT

(ms)

800600200 400

20

40

60

80

100

120

140

160

180

200

0

0 1000

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 11

Pin Description

PIN NAME FUNCTION

1 12SB-

2 12SB+

3 AUXONB Slot B 3.3V Auxiliary Output Enable. A logic-high at AUXONB turns on the slot B auxiliary output.

4 ONB

5 INPUT1 Digital Logic Gate Input 1

6 OUTPUT1 Digital Output One. 4ms debounced digital output of INPUT1.

7 INPUT2 Digital Logic Gate Input 2

8 OUTPUT2 Digital Output 2. 4ms debounced digital output of INPUT2.

9, 27 GND Ground

10 FONC

11 PRES-DETC

12 ONC

13 AUXONC Slot C 3.3V Auxiliary Output Enable. A logic-high at AUXONC turns on the slot C auxiliary output.

14 12SC+

15 12SC-

16 12GC

17 3.3SC+

18 3.3SC-

19 3.3GC

20 FAULTC

21 PWRGDC

Slot B 12V Negative Current-Sense Input. Connect 12SB- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.

Slot B 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor
to 12SB+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot B 12V and 3.3V Main Outputs Enable. A logic-high at ONB turns on the 12V and 3.3V main
outputs of slot B (see Table 2).

Slot C Forced-On Input. FONC has a 50kΩ internal pullup to 3.3VAUXIN. A logic-low on FONC turns
on all slot C outputs as long as the power inputs are within their operating range, regardless of the
status of the other input signals. Leave FONC unconnected for normal operation.

Slot C Present-Detect Input. PRES-DETC accepts inputs from PRSNT-# on a PCIe connector. PRES-
DETC has an internal 50kΩ pullup to 3.3VAUXIN. When PRES-DETC is low, the outputs follow the
command from ONC and AUXONC after a 4ms debounced time. When PRES-DETC goes from low
to high, all outputs of the respective slot shut down with no delay.

Slot C 12V and 3.3V Main Outputs Enable. A logic-high at ONC turns on the 12V and 3.3V main
outputs of slot C (see Table 2).

Slot C 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor
to 12SC+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot C 12V Negative Current-Sense Input. Connect 12SC- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.

Slot C 12V Gate-Drive Output. Connect 12GC to the gate of slot C’s 12V MOSFET. At power-up,
12GC is raised to the internal charge-pump voltage level by a constant current.

Slot C 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to

3.3SC+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot C 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using
the Kelvin-sensing technique to ensure accurate current sensing.

Slot C 3.3V Gate-Drive Output. Connect 3.3GC to the gate of slot C’s 3.3V MOSFET. At power-up,

3.3GC is charged to 5.5V above the 3.3V supply by a constant current derived from V
rise time is determined by the external gate capacitance.

Open-Drain Fault Output Signal. FAULTC latches active low whenever slot C outputs are shut down
due to a fault. A fault is either of:

• An overcurrent condition lasting longer than the overcurrent timeout.

• A device over the temperature condition.
If the fault is detected in the main outputs, FAULTC must be reset by toggling the ONC input. If the
fault is in the auxiliary output, FAULTC must be reset by toggling both ONC and AUXONC. For the
autorestart version, FAULTC is reset when the part initiates the next power-on cycle.

Open-Drain Power-Good Output. PWRGDC goes low 160ms
final value and the power MOSFETs are fully enhanced.

after all outputs of slot C reach their

12VIN

. V

3.3GC‘s

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

12 ______________________________________________________________________________________

Pin Description (continued)

PIN NAME FUNCTION

22 3.3AUXOC Slot C 3.3V Auxiliary Power-Supply Output

3.3V Auxiliary Supply Input. 3.3VAUXIN is the input to a charge pump that drives the internal

23, 48, 49 3.3VAUXIN

24, 46 PGND Power Ground. Connect externally to GND.

25 TIM

26 PORADJ

27 GND Ground

28 12VIN

29 N.C. No Connection. Not internally connected.

30 PRES-DETB

31 FONB

32 PRES-DETA

33 FONA

34 OUTPUT3 Digital Output 3. 4ms debounced digital output of INPUT3.

35 INPUT3 Digital Logic Gate Input 3

36 ONA

37 AUXONA Slot A 3.3V Auxiliary Output Enable. A logic-high at AUXONA turns on the slot A auxiliary output.

38 12SA+

39 12SA-

40 12GA

MOSFETs connecting 3.3VAUXIN to 3.3AUXO_. V
logic and analog references of the MAX5957/MAX5958 and must always be connected to a supply
between 3V and 3.6V. Bypass 3.3AUXIN with a 0.1µF capacitor to GND.

Overcurrent Timeout Programming Input. Connect a resistor between 500Ω and 500kΩ from TIM to
GND to program t

Power-On-Reset Programming Input. Connect a resistor between 500Ω and 500kΩ from PORADJ to
GND to program the POR timing. Leave unconnected for a default value of 160ms. Connect
PORADJ to GND to completely skip the POR time delay for PWGD_. Connect PORADJ to GND to
completely skip the POR time delay for PWRGD_ assertion.

12V Supply Input. V
internal charge pump that drives the gates of the MOSFETs connected to 12G_. Bypass 12VIN with
a 1µF capacitor to GND.

Slot B Present-Detect Input. PRES-DETB accepts inputs from PRSNT#_# on a PCIe connector.
PRES-DETB has an internal 50kΩ pullup to 3.3VAUXIN. When PRES-DETB is low, the outputs follow
the command from ONB and AUXONB after a 4ms debounced time. When PRES-DETB goes from
low to high, all outputs of the respective slot shut down with no delay.

Slot B Forced-On Input. FONB has a 50kΩ internal pullup to 3.3VAUXIN. A logic-low on FONB turns
on all slot B outputs as long as the power inputs are within their operating range, regardless of the
status of the other input signals. Leave FONB unconnected for normal operation.

Slot A Present-Detect Input. PRES-DETA accepts inputs from PRSNT#_# on a PCIe connector.
PRES-DETA has an internal 50kΩ pullup to 3.3VAUXIN. When PRES-DETA is low, the outputs follow
the command from ONA and AUXONA after a 4ms debounced time. When PRES-DETA goes from
low to high, all outputs of the respective slot shut down with no delay.

Slot A Forced-On Input. FONA has a 50kΩ internal pullup to 3.3VAUXIN. A logic-low on FONA turns
on all slot A outputs as long as the power inputs are within their operating range, regardless of the
status of the other input signals. Leave FONA unconnected for normal operation.

Slot A 12V and 3.3V Outputs Enable. A logic-high at ONA turns on the 12V and 3.3V outputs of slot
A (see Table 2).

Slot A 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor
to 12SA+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot A 12V Negative Current-Sense Input. Connect 12SA- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.

Slot A 12V Gate-Drive Output. Connect 12GA to the gate of slot A’s 12V MOSFET. At power-up,
V

is raised to the internal charge-pump voltage level by a constant current.

12GA

3.3AUXIN

. Leave TIM unconnected for a default timeout of 11ms.

FAULT

drives the gates of the MOSFETs connected to 3.3G_. 12VIN powers an

12VIN

is also used to power the internal control

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 13

Pin Description (continued)

Detailed Description

The MAX5957/MAX5958 triple hot-plug controllers are
designed for PCIe applications. The devices provide
hot-plug control for 12V, 3.3V, and 3.3V auxiliary sup­plies for three PCIe slots. The MAX5957/MAX5958s’
logic inputs/outputs allow interfacing directly with the
system hot-plug-management controller or through an
SMBus with an external I/O expander. An integrated
debounced attention switch and present-detect signals
are included to simplify system design (Figure 1).

The MAX5957/MAX5958 drive six external n-channel
MOSFETs to control the 12V and 3.3V main outputs.
The 3.3V auxiliary outputs are controlled through inter­nal 0.2Ω n-channel MOSFETs. Internal charge pumps
provide a gate drive for the 12V outputs while the gate
drive of the 3.3V output is driven by the 12V input sup­ply. The 3.3V auxiliary outputs are completely indepen­dent from the main outputs with their own charge
pumps.

PIN NAME FUNCTION

41 3.3SA+

42 3.3SA-

43 3.3GA

44 FAULTA

45 PWRGDA

47 3.3AUXOA Slot A 3.3V Auxiliary Power-Supply Output
50 3.3AUXOB Slot B 3.3V Auxiliary Power-Supply Output

51 PWRGDB

52 FAULTB

53 3.3GB

54 3.3SB-

55 3.3SB+

56 12GB

Slot A 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to

3.3SA+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot A 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using
the Kelvin-sensing technique to ensure accurate current sensing.

Slot A 3.3V Gate-Drive Output. Connect 3.3GA to the gate of slot A’ s 3.3V MOSFET. At power-up,

is charged to 5.5V above the 3.3V supply by a constant current derived from V

V

3.3GA

V

‘s rise time is determined by the external gate capacitance.

3.3GA

Open-Drain Fault Output Signal. FAULTA latches active low whenever slot A outputs are shut down
due to a fault. A fault is either of:

• An overcurrent condition lasting longer than the overcurrent timeout.

• A device overtemperature condition.
If the fault is detected in the main outputs, FAULTA must be reset by toggling the ONA input. If the
fault is in the auxiliary output, FAULTA must be reset by toggling both ONA and AUXONA. For the
autorestart version, FAULTA is reset when the part initiates the next power-on cycle.
Open-Drain Power-Good Output. PWRGDA goes low 160ms after all outputs of slot A reach their
final value and the power MOSFETs are fully enhanced.

Open-Drain Power-Good Output. PWRGDB goes low 160ms after all outputs of slot B reach their
final value and the power MOSFETs are fully enhanced.
Open-Drain Fault Output Signal. FAULTB latches active low whenever the slot B outputs are shut
down due to a fault. A fault is either of:

• An overcurrent condition lasting longer than the overcurrent timeout.

• A device over temperature condition.
If the fault is detected in the main outputs, FAULTB must be reset by toggling the ONB input. If the
fault is in the auxiliary output, FAULTB must be reset by toggling both ONB and AUXONB. For the
autorestart version, FAULTB is reset when the part initiates the next power-on cycle.

Slot B 3.3V Gate-Drive Output. Connect 3.3GB to the gate of slot B’s 3.3V MOSFET. At power-up,
V

is charged to 5.5V above the 3.3V supply by a constant current derived from V

3.3GB

V

‘s rise time is determined by the external gate capacitance.

3.3GB

Slot B 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using
the Kelvin-sensing technique to ensure accurate current sensing.

Slot B 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to

3.3SB+ using the Kelvin-sensing technique to ensure accurate current sensing.

Slot B 12V Gate-Drive Output. Connect 12GB to the gate of slot B’s 12V MOSFET. At power-up,

is raised to the internal charge-pump voltage level by a constant current.

V

12GB

12VIN

12VIN

.

.

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

14 ______________________________________________________________________________________

Figure 1. Single-Channel Internal Block Diagram

R

TIM

t

FAULT

t

POR

OSCILLATOR

TIM

R

PORADJ

PORADJ

IN OUT 12VIN

DEBOUNCE

FAST

OSCILLATOR

BIAS, REFERENCES,

AND UVLO

MAX5957

PWRGD_ FAULT_

CHARGE

PUMP

108mV

12S_+

+

+

54mV

-

-

12S_-

5µA

10µA

10µA

150µA

120mA

100µA

+

+

20mV40mV

-

-

5µA

10µA

12G_

3.3S_+

3.3S_-

3.3G_

R

R

SENSE

SENSE

CONTROL LOGIC

MAIN-CHANNEL

CONTROL LOGIC

AUX-CHANNEL

UVLO

INPUT COMPARATOR AND

CHIP CONTROL LOGIC

AUXON_

ON_

PRES-DET_FON_

CONTROL LOGIC

MAIN-CHANNEL

CONTROL LOGIC

AUX-CHANNEL

150mA

+

V

REF

CHARGE

­PUMP

100µA

150µA

3.3AUXO

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 15

At power-up, the MAX5957/MAX5958 keep all the
external MOSFETs off until all supplies rise above their
respective UVLO thresholds. These devices keep the
internal MOSFETs off only until the 3.3VAUXIN supply
rises above its UVLO threshold. Upon a turn-on com­mand, the MAX5957/MAX5958 enhance the external
and internal MOSFETs slowly with a constant gate cur­rent to limit the power-supply inrush current. The
MAX5957/MAX5958 actively limit the current of all out­puts at all times and shut down the corresponding
channel if an overcurrent condition persists for longer
than a resistor-programmable overcurrent timeout (see
the

Fault Management

section). Thermal protection cir­cuitry also shuts down all outputs if the die temperature
exceeds +150°C. After an overcurrent or overtempera­ture fault condition, the MAX5957/MAX5958 latch off or
automatically restart after a restart time delay.

The power requirement for PCIe connectors is defined
by the PCIe card specification and summarized in
Table 1.

Startup

The main supply outputs can become active only after
all the following events have occurred:

•V

3.3AUXIN

is above its UVLO threshold.

•V

12VIN

and V

3.3SA+

are both above their UVLO

threshold.

• ON_ is driven high.

• PRES-DET_ is low for more than 4ms.

The auxiliary supply output is made available only after
the following events have occurred:

•V

3.3AUXIN

is above its UVLO threshold.

• AUXON_ is driven high.

• PRES-DET_ is low for more than 4ms.
The FON_ input overrides all other control signals and

turns on the respective slot when driven low, as long as
the UVLO thresholds have been reached. Table 2 sum­marizes the logic conditions required for startup. The aux­iliary supply input powers the internal control logic and
analog references of the MAX5957/MAX5958, so the main
supplies cannot be enabled, if V

3.3VAUXIN

is not present.
When an output is enabled, a programmable startup
timer (tSU) begins to count the startup time duration.

The value of t

SU

is set to 2x the fault timeout period

(t

FAULT

). R

TIM

externally connected from TIM to GND

sets the duration of t

FAULT

.

Table 1. Power Requirement for PCIe Connectors

POWER FAIL X1 CONNECTOR X4/8 CONNECTOR X16 CONNECTOR

3.3V

Voltage Tolerance ±9% (max) ±9% (max) ±9% (max)

Supply Current 3.0A (max) 3.0A (max) 3.0A (max)

Capacitive Load 1000µF (max) 1000µF (max) 1000µF (max)

12V

Voltage Tolerance ±8% (max) ±8% (max) ±8% (max)

Supply Current 0.5A (max) 0.5A (max) 0.5A (max)

Capacitive Load 300µF (max) 1000µF (max) 2000µF (max)

3.3V AUXILIARY

Voltage Tolerance ±9% (max) ±9% (max) ±9% (max)

Supply Current, Wake Enabled 375mA (max) 375mA (max) 375mA (max)

Supply Current, Nonwake Enabled 20mA (max) 20mA (max) 20mA (max)

Capacitive Load 150µF (max) 150µF (max) 150µF (max)

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

16 ______________________________________________________________________________________

Table 2. Control Logic Truth Table

*

PRES-DET_ high-to-low transition has a 4ms delay (t

DEG

).

Figure 2. Power-Up Timing, No Fault

Figure 3. 12V Power-Up Timing (Turn-On into Output
Overcurrent/Short Circuit)

ON_ AUXON_ FON_ PRES-DET

X X Low X On On

X X High High Off Off

Low Low High Low* Off Off

High Low High Low* On Off

Low High High Low* Off On

High High High Low* On On

12V_ AND 3.3V_

OUTPUTS

3.3VAUXO_AUXILIARY
OUTPUTS

V

PGTH12

V

V

PGTH3.3AUX

3.3AUXIN
RISING
EDGE

ON_,TH

PWRGD_ IS PULLED UP TO 3.3.
FAULT_ IS PULLED UP TO 3.3AUXIN.

V

PGTH3.3

t

POR_HL

ON_, AUXON_

12G_, 3.3G_

12VO_, 3.3VO_

3.3VAUXO_

PWRGD_

FAULT_

V

ON_,TH

V

12ILIM,TH

R

SENSE

3.3VAUXIN
RISING
EDGE

PWRGD_ IS PULLED UP TO 3.3VAUXO_.
FAULT_ IS PULLED UP TO 3.3VAUXIN.

A FAULT ON THE 3.3V OUTPUT OR 3.3VAUXO_ OUTPUT PRODUCES SIMILAR RESULTS.

2 x t

FAULT

ON_

12G_

12V OUTPUT
CURRENT

3.3VAUXO_

PWRGD_

FAULT_

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 17

12V and 3.3V Outputs Normal Operation

The MAX5957/MAX5958 monitor and actively limit the
current of the 12V and 3.3V outputs after the startup
period. Each output has its own overcurrent threshold.
If any of the monitored output currents rise above the
overcurrent threshold for a period t

FAULT

, FAULT_

asserts and the controller disengages both the 12V and

3.3V outputs for the particular slot (see the

Fault

Management

section).

3.3V Auxiliary Output Normal Operation

The auxiliary output current is internally monitored and
actively limited to the maximum current-limit value. An
overcurrent fault condition occurs when the output cur­rent exceeds the overcurrent threshold for longer than
t

FAULT

. A fault on an auxiliary channel causes all sup­plies of the affected channel to be disabled after a pro­grammable time period t

FAULT

.

A fault condition on a main channel (V

12VIN

or V

3.3VIN

)
causes all the channel’s main outputs to shut down
after the t

FAULT

period and then either latch off or auto-

matically restart after the t

RESTART(tRESTART

= 64 x

t

FAUALT

) period, depending on the device version. A

fault on any of the channel’s main outputs does not
affect the auxiliary channel (V

3.3AUXIN

).

Power-Good (PWRGD_)

Power-good (PWRGD_) is an open-drain output that
pulls low a time (t

POR_HL

) after all the outputs of the
respective slot are fully on. All outputs are considered
fully on when 3.3G_ has risen to V

PGTH3.3

, 12G_ has

risen to V

PGTH12

, and V

3.3AUXO_

is less than

V

PGTH3.3AUX

. t

POR_HL

is adjustable from 2.4ms to 1.5s

by connecting a resistor from PORADJ to GND. See the

Setting the Power-On Reset

and

Timeout Period

(t

POR_HL

)

sections. Connect PORADJ to GND to com-

pletely skip the POR time delay for PWRGD_ assertion.

Thermal Shutdown

When the die temperature goes above (TSD) +150°C, an
overtemperature fault occurs and the MAX5957/
MAX5958 shut down all outputs. The devices wait for the
junction temperature to decrease below T

SD

- hysteresis

before entering fault management (see the

Fault

Management

section).

Fault Management

A fault occurs when an overcurrent or 12G_ or 3.3G_
below the power-good threshold lasts longer than
t

FAULT

or when the device experiences an overtemper-

ature condition:

• A fault on a main output (12V or 3.3V) shuts down

both main outputs of the respective slot. The 3.3V
auxiliary is not affected.

• A fault on the 3.3V auxiliary output shuts down all

three outputs of the respective slot.

The MAX5957A/MAX5958A automatically restart from a
fault shutdown after the t

RESTART

period while the
MAX5957L/MAX5958L latch off. If an overcurrent fault
occurred on a main output, bring ON_ low for at least
t

RESET

(100µs) and high again to reset the fault and
restart the outputs. If the overcurrent fault occurred on
an auxiliary output or an overtemperature fault
occurred, bring both ON_ and AUXON_ low for a mini­mum of t

RESET

to reset the fault. Toggle ON_ or only
AUXON_ to reset the fault condition. If ON_ and
AUXON are toggled before t

RESTART

time counting has
elapsed, the MAX5957L/MAX5958L store the informa­tion and restart when the delay is finished. The
MAX5957A/MAX5958A (autoretry versions) restart all
channels automatically after t

RESTART

.

Figure 4. 12 Output Overcurrent/Short Circuit During Normal
Operation

V

12ILIM,TH

R

SENSE

t

FAULT

PWRGD_ IS PULLED UP TO 3.3VAUXO_.
FAULT_ IS PULLED UP TO 3.3VAUXIN.

A FAULT ON THE 3.3V OUTPUT OR 3.3VAUXO_ OUTPUT PRODUCES SIMILAR RESULTS.

12G_

12V OUTPUT
CURRENT

PWRGD_

FAULT_

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

18 ______________________________________________________________________________________

Debounced Logic Gate

(INPUT_ and OUTPUT_)

INPUT1, INPUT2, and INPUT3 accept inputs from
mechanical switches. The corresponding outputs are
OUTPUT1, OUTPUT2, and OUTPUT3. OUTPUT_ is
debounced for 4ms. When INPUT_ goes from high to
low, OUTPUT_ goes low immediately and stays low for
at least 4ms. After the debounce time, OUTPUT_ fol­lows INPUT_. If INPUT_ goes from low to high, OUT­PUT_ goes high immediately and stays high for at least
4ms. After the debounce time, OUTPUT_ follows
INPUT_. Figure 5 shows the timing diagram describing
the INPUT_/OUTPUT_ debounced feature.

Present-Detect and Forced-On Inputs

(PRES-DET_, FON_)

PRES-DET_ input detects the PRSNT#2 pin on a PCIe
connector. When the card is plugged in, PRES-DET_
goes low and allows the turn-on of the outputs of the
respective slot after a 4ms debounced time. When the
card is removed, an internal 50kΩ pullup resistor forces
PRES-DET_ high and the respective slot is shut down
with no delay. PRES-DET_ works in conjunction with
ON_ and AUXON_ and only enables the device when
ON_ and AUXON_ are high.

A logic-low on FON_ forces the respective slot (main
supplies and auxiliary) to turn on regardless of the sta­tus of the other logic inputs, provided the UVLO thresh­olds are exceeded on all the inputs.

Active Current Limits

Active current limits are provided for all three outputs of
the three slots (slot A, slot B, and slot C). Connect a
current-sense resistor between 12S_+ and 12S_- to set
the current limit for the 12V outputs. The current limit is
set to 54mV / R

SENSE12

. Connect a current-sense resis­tor between 3.3S_+ and 3.3S_- to set the current limit
for the 3.3V main outputs to 20mV / R

SENSE3.3

. For the
auxiliary output (3.3VAUXO_) the current limit is fixed at
450mA in the MAX5957 and 700mA in the case of the
MAX5958.

When the voltage across R

SENSE12

or R

SENSE3.3

reaches the current-limit threshold voltage, the
MAX5957/MAX5958 regulate the gate voltage to main­tain the current-limit threshold voltage across the sense
resistor. If the current limit lasts for t

FAULT

, then an
overcurrent fault occurs. The MAX5957/MAX5958 shut
down both the 12V and 3.3V outputs and assert the
FAULT_ output of the respective slot.

When the auxiliary output reaches the current limit for
longer than t

FAULT

, a fault occurs and the device shuts

down all outputs and asserts FAULT of the respective slot.

UVLO Threshold

The UVLO thresholds prevent the internal auxiliary
MOSFETs and the external main channel MOSFETs
from turning on if V

12VIN

, V

3.3VIN

, and V

3.3VAUXIN

are
not present. Internal comparators monitor the main
supplies and the auxiliary supply and keep the gate­drive outputs (12GA, 12GB, 12GC, 3.3GA, 3.3GB, and

3.3GC) low until the supplies rise above their UVLO
threshold. The 12V main supply is monitored at 12VIN
and has a UVLO threshold of 10V. The 3.3V main sup­ply is monitored at 3.3SA+ and has a UVLO threshold
of 2.65V. The auxiliary supply is monitored at

3.3AUXIN and has a 2.65V UVLO threshold. For either
main channels to operate, V3.3AUXIN must be above
its UVLO threshold.

Figure 5. INPUT_ and OUTPUT_ Debounced Feature

INPUT

t

DBC

DEBOUNCED

OUTPUT

t

DBC

t

DBC

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 19

LATCH-OFF

Figure 6. Fault Management Flowchart

OPTION?

SHUT DOWN

12V AND 3.3V OUTPUTS.

ASSERT FAULT_

N

N

STAY WAITING FOR

t

RESTART

ON_ TOGGLED

HIGH ≥ LOW ≥ HIGH

N

3.3VAUXIN IS OK,
AUXON_ IS HIGH,

PRES_DET IS LOW

ON_ AND

AUXON_ TOGGLED

HIGH ≥ LOW

≥ HIGH

Y

RESET FAULT_

Y

Y

N

Y

RESET FAULT_

N

POWER ON

AUXILIARY OUTPUT.

FAULT_ AND PWRGD_ ARE

HIGH IMPEDANCE

FAULT

STILL PRESENT?

N

t

ELAPSED?

FAULT

MAIN INPUTS ARE

OK, ON_ IS HIGH

N

Y

Y

ENABLE CHARGE ON
INTERNAL AUXILIARY

MOSFET DRIVING 3.3AUXO_.

START COUNTING t

RESET t

COUNTER

START COUNTING

SU

FAULT

t

FAULT

ENABLE CHARGE

ON 3.3G_ AND 12G_.

START

COUNTING t

START PGOOD

THRESHOLD

MONITORING

RESET PWRGD_

Y

SU

FAULT ON 12V

OR 3.3V OUTPUTS

N

tSU

ELAPSED?

N

N

ALL PGOOD

THRESHOLDS

REACHED?

Y

MAIN OUTPUTS OK?

Y

Y

AUX OUTPUT OK?

NO FAULT DETECTED

N

ARE ALL

NO FAULT

DETECTED

Y

tSU

ELAPSED?

N

ASSERT PWRGD_

AFTER t

DELAY

N

POR_HL

Y

Y

LATCH-OFF

OPTION?

SHUT DOWN ALL OUTPUTS.

ASSERT FAULT_.

STAY WAITING

FOR t

RESTART

Y

t

ELAPSED?

FAULT

N

FAULT

STILL PRESENT?

N

Y

START COUNTING

t

FAULT

RESET t

COUNTER

FAULT

N

FAULT ON 3.3AUXO_?

Y

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

20 ______________________________________________________________________________________

External MOSFET Gate Drivers

(12G_ and 3.3G_)

The gate drive for the external MOSFETs is provided at
12GA, 12GB, 12GC, 3.3GA, 3.3GB, and 3.3GC. 12G_
is the gate drive for the 12V main supply and is boost­ed to 5.3V above V

12VIN

by its internal charge pump.
During turn-on, 12G_ sources 5µA into the external
gate capacitance to control the turn-on time of the
external MOSFET. During turn-off, 12G_ sinks 150µA
from the external gate capacitance to quickly turn off
the external MOSFET. During short-circuit events, an
internal 120mA current sink activates to rapidly bring
the load current into the regulation limits.

3.3G_ is the gate drive for the 3.3V main supply’s MOS­FET and is driven to 5.5V above the 3.3V main supply.
The power for 3.3G_ is supplied from 12VIN and has no
internal charge pump. During turn-on, 3.3G_ sources
5µA into the external gate capacitance to control the
turn-on time of the external MOSFET. During turn-off,

3.3G_ sinks 150mA to quickly turn off the external
MOSFET. During short-circuit events, an internal
120mA current sink activates to rapidly turn off the
appropriate external MOSFET.

Auxiliary Supply (3.3VAUXIN)

3.3VAUXIN provides power to the auxiliary outputs as
well as the internal logic and references. The drains of
the internal auxiliary MOSFETs connect to 3.3AUXIN
through internal sense resistors and the sources con­nect to the auxiliary outputs (3.3VAUXO_). Both
MOSFETs have typical on-resistance of 0.2Ω. Each
channel’s internal charge pump boosts the gate-drive
voltage to fully turn on the internal n-channel MOSFETs.
The auxiliary supplies have an internal current limit set
to 450mA (MAX5957), 700mA (MAX5958).

Applications Information

Setting the Power-On Reset

t

FAULT

is the time an overcurrent or overtemperature
fault must remain for the MAX5957/MAX5958 to disable
the main or auxiliary channels of a particular slot.
Program the fault timeout period (t

FAULT

) by connect-

ing a resistor (R

TIM

) from TIM to GND. t

FAULT

can be

calculated by the following equation:

t

FAULT

= (166ns / Ω) x R

TIM

The t

FAULT

programmed time duration must be chosen
according to the total capacitance load connected to
the 12G_ and 3.3G_ pins. To properly power up the
main supply outputs, the following constraints need to
be taken:

tSU≥ (V

GATE

x C

LOAD

) / I

CHG

where t

SU

= 2 x t

FAULT

and where:

•I

CHG

= 5µA.

•V

GATE

= 4.8V + V

12VIN

for 12G_ and V

GATE

= 6.8V

+ V

3.3VIN

for 3.3G_.

•C

LOAD

is the total capacitance load at the gate.

Maximum and minimum values for R

TIM

are 500Ω and
500kΩ, respectively. Leave TIM floating for a default
t

FAULT

of 10ms.

Timeout Period (t

POR_HL

)

t

POR_HL

is the time from when the gate voltages of all

outputs of a slot reach their power-good threshold to
when PWRGD_ pulls low. Program the POR timeout
period (t

POR

) by connecting a resistor (R

PORADJ

) from

PORADJ to GND. t

POR_HL

can be calculated by the fol-

lowing equation:

t

POR_HL

= (2.5µs / Ω) x R

PORADJ

Maximum and minimum values for R

PORADJ

are 500Ω
and 500kΩ, respectively. Leave PORADJ floating for a
default t

POR

of 150ms. Connect PORADJ to GND in

order to completely skip the power-on delay time prior
to the PWRGD_ assertion.

Component Selection

Select the external n-channel MOSFET according to the
applications current requirement. Limit the switch
power dissipation by choosing a MOSFET with an
R

DS_ON

low enough to have a minimum voltage drop at

full load. High R

DS_ON

causes larger output ripple if

there are pulsed loads. High R

DS_ON

can also trigger
an external undervoltage fault at full load. Determine
the MOSFET’s power-rating requirement to accommo­date a short-circuit condition on the board during start­up. Table 3 lists the MOSFETs and sense resistor
manufacturers.

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 21

Additional External Gate Capacitance

External capacitance can be added from the gate of
the external MOSFETs to GND to slow down the dV/dt
of the 12V and 3.3V outputs. The maximum gate
capacitance load at 12G_ and 3.3G_ must be consis­tent with the conditions described in the

Setting the

Power-On Reset

section.

Maximum Load Capacitance

Large capacitive loads at the 12V output, the 3.3V out­put, and the 3.3V auxiliary output can cause a problem
when inserting discharged PCI cards into live back­planes. A fault occurs if the time needed to charge the
capacitance of the board is greater than the typical
startup time (2 x t

FAULT

). The MAX5957/MAX5958 with­stand large capacitive loads due to their adjustable
startup times and adjustable current-limit thresholds.
Calculate the maximum load capacitance as follows:

C

LOAD

< (tSUx I

LIM

) / V

OUT

V

OUT

is either the 3.3V output, the 12V output, or the

3.3V auxiliary output for slot A, slot B, or slot C.

Input Transients

The 12V input (12VIN), the 3.3V input (3.3SA+), and the

3.3V auxiliary (3.3AUXIN) must be above their UVLO
thresholds before startup can occur. Input transients
can cause the input voltage to sag below the UVLO
threshold. The MAX5957/MAX5958 reject transients on
the input supplies that are shorter than 4µs (typ).

Because some load fault conditions can cause voltage
transients to propagate to the supply inputs with dura­tion of greater than 4µs, it is recommended that a small
Schottky diode be placed in series with the 12VIN pin
connection, upstream of the 1µF bypass capacitor. This
provides a hold-up supply that will prevent the 12VIN
input from dropping below V

12UVLO

during severe tran-

sients. See the

Typical Application Circuit

.

Table 3. Component Manufacturers

COMPONENT MANUFACTURER PHONE WEBSITE

Sense Resistor

MOSFETs

Vishay-Date 402-564-3131 www.vishay.com

IRC 704-264-8861 www.irctt.com

Fairchild 888-522-5372 www.fairchildsemi.com

International Rectifier 310-322-3331 www.irf.com

Motorola 602-244-3576 www.mot-sps.com/ppd

Vishay-Siliconix — www.vishay.com

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

22 ______________________________________________________________________________________

Typical Application Circuit

PCI EXPRESS

SLOT_

PRSNT1#

+12V

GND

PWRGD

3.3VAUX

+3.3V

12G_

PWRGD_

10kΩ

3.3VAUXO_

GND

3.3G_

ONE OF THREE SLOTS SHOWN

R1

8mΩ

0.1µF

12S_-

3.3S_-

V

3.3VMAIN

5mΩ

12S_+

3.3S_+

R2

3.3VAUXIN

PRES-DET_

0.1µF

V

3.3VAUX

2.2µF

MAX5957
MAX5958

FAULT_

12VIN

V

12VMAIN

IN5819

=

R

PORADJ

OPEN

PORADJ

AUXON_ ON_ INPUT_ OUTPUT_

FON_

R

TIM

OPEN

=

TIM

V

3.3VAUXIN

PRSNT2#

MRL

10kΩ

MAX7313ATG

16-BIT I/O

LEDs

2

EXPANDER

2

ATTENTION

SWITCH

INTSMBus AO–A2

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

______________________________________________________________________________________ 23

Pin Configuration

Chip Information

PROCESS: BiCMOS

TOP VIEW

3.3GA

FAULTA

PWRGDA

PGND

3.3AUXOA

3.3AUXIN

3.3AUXIN

3.3AUXOB

PWRGDB

FAULTB

3.3GB

3.3SB-

3.3SB+

12GB

PRES-DETA

FONA

OUTPUT3

INPUT3

ONA

AUXONA

12SA+

12SA-

12GA

3.3SA+

3.3SA-

42

41 40 39 38 37 36 35 34 33 32 31 30 29

43

44

45

46

47

48

49

50

51

52

53

54

55

+

56

1 2 3 4 5 6 7 8 9 1011121314

MAX5957
MAX5958

FONB

PRES-DETB

N.C.

28

27

26

25

24

23

22

21

20

19

18

17

16

15

12VIN

GND

PORADJ

TIM

PGND

3.3VAUXIN

3.3AUXOC

PWRGDC

FAULTC

3.3GC

3.3SC-

3.3SC+

12GC

12SC-

12SB-

12SB+

ONB

AUXONB

INPUT2

INPUT1

OUTPUT1

OUTPUT2

THIN QFN

GND

FONC

ONC

PRES-DETC

12SC+

AUXONC

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

24 ______________________________________________________________________________________

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages

.)

E

2

E/

D/2

D

A1AA2

DETAIL

(ND-1) X

A

e

(NE-1) X

e

k

32, 44, 48L QFN.EPS

D2/2

C

D2

L

b

C

L

L

e

1

F

2

e

L

k

C

L

L

E2/2

C

L

E2

e

PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm

21-0144

MAX5957/MAX5958

Triple PCI Express, Hot-Plug Controllers

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________

25

© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages

.)

PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm

21-0144

2

F

2