SUMMIT SMH4812G, SMH4812S Datasheet

SUMMIT

MICROELECTRONICS, Inc.

Distributed Power Hot-Swap Controller

FEATURES

SMH4812

Preliminary

!!

! Soft Starts Main Power Supply on Card Insertion

!!

or System Power Up

!!

! Senses Card Insertion via Short Pins or Ejector

!!

Switches

!!

! Master Enable to Allow System Control of Power

!!

Up or Down

""

" Can be used as a Temperature Sense Input

""

!!

! Programmable Independent Controls of a DC/DC

!!

Converter

""

" Not Enabled until Host Supply Fully Soft

""

Started

""

" Programmable Time Delay

""

""

" Available Input to hold off Dependant Enables

""

until Conditions are Satisfied

!!

! Highly Programmable Circuit Breaker

!!

""

" Programmable Quick-Trip

""

""

" Programmable Current Limiting

""

""

" Programmable Duty Cycle Times

""

""

" Programmable Over-current Filter

""

TM

Values

SIMPLIFIED APPLICATION DRAWING

!!

! Programmable Host Voltage Fault Monitoring

!!

""

" Programmable Under-Voltage Hysteresis

""

""

" Programmable UV/OV Voltage Filter

""

""

" Programmable Fault Mode: Latched or Duty

""

Cycle

!!

! Programmable Forced Shutdown Timer

!!

!!

! 2.5V and 5.0V Reference Outputs

!!

""

" Eliminates the Need for Other Primary Volt-

""

ages

""

" Easy Expansion of External Monitor Func-

""

tions

!!

! Supply Range +20VDC to >+500VDC

!!

0V

Disable/Enable

ENPG

FS#

FAULT#

Pin Detect

VDD

PD1#

UV

SMH4812

PG2#

5.0VREF

Pin Detect

OV

PD2#

VSS

CBSENSE

VGATE

2.5VREF

–48V

©SUMMIT MICROELECTRONICS, Inc., 2000 • 300 Orchard City Dr., Suite 131 • Campbell, CA 95008 • Phone [phone] • FAX [phone] • www.summitmicro.com

Characteristics subject to change without notice

2055 4.0 12/22/00

DC/DC

2055 SAD 1.1

1

DESCRIPTION

SMH4812

Preliminary

The SMH4812 is designed to control hot swapping of plug­in cards operating from a single supply, which can have an
output range from 20V to 500V. The SMH4812 hot-swap
controller provides under-voltage and over-voltage moni­toring of the host power supply, it drives an external power
MOSFET switch that connects the supply to the load, and
it protects against over-current conditions that might dis­rupt the host supply. When the input and output voltages
to the SMH4812 controller are within specification it pro-

FUNCTIONAL BLOCK DIAGRAM

VDD

DRAIN

SENSE

16

1

50kΩ

12VREF

+

–

vides a Power Good logic output that may be used to
enable a DC-DC converter. Additional features of the
device include: temperature sense or master enable
input, 2.5V and 5V reference outputs for expanding moni­tor functions, two Pin-Detect enable inputs for fault protec­tion, and duty-cycle or latched over-current protection
modes. All of these features can be programmed by the
factory according to the user's requirements.

ENPG

14

PROGRAMM-

ABLE

SHUTDOWN

TIMER

13

12

11

FS#

2.5VREF

5.0VREF

EN/TS

PD1#
PD2#

VSS

CBSENSE

2

UV

OV

50kΩ

50kΩ

3

4
5

9

10

12V

5V

8

PROGRAMM-

7

Programmable

Quick Response

2.5V

ABLE

DELAY

50mV

Ref. Voltage

+

–

+

–

+

–

+

–

+

–

FILTER

DUTY

CYCLE

TIMER

2055 4.0 12/22/00

50kΩ

PROGRAMM-

ABLE

DELAY

15

PG#

VGATE
SENSE

2

VGATE

6

FAULT#

2055 BD 3.0

SUMMIT MICROELECTRONICS, Inc.

PIN CONFIGURATION

SMH4812

Preliminary

SS

1
2
3
4
5
6
7
8

DRAIN SENSE

VGATE

EN/TS

PD1#
PD2#

FAULT#

CBSENSE

V

PIN DESCRIPTIONS

DRAIN SENSE (1)

The DRAIN SENSE input monitors the voltage at the drain
of the external power MOSFET switch with respect to VSS.
An internal 10µA source pulls the DRAIN SENSE signal
towards the 5V reference level. DRAIN SENSE must be
held below 2.5V to enable the PG outputs.

EN/TS (3)

The Enable/Temperature Sense input is the master en­able input. If EN/TS is less than 2.5V, VGATE will be
disabled. This pin has an internal 200kW pull-up to 5V.

V

16
15
14
13
12
11
10

PG#
ENPG
FS#

2.5V
5V
OV
UV

9

2055 PCon 2.0

DD

REF

REF

OV (10)

The OV pin is used as an over-voltage supply monitor,
typically in conjunction with an external resistor ladder.
VGATE will be disabled if OV is greater than 2.5V. A filter
delay is available on the OV input.

VGATE (2)

The VGATE output activates an external power MOSFET
switch. This signal supplies a constant current output
(100µA typical), which allows easy adjustment of the
MOSFET turn on slew rate.

PD1#, PD2# (4, 5)

These are logic level active low inputs that can optionally
be employed to enable VGATE and the PG outputs when
they are at VSS. These pins each have an internal 50kW
pull-up to 5V.

CBSENSE (7)

The circuit breaker sense input is used to detect over­current conditions across an external, low value sense
resistor (RS) tied in series with the Power MOSFET. A
voltage drop of greater than 50mV across the resistor for
longer than t

will trip the circuit breaker. A program-

CBD

mable Quick-Trip sense point is also available.

UV (9)

The UV pin is used as an under-voltage supply monitor,
typically in conjunction with an external resistor ladder.
VGATE will be disabled if UV is less than 2.5V. Program­mable internal hysteresis is available on the UV input,
adjustable in increments of 62.5mV. Also available is a
filter delay on the UV input.

FAULT# (6)
FAULT# is an open-drain, active-low output that indicates

the fault status of the device.

5VREF (11)

This is a precision 5V output reference voltage that may be
used to expand the logic input functions on the SMH4812.
The reference output is with respect to VSS.

2.5VREF (12)

This is a precision 2.5V output reference voltage that may
be used to expand the logic input functions on the
SMH4812. The reference output is with respect to VSS.

FS# (13)

The Forced Shutdown (FS#) pin is an active low input that
causes VGATE and PG outputs to be shut down at any
time after an internal hold-off timer has expired. The hold­off timer allows supervisory circuits on the secondary side
(which are not powered up initially) to control shut down of
the SMH4812 via an opto-isolator. This input has no pull­up resistor.

SUMMIT MICROELECTRONICS, Inc.

2055 4.0 12/22/00

3

SMH4812

Preliminary

ENPG (14)

The ENPG input controls the PG# output. When ENPG is
pulled low the PG# output is immediately placed in a high
impedance state. If ENPG is driven high then the PG#
output will immediately be driven low.

PG# (15)

PG# is an open-drain, active-low output with no internal
pull-up resistor. It can be used to switch a load or enable
a DC/DC converter. PG# is enabled immediately after
VGATE reaches V

– VGT and the DRAIN SENSE

DD

voltage is less than 2.5V. Voltage on these pins cannot
exceed 12V, as referenced to V

SS.

VDD (16)

VDD is the positive supply connection. An internal shunt
regulator connected between VDD and VSS develops ap­proximately 12V that supplies the SMH4812. A resistor
must be placed in series with the VDD pin to limit the
regulator current (RD in the application illustrations).

V

(8)

SS

VSS is connected to the negative side of the supply.

4

2055 4.0 12/22/00

SUMMIT MICROELECTRONICS, Inc.

ABSOLUTE MAXIMUM RATINGS*

SMH4812

Preliminary

Temperature Under Bias ...................... –55°C to 125°C

Storage Temperature ........................... –65°C to 150°C

Lead Solder Temperature (10 secs) ................... 300 °C

Terminal Voltage with Respect to VSS:

V

................................. –0.5V to V

DD

DD

OV, UV, DRAIN SENSE,

FS#, CBSENSE .....–0.5V to VDD+0.5V

PD1#, PD2#, ENPG, EN/TS ......... 10V

FAULT#, PG# ........–0.5V to VDD+0.5V

VGATE ................................ VDD+0.5V

AC OPERATING CHARACTERISTICS

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*COMMENT

Stresses 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
outside those listed in the operational sections of this specification is not
implied. Exposure to any absolute maximum rating for extended
periods may affect device performance and reliability.

5sµ

05

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*

051sµ
004sµ

05sµ

052sµ
005sµ

0051sµ

*

5

02sm
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*

—

5sm

08sm

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5.0sm

5sm

*

08

061sm

2055 Prog Table

sµ

sm

sm

* = Default value

SUMMIT MICROELECTRONICS, Inc.

2055 4.0 12/22/00

5

DC OPERATING CHARACTERISTICS

(Over Recommended Operating Conditions; Voltages are relative to VSS, except VGT)

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V

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SMH4812

Preliminary

DD

FER

V

V

2055 Elect Table

RECOMMENDED OPERATING CONDITIONS

Temperature –40°C to 85°C.

6

2055 4.0 12/22/00

SUMMIT MICROELECTRONICS, Inc.