SMH4804 Datasheet, PDF (11/41 Pages) Summit Microelectronics, Inc. – -48V Programmable Hot Swap Sequencing Power Controller

SMH4804
Pin Descriptions
Pin Number Pin Number
(28-Pin SOIC) (48-Pin TQFP)
10
10
11
12
12
13
13
15
14
17
15
20
16
22
17
24
18
25
19
26
Pin Type
(I/O)
Pin Name
Description
I
MODE
The state of the MODE signal determines how fault
conditions are cleared. The device is in latched mode
when this pin is low, and in cycle mode when the pin
is high or floating.
I
SCL
SCL is the serial clock input. This pin has an internal
50KΩ pull-up to 5V.
I
CBSENSE
The circuit breaker sense input is used to detect over-
current conditions across an external, low value sense
resistor (R_S) tied in series with the Power MOSFET. A
voltage drop of greater than 50mV across the resistor
for longer than t_CBD trips the circuit breaker. A
programmable Quick-Trip™ sense point is also
available.
I
A1
The A1 input works in conjunction with the A0 and A2
inputs. Together these inputs are used for decoding
multiple devices on the serial bus. The A1 input has an
internal 50KΩ pull-up to 5V.
I
VSS
This is connected to the negative side of the supply.
I
UV
The UV pin is used as an under-voltage supply
monitor, typically in conjunction with an external
resistor ladder. VGATE is 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.
I
A2
The A2 input works in conjunction with the A0 and A1
inputs. Together these inputs are used for decoding
multiple devices on the serial bus. The A2 input has an
internal 50KΩ pull-up to 5V.
I
OV
The OV pin is used as an over-voltage supply monitor,
typically in conjunction with an external resistor
ladder. VGATE is disabled if OV is greater than 2.5V.
A filter delay is available on the OV input.
I
FS#
The Forced Shutdown (FS#) pin is an active low input
that causes VGATE and the PG[4:1]# outputs to be
shut down at any time after an internal shutdown timer
has expired. The shutdown timer allows supervisory
circuits on the secondary side (which are not powered
up initially) to control shut down of the SMH4804 via
an opto-isolator. This input has no pull-up resistor.
O
5VREF
This is a precision 5V output reference voltage that
may be used to expand the logic input functions on the
SMH4804. The output reference voltage is with
respect to V_SS.
Table 1. SMH4804 Pin Descriptions (Continued)
Summit Microelectronics
2050 3.7 10/30/02
11