SMS64

Preliminary

Summit Microelectronics, Inc

2060 2.22 10/09/03

4

PIN DESCRIPTIONS

Pin

Number

Pin

Type

Pin Name

Pin Description

6

PWR

5

PWR

4

PWR

3

PWR

2

PWR

1

PWR

The VCC inputs have two functions on the SMS64. They are used as the

power supply inputs and as such are diode-OR’ed so that at any point in time the

highest potential input will be the power source for the SMS64. So long as one of

the inputs is at or above 1V the RESET outputs will be active. For proper device

operation, including sequencing, at least one of the pins must be at or above

2.7V.

Each VCC input can be programmed as a voltage sensing input. It will only be

comparator’s source input will be switched to its corresponding VM input.

7

PWR

VCC_CAP

VCC_CAP is a charge storage connection to the SMS64’s internal power

supply. For most applications this pin is tied to a 10µF capacitor.

10

I

A2

11

I

A1

The address pins are biased either to VCC_CAP or GND.

When

communicating with the SMS64 over the 2-wire bus these pins provide a

mechanism for assigning a unique bus address.

A2 and A1 are internally

connected to VCC through a 100K

Ω resistor.

12

I

CS#

The Chip Select input is used solely for enabling communication on the 2-wire

bus. In order to write or read the registers or the memory array the CS# input

must be low. CS# is internally connected to VCC through a 100K

Ω resistor.

13

I

SCL

The SCL input is used to clock data into and out of the memory array. In the

write mode, data must remain stable while SCL is HIGH. In the read mode, data

is clocked out on the falling edge of SCL.

14

I/O

SDA

SDA is the bidirectional serial data pin. It is configured as an open drain

output and will require a pull-up resistor to VCC_CAP or a higher potential system

supply.

15

PWR

GND

GND is the ground for both the analog and digital portions of the internal

circuitry. It is internally tied to pin 24. (Both pins should be tied to system ground).

16

I

FS#

The force shutdown input is used to immediately turn off all PUP outputs. FS#

is internally connected to VCC through a 100K

Ω resistor.

17

I

PWR_

ON/OFF

The PWR_ON/OFF input is used to initiate power-on and power-off

sequencing. When the input is high and all of the programmed preconditions are

met, the SMS64 will power-on.

If the input is taken low, the SMS64 will begin the power-off operation. If

programmed to do so, the SMS64 will sequence off the PUP outputs either in the

power-on order or reverse order. PWR_ON/OFF is internally connected to VDD

through a 100K

Ω resistor.

18

I

MR#

MR# is the manual reset input. When MR# is taken low the RST_A# and

RST_B# outputs will be driven low. The RST outputs will stay low so long as the

no other reset conditions exist).

MR# must be low in order to write to the configuration registers and high to

write to the memory array (see descriptions on page 16).

MR# is internally

connected to VCC through a 100k

Ω pull-up resistor.

PIN DESCRIPTIONS