FM31276-G 查看數據表（PDF） - Cypress Semiconductor

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FM31276-G

5V Integrated Processor Companion with Memory

Cypress Semiconductor 

FM31278/276 – 5V I2C Companion

A1, A0

SCL

SDA

2-Wire

Interface

LockOut

F-RAM

Array

LockOut

RST

PFI

CAL/PFO

VDD

2.5V -

+

VBAK

Watchdog

LV Detect

Special

Function

Registers

S/N

+

- 1.2V

RTC Cal.

512Hz

Switched Power

RTC Registers

RTC

Event

Counters

X1

X2

CNT1

CNT2

Nonvolatile

Battery Backed

Pin Name

A0, A1

CNT1,

CNT2

CAL/PFO

X1, X2

/RST

SDA

SCL

PFI

VBAK

VDD

VSS

Type

Input

Input

Output

I/O

I/O

I/O

Input

Input

Supply

Supply

Supply

Figure 1. Block Diagram

Pin Descriptions

Pin Description

Device select inputs are used to address multiple memories on a serial bus. To select the

device the address value on the two pins must match the corresponding bits contained in

the device address. The device select pins are pulled down internally.

Event Counter Inputs: These battery-backed inputs increment counters when an edge is

detected on the corresponding CNT pin. The polarity is programmable. These pins

should not be left floating. Tie to ground if these pins are not used.

In calibration mode, this pin supplies a 512 Hz square-wave output for clock calibration.

In normal operation, this is the early power-fail output.

32.768 kHz crystal connection. When using an external oscillator, apply the clock to X1

and a DC mid-level to X2 (see Crystal Oscillator section for suggestions).

Active low reset output with weak pull-up. Also input for manual reset.

Serial Data & Address: This is a bi-directional line for the two-wire interface. It is open-

drain and is intended to be wire-OR‟d with other devices on the two-wire bus. The input

buffer incorporates a Schmitt trigger for noise immunity and the output driver includes

slope control for falling edges. A pull-up resistor is required.

Serial Clock: The serial clock line for the two-wire interface. Data is clocked out of the

part on the falling edge, and in on the rising edge. The SCL input also incorporates a

Schmitt trigger input for noise immunity.

Early Power-fail Input: Typically connected to an unregulated power supply to detect an

early power failure. This pin should not be left floating.

Backup supply voltage: A 3V battery or a large value capacitor. If no backup supply is

used, this pin should be tied to ground and the VBC bit should be cleared. The trickle

charger is UL recognized and ensures no excessive current when using a lithium battery.

Supply Voltage

Ground

Document Number: 001-86393 Rev. *B

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