M41T00AUD datasheet(6/44 Pages) STMICROELECTRONICS

6 / 44 page

Description

M41T00AUD

6/44

Description

The M41T00AUD is a low power serial real-time clock (RTC) with an integral audio section

with tone generator and 300mW output amplifier. The RTC is a superset of the M41T00 with

enhancements such as a precision reference for switchover, an oscillator fail detect circuit

and storing of the time at power down. The audio section includes a summing amplifier

(inverting) at the input. An 8kHz low pass filter follows that with a 16 step programmable gain

stage next. A 256 or 512Hz audio tone can be switched into the filter in place of the input

signal. From the gain stage, the 300mW amplifier drives the output pins.

The M41T00AUD has a built-in power sense circuit which detects power failures and

automatically switches to the backup input when VCC is removed. Backup power can be

supplied by a capacitor or by a battery such as a Lithium coin cell. The device includes a

trickle charge circuit for charging the capacitor.

The RTC includes a built-in 32.768kHz oscillator controlled by an external crystal. Eight

the M41T00. Two additional registers control the audio section and the trickle charger. The

10 registers (see Table 2) are accessed over a 400kHz I2C bus. The address register

increments automatically after each byte READ or WRITE operation thus streamlining

transfers by eliminating the need to send a new address for each by to be transferred.

Typical data retention times will be in excess of 5 years with a 50mAh 3V lithium cell (see

RTC DC characteristics, Table 12 for more information).

Figure 1.

Logic diagram

OSCI

VCC

M41T00AUD

VSS

SCL

OSCO

IRQ/FT/OUT

SDA

VBIAS

AIN

VBACK

AOUT+

AOUT–

FBK

ai13322

M41T00AUD Datasheet(PDF) 6 Page - STMicroelectronics