General Description

The MAX6916 provides all the features of a real-time

clock (RTC) plus a microprocessor supervisory circuit,

NV RAM controller, and backup-battery monitor func-

tion. In addition, 96 x 8 bits of static RAM are available

for scratchpad storage. The MAX6916 communicates

with a microprocessor through an SPI™-bus-compati-

ble serial interface.

The real-time clock/calendar provides seconds, min-

utes, hours, day, date, month, and year information.

The end of the month date is automatically adjusted for

months with fewer than 31 days, including corrections

for leap years through 2099. The clock operates in

either 24hr or 12hr format with an AM/PM indicator. A

time/date-programmable alarm function is provided

with an open-drain, active-low alarm output.

The microprocessor supervisory circuit features an

open-drain, active-low reset available in three different

reset thresholds. A manual reset input and a watchdog

function are included as well.

The NV RAM controller provides power for external SRAM

from a backup battery plus chip-enable gating. The back-

up battery also provides data retention of the on-board 96

x 8 bits of RAM. An open-drain, active-low, battery-on sig-

nal alerts the system when operating from a battery.

The battery-test circuitry periodically tests the backup

battery for a low-battery condition. An optional external

resistor network selects different battery thresholds. A

power-up.

The MAX6916 has a crystal-fail-detect circuit and a

data-valid bit. The MAX6916 is available in a 20-pin

QSOP package and is guaranteed to operate over the

-40°C to +85°C extended temperature range.

Applications

Point-of-Sale Equipment

Programmable Logic Controllers

Intelligent Instruments

Fax Machines

Digital Thermostats

Industrial Controls

Features

o Real-Time Clock Counts

Seconds, Minutes, Hours, Date, Month, Day of

Week, and Year with Leap-Year Compensation

Through 2099

o 4MHz SPI-Bus-Compatible Interface at 5V, 2MHz

at 3V, and 3.3V

o SPI Interface Supports Modes 1 and 3 (0, 1 and 1, 1)

o 96 x 8 Bits of RAM for Scratchpad Data Storage

o Uses Standard 32.768kHz, 6pF Load, Watch

Crystal

o Single-Byte or Multiple-Byte (Burst Mode) Data

Transfer for Read or Write of Clock Registers or

RAM

o Battery Monitor and Low-Battery Warning Output

Internal Default for Lithium Backup-Battery

Testing

Pins Available for Other Backup-Battery

Testing Configurations

o Dual Power-Supply Pins for Primary and Backup

Power

o Battery-On Output

o NV RAM Controller

Chip-Enable Gating (Control of CE with Reset

and Power Valid)

o µP Supervisor with Watchdog Input

o Programmable Time/Date Alarm Output

o Data Valid Bit (Loss of All Voltage Alerts User of

Corrupt Data)

o Crystal-Fail Detect

o Small 20-Pin, QSOP Surface-Mount Package

SPI-Compatible RTC with Microprocessor

Supervisor, Alarm, and NV RAM Controller

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

19-3694; Rev 0; 10/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX6916EO30+

-40°C to +85°C

20 QSOP

E20-2

MAX6916EO33+

-40°C to +85°C

20 QSOP

E20-2

MAX6916EO50+

-40°C to +85°C

20 QSOP

E20-2

Pin Configuration and Selector Guide appear at end of data

sheet.

SPI is a trademark of Motorola, Inc.

+Denotes lead-free package.