MAX6916_05 Datasheet, PDF (1/28 Pages) Maxim Integrated Products – SPI-Compatible RTC with Microprocessor Supervisor, Alarm, and NV RAM Controller

19-3694; Rev 0; 10/05
SPI-Compatible RTC with Microprocessor
Supervisor, Alarm, and NV RAM Controller
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
freshness seal prevents battery drain until the first V_CC
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
Pin Configuration and Selector Guide appear at end of data
sheet.
SPI is a trademark of Motorola, Inc.
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)
V_OUT for SRAM Power
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
Ordering Information
PART
TEMP RANGE
MAX6916EO30+
MAX6916EO33+
MAX6916EO50+
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
+Denotes lead-free package.
PIN-
PACKAGE
20 QSOP
20 QSOP
20 QSOP
PKG
CODE
E20-2
E20-2
E20-2
________________________________________________________________ Maxim Integrated Products 1
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1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.