MAX6917_05 Datasheet, PDF (1/31 Pages) Maxim Integrated Products – I2C-Compatible RTC with Microprocessor Supervisor, Alarm, and NV RAM Controller

19-3702; Rev 1; 10/05
I²C-Compatible RTC with Microprocessor
Supervisor, Alarm, and NV RAM Controller
General Description
The MAX6917 provides all the features of a real-time
clock (RTC) plus a microprocessor (µP) supervisory cir-
cuit, NV RAM controller, and backup-battery monitor
function. In addition, 96 x 8 bits of static RAM are avail-
able for scratchpad storage. The MAX6917 communi-
cates with a µP through an I²C-bus-compatible 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 µP supervisory circuit features an open-drain,
active-low reset available in three different reset thresh-
olds. 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 MAX6917 has a crystal-fail-detect circuit and a
data-valid bit. The MAX6917 is available in a 20-pin
QSOP package and is guaranteed to operate over the
extended (-40°C to +85°C) temperature range.
Applications
Point-of-Sale Equipment
Programmable Logic Controllers
Intelligent Instruments
Fax Machines
Digital Thermostats
Industrial Control
Pin Configuration and Selector Guide appear at end of data
sheet.
Features
♦ Real-Time Clock Counts
Seconds, Minutes, Hours, Date,
Month, Day of Week, and Year
with Leap-Year Compensation Through 2099
♦ Fast (400kHz) I²C-Bus-Compatible Interface
♦ 96 x 8 Bits of RAM for Scratchpad Data Storage
♦ Uses Standard 32.768kHz, 6pF Load, Watch
Crystal
♦ Single-Byte or Multiple-Byte (Burst Mode) Data
Transfer for Read or Write of Clock Registers or
RAM
♦ Battery Monitor and Low-Battery Warning Output
Internal Default for Lithium Backup-Battery
Testing
Pins Available for Other Backup-Battery
Testing Configurations
♦ Dual Power-Supply Pins for Primary and Backup
Power
♦ Battery-On Output
♦ NV RAM Controller
Chip-Enable Gating (Control of CE with Reset
and Power Valid)
V_OUT for SRAM Power
♦ Microprocessor Supervisor with Watchdog Input
♦ Programmable Time/Date Alarm Output
♦ Data Valid Bit (Loss of All Voltage Alerts User of
Corrupt Data)
♦ Crystal-Fail Detect
♦ Reference Output Frequencies—1Hz and
32.768kHz
♦ Small, 20-Pin, QSOP Surface-Mount Package
Ordering Information
PART
TEMP RANGE
MAX6917EO30+ -40°C to +85°C
MAX6917EO33+ -40°C to +85°C
MAX6917EO50+ -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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