MAX6909 Datasheet, PDF (1/33 Pages) Maxim Integrated Products – I2C-Compatible Real-Time Clocks with uP Supervisor and NV RAM Controller

19-3322; Rev 0; 8/04
I²C-Compatible Real-Time Clocks with µP
Supervisor and NV RAM Controller
General Description
The MAX6909/MAX6910 are I²C-compatible real-time
clocks (RTCs) with a microprocessor supervisor, option-
al trickle charger (MAX6910 only), backup power
source, and NV RAM controller. The MAX6909/
MAX6910 provide alarm outputs to indicate a crystal fail-
ure, a switchover to battery power, and time and date
indication. The NV RAM is 31 bytes of static RAM that
are available for scratchpad storage. The MAX6909/
MAX6910 are controlled through a 2-wire serial bus.
The real-time clock/calendar provides seconds, min-
utes, hours, day, date, month, and year information.
The date is automatically adjusted for months with
fewer than 31 days, including corrections for leap year
up to the year 2100. The clock operates in either the
24-hour or 12-hour format with an AM/PM indicator. A
time/date-programmable ALARM output completes the
features list for the real-time clock section of the
MAX6909/MAX6910. The alarm function can also be
used in a polled mode by periodically reading the
alarm out status bit in the minutes register. A crystal fail
output, CX FAIL, indicates loss of accurate timekeeping
due to crystal problems.
A built-in µP supervisor with an open-drain reset
ensures the µP powers up in a known state. A reset
threshold is available for 3V or 3.3V supplies. The piezo
transducer output, PZT, is register selectable for one of
four frequencies, can be turned on and off through a
register bit, or selected to go on when the ALM, alarm
output, goes active.
The MAX6909/MAX6910 are available in a 20-pin QSOP
package and operate over the -40°C to +85°C temper-
ature range.
Applications
Point-of-Sale Equipment
Programmable Logic Controller
Handheld Instruments
Medical Instrumentation
Features
♦ RTC Counts Seconds, Minutes, Hours, Date of the
Month, Month, Day of the Week, and Year, with
Leap Year Compensation Valid Up to 2100
♦ 31 Bytes of RAM for Scratchpad Data Storage
♦ Uses Standard 32.768kHz, 6pF Load, Watch
Crystal
♦ Programmable Time/Date, Open-Drain ALARM
Output (Status Can also Be Polled)
♦ Chip Enable Gating (Control of CE with Reset and
Power Valid)
♦ OUT Pin for SRAM Power
♦ µP Reset Output
♦ Watchdog Input
♦ Manual Reset Input with Push-Button Switch
Debounce
♦ Independent Power-Fail and Reset Comparators
♦ 400kHz 2-Wire Interface
♦ Single-Byte or Multiple-Byte (Burst Mode) Data
Transfer for Read or Write of Clock Registers or
RAM
♦ Bus Timeout to Prevent Lockup of Malfunctioning
Bus Interface
♦ Dual Power-Supply Pins for Primary and Backup
Power
♦ Programmable Trickle Charger (MAX6910)
♦ Uses Less than 1µA Timekeeping Current at 3.0V
♦ Operating Voltages of 3V and 3.3V
Ordering Information
PART
MAX6909EO30
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
20 QSOP
MAX6909EO33
MAX6910EO30
MAX6910EO33
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
20 QSOP
20 QSOP
20 QSOP
Pin Configuration/Selector Guide/Typical Operating Circuit
appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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