MCP79400T-I/ST Microchip Technology, MCP79400T-I/ST Datasheet - Page 11

• Manufacturer Part Number: MCP79400T-I/ST
• Description: Real Time Clock I2C GP RTCC 64B SRAM ID
• Manufacturer: Microchip Technology
• Series: -r
• Type: Clock/Calendarr

Specifications of MCP79400T-I/ST

• Features: Alarm, Leap Year, SRAM
• Memory Size: 64B
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C
• Voltage - Supply: 1.8 V ~ 5.5 V
• Voltage - Supply, Battery: 1.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TABLE 4-1:
4.1.1
0x00h – Contains the BCD seconds and 10 seconds.
The range is 00 to 59. Bit 7 in this register is used to
start or stop the on-board crystal oscillator. Setting this
bit to a ‘1’ starts the oscillator and clearing this bit to a
‘0’ stops the on-board oscillator.
0x01h – Contains the BCD minutes and 10 minutes.
The range is 00 to 59.
0x02h – Contains the BCD hour in bits 3:0. Bits 5:4
contain either the 10 hour in BCD for 24-hour format or
the AM/PM indicator and the 10-hour bit for 12-hour
format. Bit 6 determines the hour format. Setting this
bit to ‘0’ enables 24-hour format, setting this bit to ‘1’
enables 12-hour format.
0x03h – Contains the BCD day. The range is 1-7.
Additional bits are also used for configuration and
status.
• Bit 3 is the VBATEN bit. If this bit is set, the
• Bit 4 is the V
• Bit 5 is the OSCON bit. This is set and cleared by
0x04h – Contains the BCD date and 10 date. The
range is 01-31.
0x05h – Contains the BCD month. Bit 4 contains the
10 month. Bit 5 is the Leap Year bit, which is set during
a leap year and is read-only.
0x06h – Contains the BCD year and 10 year. The
Range is 00-99.
0x07h – Is the Control register.
 2011 Microchip Technology Inc.
1Ch
1Dh
1Eh
1Fh
Address
internal circuitry is connected to the V
when V
disconnected and the only current drain on the
external battery is the V
when the V
the Oscillator and the RTCC registers. This bit is
cleared by software. Clearing this bit will also
clear all the time-stamp registers.
hardware. If this bit is set, the oscillator is running,
if cleared, the oscillator is not running. This bit
does not indicate that the oscillator is running at
the correct frequency. The RTCC will wait 32
oscillator cycles before the bit is set. The RTCC
will wait roughly 32 clock cycles to clear this bit.
CC
RTCC REGISTER ADDRESSES
Bit 7
fails. If this bit is ‘0’ then the V
CC
BAT
fails and the V
RTCC MEMORY MAP (CONTINUED)
bit. This bit is set by hardware
10 Minutes
12/24
Day
Bit 6
BAT
pin leakage.
BAT
10 Hour
AM/PM
Bit 5
is used to power
10 Date
BAT
10 Hours
10 Month
BAT
Bit 4
pin
pin is
Bit 3
Bit 2
Minutes
Month
Hour
Date
• Bit 7 is the OUT bit. This sets the logic level on the
• Bit 6 is the SQWE bit. Setting this bit enables the
• Bits 5:4 determine which alarms are active.
• Bit 3 is the EXTOSC enable bit. Setting this bit will
• Bit 2:0 sets the internal divider for the 32.768 kHz
0x08h is the Calibration register. This is an 8-bit
register that is used to add or subtract clocks from the
RTCC counter every minute. The MSB is the sign bit
and indicates if the count should be added or
subtracted. The remaining 7 bits, with each bit adding
or subtracting 2 clocks, give the user the ability to add
or subtract up to 254 clocks per minute.
0x09h is the unlock sequence address. To unlock write
access to the unique ID area in the EEPROM, a
sequence must be written to this address in separate
commands.
Section 4.2.1 “Unlock
0x0Ah-0x0fh and 0x11-0x16h are the Alarm 0 and
Alarm 1 registers. The bits are the same as the RTCC
bits with the following differences:
Locations 0x10h and 0x17h are reserved and should
not be used to allow for future device compatibility.
0x0Dh/0x14h has additional bits for alarm configu-
ration.
MFP when not using this as a square wave out-
put.
divided output from the crystal oscillator.
- 00 – No Alarms are active
- 01 – Alarm 0 is active
- 10 – Alarm 1 is active
- 11 – Both Alarms are active
allow an external 32.768 kHz signal to drive the
RTCC registers eliminating the need for an
external crystal.
oscillator to be driven to the MFP. The duty cycle is
50%. The output is responsive to the Calibration
register. The following frequencies are available:
- 000 – 1 Hz
- 001 – 4.096 kHz
- 010 – 8.192 kHz
- 011 – 32.768 kHz
- 1xx enables the Cal output function. Cal
Note:
Bit 1
output appears on MFP if SQWE is set (64
Hz Nominal).
Bit 0
The RTCC counters will continue to
increment during the calibration.
The
Function
process
Sequence”.
MCP7940X
is
fully
Range
DS25009A-page 11
detailed
Reset
State
00h
00h
00h
00h
in