PT7C4302_15 Datasheet, PDF (1/14 Pages) Pericom Semiconductor Corporation – Real-time Clock Module (3-wire Interface)

PT7C4302
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Real-time Clock Module (3-wire Interface)
Features
 Using external 32.768kHz quartz crystal
 Real-time clock (RTC) counts seconds, minutes
hours, date of the month, month, day of the week,
and year with leap-year compensation valid up to
2099
 31-byte, nonvolatile (NV) RAM for data storage
 Time keeping voltage: 1.5V to 5.5V
 Uses less than 300nA at 2.0V
 Simple 3-wire interface
 Serial I/O for minimum pin count
 Burst mode for reading/writing successive addresses
in clock/RAM
 TTL-compatible (VCC = 5V)
 Optional industrial temperature range: -40°C to
+85°C
 Battery backup
 Trickle charger on chip for rechargeable energy
source backup
Description
The PT7C4302 serial real-time clock is a low-
power clock/calendar with a programmable square-wave
output and 31 bytes of nonvolatile RAM.
Address and data are transferred serially via a 3-
wire bus. The clock/calendar provides seconds, minutes,
hours, day, date, month, and year information. The date
at the end of the month is automatically adjusted for
months with fewer than 31 days, including corrections
for leap year. The clock operates in either the 24-hour or
12-hour format with AM/PM indicator.
Table 1 shows the basic functions of PT7C4302.
More details are shown in section: overview of functions.
Pin Assignment
PT7C4302
1 VCC2
VCC1 8
2 X1
SCLK 7
3 X2
I/O ⁶
4 _GND
RST ⁵
Pin Description
DIP-8
SOIC-8
Pin no. Pin Type
Description
1
VCC
2
P
Primary power. When V_CC2 is greater than V_CC1 + 0.2V, V_CC2 will power the IC. While V_CC2<V_CC1, V_CC1
will power the IC.^*1
2
X1 I Oscillator Circuit Input. Together with X2, 32.768kHz crystal is connected between them.
3
X2 O Oscillator Circuit Output. Together with X1, 32.768kHz crystal is connected between them.
4 GND P Ground.
5
RST
I
Reset. The reset signal must be asserted high during a read or a write. This pin has a 40kΩ internal pull-
down resistor.
6
I/O
I/ Serial Data Input/Output. I/O is the input/output pin for the 3-wire serial interface. The pin has a 40k
O internal pull-down resistor.
7
SCL
K
I
Serial Clock Input. SCLK is used to synchronize data movement on the 3-wire serial interface. The pin
has a 40k internal pull-down resistor.
8
VCC
1
P
Backup power. When V_CC2 is greater than V_CC1 + 0.2V, V_CC2 will power the IC. While V_CC2<V_CC1, V_CC1
will power the IC. ^*1
Note^*1: If V_CC1 connects to battery, the battery voltage V_CC1 has to be lower than V_CC2 - 0.2Vwhen IC is read and written.
2015-11-0004
PT0225-6 11/25/15
1