PT7C4302 PERICOM [Pericom Semiconductor Corporation], PT7C4302 Datasheet - Page 4

• Manufacturer Part Number: PT7C4302
• Description: Real-time Clock Module (3-wire Interface)
• Manufacturer: PERICOM [Pericom Semiconductor Corporation]

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Function Description
Overview of Functions
1.
CPU can read or write data including the year (last two digits), month, date, day, hour, minute, and second. Any (two-digit) year
that is a multiple of 4 is treated as a leap year and calculated automatically as such until the year 2099.
2.
Simple 3-wire interface.
3.
Oscillator can be enabled or disable by /EOSC bit. But time count chain does not shut down when the bit is logic 1.
4.
The function is controlled by trickle charge register. Customer can select the charge current by select the number of diode and
resistor value through the register.
For example:
Assume that a system power supply of 5V is applied to VCC2 and a super cap is connected to VCC1. Also assume that the trickle
charger has been enabled with one diode and resistor R1 between VCC2 and VCC1. The maximum current IMAX would,
therefore, be calculated as follows:
As the super cap charges, the voltage drop between VCC1 and VCC2 will decrease and, therefore, the charge current will
decrease.
PT0225(11/05)
Clock function
Interface with CPU
Oscillator enable/disable
Charger function
IMAX = (5.0V - diode drop)/R1 _ (5.0V - 0.7V) / 2kΩ _ 2.2mA
4
Real-time Clock Module (3-wire Interface)
Data Sheet
PT7C4302
Ver: 0