Service manual

Model no.:CT-21CBS5CPH.doc
version 1.0
40
3) Pin Configuration
4) Pin Description
SERIAL CLOCK (SCL): The SCL input is used to positive edge clock data into
each EEPROM device and negative edge clock data out of each device.
SERIAL DATA (SDA): The SDA pin is bi-directional for serial data transfer. This
pin is open-drain driven and may be wire-ORed with any number of other
open-drain or open-collector devices.
DEVICE/PAGE ADDRESSES (A2, A1, A0): The A2, A1 and A0 pins are device
address inputs that are hard wired for the AT24C01A and the AT24C02. As many
as eight 1K/2K devices may be addressed on a single bus system (device
addressing is discussed in detail under the Device Addressing section).
The AT24C04 uses the A2 and A1 inputs for hard wire addressing and a total of
four 4K devices may be addressed on a single bus system. The A0 pin is a no
connect.
The AT24C08 only uses the A2 input for hardwire addressing and a total of two
8K devices may be addressed on a single bus system. The A0 and A1 pins are no
connects.
The AT24C16 does not use the device address pins, which limits the number of
devices on a single bus to one. The A0, A1 and A2 pins are no connects.
WRITE PROTECT (WP): The AT24C01A/02/04/16 has a Write Protect pin that provides
hardware data protection.
The Write Protect pin allows normal read/write operations when connected to
ground (GND). When the Write Protect pin is connected to Vcc, the write
protection feature is enabled and operates as shown in table 14.