8
32” TFT TV Service Manual
06/03/2006
12.4. ST24LC21
12.4.1. Description
The ST24LC21 is a 1K bit electrically erasable programmable memory (EEPROM), organized by 8 bits.
This device can operate in two modes: Transmit Only mode and I
2
C bidirectional mode. When powered,
the device is in Transmit Only mode with EEPROM data clocked out from the rising edge of the signal
applied on VCLK. The device will switch to the I
2
C bidirectional mode upon the falling edge of the signal
applied on SCL pin. The ST24LC21 can not switch from the I
2
C bidirectional mode to the Transmit Only
mode (except when the power supply is removed). The device operates with a power supply value as low
as 2.5V. Both Plastic Dual-in-Line and Plastic Small Outline packages are available.
12.4.2. Features
• 1 million Erase/Write cycles
• 40 years data retention
• 2.5V to 5.5V single supply voltage
• 400k Hz compatibility over the full range of supply voltage
• Two wire serial interface I
2
C bus compatible
• Page Write (Up To 8 Bytes)
• Byte, random and sequential read modes
• Self timed programming cycle
• Automatic address incrementing
• Enhanced ESD/Latch up
• Performances
12.4.3. Pin
connections
DIP Pin connections
CO Pin connections
NC: Not connected
Signal names
SDA Serial
data
Address Input/Output
SCL
Serial Clock (I
2
C mode)
V
cc
Supply
voltage
V
ss
Ground
VCLK
Clock transmit only mode
