Toshiba 29VH27E, Service Manual

Page: 68 / 171

7
Signal Names
A0-A18 Address Inputs
Q0-Q7 Data Outputs
E Chip Enable
G Output Enable
V
pp
Program Supply
V
cc
Supply Voltage
V
ss
Ground
14.3.24LC32A
14.3.1.Description
The Microchip Technology Inc. 24LC32A is a 4K x 8 (32K bit) Serial Electrically Erasable PROM
capable of operation across a broad voltage range (2.5V to 6.0V). It has been developed for advanced,
low power applications such as personal communications or data acquisition. The 24LC32A also has a
page-write capability of up to 32 bytes of data. The 24LC32A is capable of both random and sequential
reads up to the 32K boundary. Functional address lines allow up to eight 24LC32A devices on the
same bus, for up to 256K bits address space. Advanced CMOS technology and broad voltage range
make this device ideal for low-power/ low-voltage, nonvolatile code and data applications. The
24LC32A is available in the standard 8-pin plastic DIP and both 150 mil and 200 mil SOIC packaging.
14.3.2.Features
• Single supply with operation down to 2.5V
• Maximum write current 3 mA at 6.0V
• Standby current 1 mA max at 2.5V
• 2-wire serial interface bus, I 2 CÔ compatible
• 100 kHz (2.5V) and 400 kHz (5V) compatibility
• Self-timed ERASE and WRITE cycles
• Power on/off data protection circuitry
• Hardware write protect
• 1,000,000 Erase/Write cycles guaranteed
• 32 byte page or byte write modes available
• Schmitt trigger filtered inputs for noise suppression
• Output slope control to eliminate ground bounce
• 2 ms typical write cycle time, byte or page
• Up to eight devices may be connected to the same bus for up to 256K bits total memory
• Electrostatic discharge protection > 4000V
• Data retention > 200 years
• 8-pin PDIP and SOIC packages
• Temperature ranges
• Commercial (C): 0°C to +75°C
• Industrial (I): -40°C to +85°C
14.3.3.Pin Descriptions
A0, A1, A2 Chip Address Inputs
The A0..A2 inputs are used by the 24LC32A for multiple device operation and conform to the 2-wire bus
standard. The levels applied to these pins define the address block occupied by the device in the
address map. A particular device is selected by transmitting the corresponding bits (A2, A1, A0) in the
control byte.
SDA Serial Address/Data Input/Output
This is a Bi -directional pin used to transfer addresses and data into and data out of the device. It is an
open drain terminal, therefore the SDA bus requires a pull up resistor to V
CC
(typical 10 kO for 100 kHz,
2 kO for 400 kHz) For normal data transfer SDA is allowed to change only during SCL low. Changes
during SCL HIGH are reserved for indicating the START and STOP conditions.
SCL Serial Clock
This input is used to synchronize the data transfer from and to the device.