Motorola P8190 Service Manual download pdf (Page 138)

R1201

TDMA StarTAC

P8190: Memory

A40

Description

A serial EEPROM(U1003) of 256K bytes is used for storage of the NAM information, authentication keys, phasing data, ESN, and memory. The EEPROM serial inter-

face to the microcontroller is a standard SPI-compatible interface.

U1300 is a 64K x 16 low voltage, low power SRAM. U1300 uses a parallel interface bus.

U1200 is a 512K x 8 flash EPROM. U1200 uses a parallel interface bus.

The WP* line is used during EPROM flash conditions. When the EPROM is not being flashed, WP* is at a low state. This condition will switch Q1722 off, thus, allow-

ing the gate of Q1721 to be pulled high. A high state at the gate of Q1721 will switch Q1721 off, thus, not allowing WP* from U1200 to be pulled high by B+.

During flashing conditions, WP* is pulled high. This condition will switch Q1722 on, allowing the voltage at the gate of Q1721 to drop. A lower voltage at the gate of

Q1721 will switch the transistor on. This condition will allow WP* from U1200 to be pulled high by B+.

B+

WP*

Q1721

Q1722

U1200

WP*