6

Memory ICs

BA6129AF / BA6162 / BA6162F

These ICs have two distinct functions, a logic output function and a power supply switching function.

The logic output circuit consists of the following:

(1) Reset output (NPN Tr open collector)

(2) CS output

(PNP Tr open collector + pull-down resistor)

(3) CSB output

(NPN Tr open collector + pull-up resistor)

The power supply switching circuit consists of a PNP

power transistor and an SBD (Schottky barrier diode).

ing circuit. When the PNP power transistor is turned on

and off, the IC power is switched from the normal

power supply to the battery backup power supply, and

vice versa.

The power supply voltage detection circuit consists of a

resistance. When the power supply voltage drops

the CS signal (CS-Low, CSB-High) are output by the

logic output function, and the SRAM (or other memory

device) is switched to backup mode.

rises), the SBD develops a forward bias because the

PNP power transistor is off. The power supply output

process is reversed.

Fig. 2 Timing chart

RESET

CSB

CS

5V

OV

(BA6129AF) (BA6162 / F)

[

GND]

[

GND]

[

GND]

OV

[

[

[