ST3243B ST3243C

Description

Doc ID 7539 Rev 10

3/17

1

Description

The ST3243B / ST3243C devices consist of 3 drivers, 5 receivers and a dual charge-pump

circuit. The devices meet the requirements of EIA/TIA and V.28/V.24 communication

standards providing high data rate capability.

The receiver R2 is always active to implement a wake-up feature for serial port.

The ST3243B / ST3243C have a proprietary low-dropout transmitter output stage enabling

true RS-232 performance from a 3.0 V to 5.5 V supply with a dual charge pump. The

devices are guaranteed to run at data rates of 250 kbps while maintaining RS-232 output

levels.

The auto-power-down feature functions when FORCEON is low and FORCEOFF is high.

During this mode of operation, if the device does not sense a valid RS-232 signal, the driver

outputs are disabled. If FORCEOFF is set low, both drivers and receivers (expert R2B) are

shut off, and supply current is reduced to 1 mA. Disconnecting the serial port or turning off

the peripheral drives causes the auto-power-down condition to occur.

Auto-power-down can be disabled when FORCEON and FORCEOFF are high, and should

be done when driving a serial mouse. With auto-power-down enabled, the device is

activated automatically when a valid signal is applied to any receiver input.

Typical application are in notebook, sub-notebook, palmtop computers, battery-powered

equipment, hand-held equipment, peripherals and printers.