LT1330

6

1330fb

PIN FUNCTIONS

with a 0.1μF ceramic capacitor close to the package pin.

Insufficient supply bypassing can result in low output drive

levels and erratic charge pump operation.

capacitor. This pin may also be connected to 5V.

GND: Ground Pin.

ON/OFF: TTL/CMOS Compatible Operating Mode Control.

A logic low puts the device in the low power shutdown

mode. All three drivers and four receivers (RX1, RX2,

RX3, and RX4) assume a high impedance output state

in shutdown. Only receiver RX5 remains active while the

transceiver is in shutdown. The transceiver consumes

only 60μA of supply current while in shutdown. A logic

high fully enables the transceiver.

DRIVER DISABLE: This pin provides an alternate control

for the charge pump and RS232 drivers. A logic high

on this pin shuts down the charge pump and places all

driver outputs in a high impedance state. All five receivers

remain active under these conditions. Floating the driver

disable pin or driving it to a logic low level fully enables the

transceiver. A logic low on the ON/OFF pin supersedes the

state of the DRIVER DISABLE pin. Supply current drops

to 3mA when in driver disable mode.

requires an external charge storage capacitor, C ≥ 1.0μF,

tied to ground or 5V. Larger value capacitors may be used

requires an external charge storage capacitor, C ≥ 0.1μF.

See the Applications Information section for guidance in

Commutating Capacitor Inputs

effective series resistance should be less than 2Ω. For

C ≥ 1μF, low ESR tantalum capacitors work well, although

ceramic capacitors may be used with a minimal reduction

in charge pump compliance.

DRIVER IN: RS232 Driver Input Pins. These inputs are

TTL/CMOS compatible. Unused inputs should be connected

DRIVER OUT: Driver Outputs at RS232 Voltage Levels.

Driver output swing meets RS232 levels for loads up to

3k. Slew rates are controlled for lightly loaded lines. Output

current capability is sufficient for load conditions up to

2500pF. Outputs are in a high impedance state when in

pin is active. Outputs are fully short-circuit protected from

damage the device if the overdrive is moderately current

limited. Short circuits on one output can load the power

supply generator and may disrupt the signal levels of the

other outputs. The driver outputs are protected against

ESD to ±10kV for human body model discharges.

RX IN: Receiver Inputs. These pins accept RS232 level

signals (±30V) into a protected 5k terminating resistor.

The receiver inputs are protected against ESD to ±10kV

for human body model discharges. Each receiver provides

0.4V of hysteresis for noise immunity. Open receiver inputs

assume a logic low state.

RX OUT: Receiver Outputs with TTL/CMOS Voltage Levels.

Outputs are in a high impedance state when in shutdown

mode to allow data line sharing. Outputs, including LOW-Q

with the power on, off, or in shutdown mode.

LOW Q-CURRENT RX IN: Low Power Receiver Input.

This special receiver remains active when the part is in

shutdown mode, consuming typically 60μA. This receiver

has the same 5k input impedance and ±10kV ESD protection

characteristics as the other receivers.

LOW Q-CURRENT RX OUT: Low Power Receiver Output.

This pin produces the same TTL/CMOS output voltage

levels as receivers RX1, RX2, RX3, and RX4 with slightly

decreased speed and short-circuit current. Data rates to

120kbaud are supported by this receiver.