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LTC1348CG-PBF

3.3V/5V Low Power RS232 3-Driver/5-Receiver Transceiver

Linear Technology 

LTC1348

PI FU CTIO S

VCC: 3V to 5.5V Input Supply Pin. This pin should be

decoupled with a 0.1µF ceramic capacitor.

GND: Ground Pin.

RXEN: TTL/CMOS Compatible Enable Pin. Refer to Table

1 for its functional description.

DREN: TTL/CMOS Compatible Enable Pin. Refer to Table

1 for its functional description.

V+: Positive Supply Output (RS232 Drivers). This pin

requires an external capacitor C = 0.1µF for charge stor-

age. The capacitor may be tied to ground or VCC. With

multiple devices, the V+ and V – pins may be paralleled into

common capacitors. For large numbers of devices, in-

creasing the size of the shared common storage capaci-

tors is recommended to reduce ripple.

V–: Negative Supply Output (RS232 Drivers). This pin

requires an external capacitor C = 0.1µF for charge

storage.

C1+, C1–, C2+, C2–, C3+, C3–: Commutating Capacitor

Inputs. These pins require three external capacitors C =

0.1µF: one from C1+ to C1–, another from C2+ to C2– and

another from C3+ to C3–. To maintain charge pump

efficiency, the capacitor’s effective series resistance should

be less than 1Ω. Ceramic capacitors are recommended.

DR IN: RS232 Driver Input Pins. Inputs are TTL/CMOS

compatible. The inputs of unused drivers can be left

unconnected since 300k input pull-up resistors to VCC are

included on chip. To minimize power consumption, the

internal driver pull-up resistors are disconnected from VCC

in the Shutdown or Receiver Alive mode.

DR OUT: Driver Outputs at RS232 Voltage Levels. Outputs

are in a high impedance state when in the Shutdown,

Receiver Alive mode or VCC = 0V. The driver outputs are

protected against ESD to ±10kV for human body model

discharges.

RX IN: Receiver Inputs. These pins can be forced to ±25V

without damage. The receiver inputs are protected against

ESD to ±10kV for human body model discharges. Each

receiver provides 0.4V of hysteresis for noise immunity. In

Receiver Alive mode all receivers have no hysteresis.

RX OUT: Receiver Outputs with TTL/CMOS Voltage Lev-

els. Outputs are in a high impedance state when in the

Shutdown or Receiver Disable mode to allow data line

sharing.

Table 1. Functional Description

MODE

RX ENABLE DR ENABLE

Shutdown

0

0

Receiver

0

1

Disable

Receiver

1

0

Alive

Normal

1

1

DRIVERS

All Drivers Shutdown.

All Driver Outputs Assume High Impedance.

All Driver Pull-Up Resistors Disconnect

From VCC.

All Drivers Alive.

All Drivers Shutdown.

All Driver Outputs in Three-State.

All Driver Pull-Up Resistors Disconnect

From VCC.

All Drivers Alive.

RECEIVERS

All Receivers Shutdown.

All Receiver Outputs Assume High Impedance.

ICC TYP

0.2µA

All Receiver Outputs in Three-State.

All Receivers Alive.

600µA at

3.3V,

800µA at

5V

15µA

All Receivers Alive.

600µA at

3.3V,

800µA at

5V

5

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