MAX14842 datasheet(11/13 Pages) MAXIM

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6-Channel, Digital Ground-Level Translator

Detailed Description

The MAX14842 provides both ground-level transla-

tion and logic-level shifting needed in systems where

there is a difference in ground references of up to 72V.

The device is powered by two supply voltages, VDDA

and VDDB, which independently set the logic levels on

either side of the device. VDDA and VDDB are sepa-

rately referenced to GNDA and GNDB, respectively. The

MAX14842 supports data rates of up to 30Mbps on each

of the four unidirectional channels and 2Mbps on the two

bidirectional channels.

Ground Translation/Level Shifting

For proper operation, ensure that 0V P (VGNDB - VGNDA)

72V. Note that GNDB must be greater than or equal to

GNDA.

Also ensure that 3.0V P (VDDA - VGNDA) P 5.5V and

3.0V P (VDDB - VGNDB) P 5.5V. (VDDA - VGNDA) can be

greater than or less than (VDDB - VGNDB), as long as

each is within the normal operating range.

Unidirectional Channels

The device features four unidirectional channels that can

each operate independently with a guaranteed data rate

of up to 30Mbps. The output driver of each unidirectional

channel is push-pull, eliminating the need for pullup

resistors. The drivers are also able to drive both TTL and

CMOS logic inputs.

Bidirectional Channels

The device features two bidirectional translation chan-

nels that have open-drain outputs. The bidirectional

channels do not require a direction input. A logic-low on

one side causes the corresponding pin on the other side

to be pulled low while avoiding data latching within the

translator. To prevent latching of the bidirectional chan-

nels, the input logic-low threshold (VIT) of I/OA1 and I/

OA2 is at least 50mV lower than the output logic-low volt-

ages (VOL) of I/OA1 and I/OA2. This prevents an output

logic-low on side A from being accepted as an input low

and subsequently transmitted to side B and vice versa.

The I/OA1, I/OA2, I/OB1, and I/OB2 pins have open-drain

outputs, requiring pullup resistors to their respective sup-

plies for logic-high outputs. The output low voltages are

guaranteed for sink currents of up to 30mA for side B and

10mA for side A (see the Electrical Characteristics table).

The bidirectional channels of the device support I2C

clock stretching.

Separate Ground References

The device is designed to translate logic signals to and

from domains with isolated and offset ground references.

Startup and Undervoltage Lockout

The VDDA and VDDB supplies are both internally moni-

tored for undervoltage conditions. Undervoltage events

can occur during power-up, power-down, or during

normal operation due to a slump in the supplies. When

an undervoltage event occurs on either of the supplies,

all outputs on both sides are automatically controlled,

regardless of the status of the inputs. The bidirectional

outputs become high impedance and are pulled high by

the external pullup resistor on the open-drain output. The

unidirectional outputs are pulled high internally to the

voltage of the VDDA or VDDB supply during undervoltage

conditions.

Functional Diagram

MAX14842

INA1

VDDA

VDDB

GNDA

GNDB

GROUND

REFERENCE

SHIFTER

INA2

OUTA1

OUTA2

I/OA1

I/OA2

OUTB1

OUTB2

INB1

INB2

I/OB1

I/OB2

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