5

LTC1657

WR (Pin 1): Write Input (Active Low). Used with CSMSB

and/or CSLSB to control the input registers. While WR and

CSMSB and/or CSLSB are held low, data writes into the

input register.

CSLSB (Pin 2): Chip Select Least Significant Byte (Active

Low). Used with WR to control the LSB 8-bit input regis-

ters. While WR and CSLSB are held low, the LSB byte

writes into the LSB input register. Can be connected to

CSMSB for simultaneous loading of both sets of input

latches on a 16-bit bus.

CSMSB (Pin 3): Chip Select Most Significant Byte (Active

Low). Used with WR to control the MSB 8-bit input

registers. While WR and CSMSB are held low, the MSB

byte writes into the MSB input register. Can be connected

to CSLSB for simultaneous loading of both sets of input

latches on a 16-bit bus.

D0 to D7 (Pins 4 to 11): Input data for the Least Significant

Byte. Written into LSB input register when WR = 0 and

CSLSB = 0.

D8 to D15 (Pins 12 to 19): Input data for the Most Signifi-

cant Byte. Written into MSB input register when WR = 0

and CSMSB = 0.

GND (Pin 20): Ground.

REFLO (Pin 21): Lower input terminal of the DAC’s inter-

nal resistor ladder. Typically connected to Analog Ground.

the output buffer to this end of the ladder. Can be used to

offset the zero scale above ground.

REFHI (Pin 22): Upper input terminal of the DAC’s internal

resistor ladder. Typically connected to REFOUT. An input

output buffer to 1LSB below this voltage.

REFOUT (Pin 23): Output of the internal 2.048V reference.

Typically connected to REFHI to drive internal DAC resistor

ladder.

5.5V. Requires a 0.1

µF bypass capacitor to ground.

X1/X2 (Pin 26): Gain Setting Resistor Pin. Connect to GND

to ensure stability of the output buffer when driving

capacitive loads.

CLR (Pin 27): Clear Input (Asynchronous Active Low). A

low on this pin asynchronously resets all input and DAC

registers to 0s.

LDAC (Pin 28): Load DAC (Asynchronous Active Low).

Used to asynchronously transfer the contents of the input

registers to the DAC register which updates the output

voltage. If held low, the DAC register loads data from the