LTC1655IS8 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC1655IS8

16-Bit Rail-to-Rail Micropower DACs in SO-8 Package

Linear Technology 

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LTC1655/LTC1655L

TYPICAL APPLICATIONS

This circuit shows a digitally programmable current source

from an external voltage source using an external op amp,

an LT1218 and an NPN transistor (2N3440). Any digital

word from 0 to 65535 is loaded into the LTC1655 and its

output correspondingly swings from 0V to 4.096V. This

voltage will be forced across the resistor RA. If RA is

chosen to be 412Ω, the output current will range from

0mA at zero scale to 10mA at full scale. The minimum

voltage for VS is determined by the load resistor RL and

Q1’s VCESAT voltage. With a load resistor of 50Ω, the

voltage source can be 5V.

Digitally Programmable Current Source

5V

5V < VS < 100V

8

0.1µF

FOR RL ≤ 50Ω

µP

1

VCC

CLK

2

DIN

LTC1655

3

CS/LD

GND

VOUT 7

3+ 7

LT1218 6

2–

RL

IOUT

=

(DIN)(4.096)

(65536)(RA)

Q1

≈ 0mA TO 10mA

2N3440

4

5

RA

412Ω

1%

1655/55L TA04

13

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