LTC1658CS8#PBF Linear Technology, LTC1658CS8#PBF Datasheet - Page 9

• Manufacturer Part Number: LTC1658CS8#PBF
• Description: IC D/A CONV 14BIT R-R 8-SOIC
• Manufacturer: Linear Technology

Specifications of LTC1658CS8#PBF

• Settling Time: 12µs
• Number Of Bits: 14
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 3mW
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Number Of Channels: 1
• Resolution: 14b
• Interface Type: Serial (3-Wire, SPI, Microwire)
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Supply Requirement: Single
• Output Type: Voltage
• Integral Nonlinearity Error: ±8LSB
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

This circuit shows how to use an LTC1658 to make an
optoisolated digitally controlled 4mA to 20mA process
controller. The controller circuitry, including the
optoisolation, is powered by the loop voltage that can have
a wide range of 3.8V to 30V. The 3.3V output of the
LT1121-3.3 is used for the 4mA offset current and V
TYPICAL APPLICATIO S
CS/LD
CLK
D
IN
IN
LT
®
1121-3.3
OUT
ISOLATED
OPTOISOLATORS
INPUTS
500
OPTO-
FROM
+
1 F
U
4N28
CLK
D
CS/LD
An Optoisolated 4mA to 20mA Process Controller
IN
V
3.3V
CC
LTC1658
3.6k
REF
CLK
D
CS/LD
IN
V
OUT
OUT
is
60.4k
237k
1%
1%
used for the digitally controlled 0mA to 16mA current. R
is a sense resistor and the op amp modulates the transis-
tor Q1 to provide the 4mA to 20mA current through this
resistor. The potentiometers allow for offset and full-scale
adjustment. The control circuitry dissipates well under the
4mA budget at zero-scale.
20k
5k
3.01k
1%
1658 TA04
+
–
LT1077
1k
Q1
2N3440
R
10
S
V
3.8V TO 30V
I
OUT
LOOP
LTC1658
9
S