SP9841 datasheet(16/32 Pages) SIPEX

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Pin 10 — V

OUTG — DACG Voltage Output.

Pin 11 — V

OUTH — DACH Voltage Output.

Pin 12 — V

ING/H — DACG and H Reference

Voltage Input.

Pin 13 — LOADH — Load DAC Register Strobe;

active high input that transfers the data bits from the

Serial Input Register into the decoded DAC Register.

Refer to Table 1.

Pin 14 — CLOCK — Serial Clock Input; positive–

edge triggered.

Pin 15 — SDO — Serial Data Output; active totem–

pole output.

Pin 16 — GND — Ground.

Pin 17 — SDI — Serial Data Input.

Pin 18 — V

DD — Positive 5V Power Supply.

Pin 19 — V

INC/D — DACC and D Reference

Voltage Input.

Pin 20 — V

OUTD — DACD Voltage Output.

FEATURES…

The SP9841 and SP9842 include eight separate op

amp–buffered eight–bit DACs. These can be used to

replace up to eight trimpots with eight low–imped-

ance programmable sources. The SP9841 uses eight

separate multiplying reference inputs, while the

SP9842 provides four pair of multiplying inputs. All

of the reference inputs, in either case, are returned to

acommonvoltagereferencelowpin.Theinherent2X

gain from the two–quadrant multiplying reference

inputs to the outputs allows the use of AC or DC

multiplying reference inputs generated from a single,

low supply voltage.

Each DAC has its own data register which holds its

output state. These data registers are updated from an

internalserial-to-parallelshiftregisterwhichisloaded

from a standard 3-wire serial input digital interface.

Twelve data bits make up the data word clocked into

the serial input register. This data word is decoded

such that the first 4 bits determine the address of the

DAC register to be loaded and the last 8 bits are the

data. A serial data output pin at the opposite end of the

serial register allows simple daisy-chaining in mul-

Table 1. Serial Input Decoded Truth Table

LAST

LSB

DATA

ADDRESS

MSB

DAC Output Voltage

VOUT = D/128 (VIN – VREFL) + VREF L

VREFL

1/128 (VIN – VREFL) + VREF L

127/128 (VIN – VREFL) + VREF L

VIN (Preset Value)

129/128 (VIN – VREFL) + VREF L

254/128 (VIN – VREFL) + VREF L

255/128 (VIN – VREFL) + VREF L

LSB

MSB

DAC Updated

FIRST

No Operation

DACA

DACB

DACC

DACD

DACE

DACF

DACG

DACH

No Operation

No operation

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