DAC-LTC144X

A small KiCad breakout board and an Arduino driver for the Linear Technology LTC1446 / LTC1446L — a dual 12-bit rail-to-rail DAC with an internal reference and a 3-wire SPI interface in an 8-pin package.

The part

	LTC1446	LTC1446L
Supply	4.5V – 5.5V	2.7V – 5.5V
Full-scale output	4.095V (1mV per LSB)	2.5V
Resolution	12 bits, 2 channels	12 bits, 2 channels
Interface	3-wire SPI, 24-bit word	3-wire SPI, 24-bit word
Settling time	14µs to ±0.5 LSB	14µs to ±0.5 LSB

Both channels are written in a single 24-bit transfer: the first 12 bits set DAC A, the second 12 set DAC B. Data is latched on the rising edge of CLK (SPI mode 0, MSB first), and the outputs update when CS/LD returns high. The DAC has a power-on reset that clears both channels to 0V.

The board

Two-layer, 18 × 22 mm, through-hole headers, designed in KiCad 6.

Ref	Value	Purpose
U1	LTC1446	Dual 12-bit DAC, SO-8
R1	10k	Pull-up on CS/LD to VCC
C1	0.1µF	VCC bypass
J1	1x5 header	Control in — CLK, D_IN, CS, VCC, GND
J2	1x2 header	Analog out — Vout A, Vout B

Open LTC1446-BRD.kicad_pro in KiCad 6 or newer.

Wiring

J1 pin	Signal	Arduino (Uno)
1	CLK	13 (SCK)
2	D_IN	11 (MOSI)
3	CS	10 (or any digital pin)
4	VCC	5V
5	GND	GND

The DAC's D_OUT pin is brought to U1 only; it exists so multiple LTC1446s can be daisy-chained, and is left unconnected on this board.

The Arduino library

Copy this repository into your Arduino libraries/ folder, or clone it there:

git clone https://github.com/stephf0716/DAC-LTC144X ~/Documents/Arduino/libraries/LTC1446

#include <LTC1446.h>

LTC1446 dac(10);  // CS/LD wired to pin 10

void setup() {
  dac.begin();
  dac.setVoltage(2048, 0);  // A to mid-scale (~2.048V), B to 0V
}

void loop() {}

API

• LTC1446(uint8_t csPin) — construct with the pin wired to CS/LD.
• begin() — configures the CS pin and starts SPI.
• setVoltage(uint16_t voutA, uint16_t voutB) — writes both channels in one transfer. Codes run 0 to LTC1446_MAX_CODE (4095) and are clamped, since a value wider than 12 bits would overflow into the other channel.

See examples/BasicSweep for a full sketch that ramps both channels.

Repository layout

src/                    Arduino library sources
examples/BasicSweep/    example sketch
datasheets/             LTC1446 datasheet
LTC1446-BRD.*           KiCad 6 project, schematic, and PCB layout

License

MIT — see LICENSE. The bundled datasheet is the property of Linear Technology / Analog Devices and is included for convenience only.