Document
LTC1329-10/ LTC1329-50/LTC1329A-50 Micropower 8-Bit Current Output D/A Converter
FEATURES
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DESCRIPTION
The LTC ®1329-10/LTC1329-50/LTC1329A-50 are micropower 8-bit current output D/A converters (DACs) with an output range of 0µA to 10µA for the LTC1329-10 and 0µA to 50µA for the LTC1329-50/LTC1329A-50. The DAC current output can be biased from – 15V to 2V or – 15V to 2.5V in 3.3V and 5V systems, respectively. Supply current is only 95µA for the LTC1329-50/LTC1329A-50 and 75µA for LTC1329-10. A shutdown mode drops the supply current to 0.2µA. The LTC1329 can communicate with external circuitry by using one of three interface modes: standard 3-wire serial mode and two pulse modes. Upon power-up, the internal counter resets to 1000 0000B, the DAC output assumes midrange and the chip is configured in 3-wire or pulse mode depending on the signal level at CS. In 3-wire mode, the system MPU can serially transfer 8-bit data to and from the LTC1329. In pulse mode, the upper six bits of the DAC output can be programmed for increment-only (1-wire interface) or increment/decrement (2-wire interface) operation depending on the signal level at DIN. LTC1329 is available in 8-pin SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. Triple Mode is a trademark of Linear Technology Corporation.
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Guaranteed Precision Full-Scale DAC Output Current at 25°C: LTC1329A-50 50µA ±1% LTC1329-10 10µA ±3% LTC1329-50 50µA ±3% Wide Output Voltage DC Compliance: – 15V to 2.5V Wide Supply Range: 2.7V ≤ VCC ≤ 6.5V Supply Current in Shutdown: 0.2µA Low Supply Current: 75µA for LTC1329-10, 95µA for LTC1329-50/LTC1329A-50 Available in 8-Pin SO Triple ModeTM Interface Modes 1. Standard 3-Wire Mode 2. Pulse Mode 1-Wire Interface: Increment-Only 3. Pulse Mode 2-Wire Interface: Increment/Decrement Can Read Back the 8-Bit DAC Value in 3-Wire Mode DAC Powers Up at Midrange DAC Contents Are Retained in Shutdown
U APPLICATIONS
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LCD Contrast Control Backlight Brightness Control Battery Charger Current/Voltage Adjustment Power Supply Voltage Adjustment Trimmer Pot Elimination
TYPICAL APPLICATION
Digitally Controlled LCD Bias Generator
VIN 5V 47Ω VIN SW1 LT ®1173 FB GND SW2 1N5818 ILIM L1* 100µH
1N4148
200k
0.1µF
1 2
IOUT VCC
+
47µF
+
LTC1329-50 4.7µF 10.1k 1N5818 3 4 SHDN CLK GND CS 6 5
+
*GOWANDA GA10-103K OR COILTRONICS CTX100-4
22µF
220k VOUT –22V at 40mA
1329 TA01
U
U
DOUT DIN
8 7 MPU (e.g., 8051)
P1.2 P1.1 P1.0
1
LTC1329-10/ LTC1329-50/LTC1329A-50
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW IOUT 1 VCC 2 SHDN 3 CLK 4 8 DOUT 7 DIN (UP/DN) 6 GND 5 CS
Supply Voltage (VCC) ................................................ 7V Input Voltage (All Inputs)............ – 0.3V to (VCC + 0.3V) Output Voltage IOUT ......................................... – 15V to (VCC + 0.3V) DOUT ....................................... – 0.3V to (VCC + 0.3V) Short-Circuit Duration (All Outputs) ..........