LTC1428-50 Micropower 8-Bit Current Sink Output D/A Converter FEATURES DESCRIPTION n The LTC 1428-50 is a micropower 8-bit current sink Precision Full-Scale DAC Output Current output D/A converter (DAC) with an output range of 0A to at 25C: 50A 3% n 50A. In 3.3V or 5V systems, the DAC I pin can be Wide Output Voltage DC Compliance: 2V to 10V OUT n biased from 2V to 10V. Supply current is only 130A. Wide Supply Range: 3V V 6.5V CC Shutdown mode drops the supply current to 0.2A. n Supply Current in Shutdown: 0.2A n Low Supply Current: 130A The LTC1428-50 communicates with external circuitry by n Available in 8-Pin SO using one of three interface modes: standard 3-wire serial TM n Triple Mode Interface mode or one of two pulse modes. Upon power-up, the 1. Standard 3-Wire Mode internal counter resets to 10000000B, the DAC output 2. 1-Wire Pulse Mode Interface: Increment-Only assumes midrange and the chip configures to 3-wire or 3. 2-Wire Pulse Mode Interface: Increment/Decrement pulse mode depending on the CS signal level. n DAC Value Read Back Capability in 3-Wire Mode In 3-wire mode, the system MPU can serially transfer n DAC Powers Up at Midrange 8-bit data to and from the LTC1428-50. In pulse mode, the n DAC Contents Are Retained in Shutdown upper six bits of the DAC output program for increment- only (1-wire interface) or increment/decrement (2-wire U interface) operation depending on the D signal level. In IN APPLICATIONS increment-only mode, the counter rolls over and sets the n LCD Contrast Control DAC to zero if the counter increases beyond full scale. In n Backlight Brightness Control increment/decrement mode, the counter stops n Power Supply Voltage Adjustment incrementing at full scale, stops decrementing at zero n scale and does not roll over. Battery Charger Voltage/Current Adjustment n GaAs FET Bias Adjustment LTC1428-50 is available in an 8-pin SO package. n Trimmer Pot Elimination , LTC and LT are registered trademarks of Linear Technology Corporation. Triple Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATION Digitally Controlled LCD Bias Generator (Standard 3-Wire Mode) D1 V L1 OUT 15.75V TO 27.75V IN STEPS OF 47mV 15mA FROM 2 CELLS R1 C1 5V 240k 0.1F V 1 8 IN I D OUT OUT SHDN SHDN SW 2 7 LT 1307 R2 V D 2 CC IN 1F 22k FB CELLS LTC1428-50 GND V C V CC 3 6 SHDN GND R3 4700pF MPU 4 5 22k (e.g., 8051) CLK CS 100k P1.3 P1.2 L1: 4.7H MURATA-ERIE LQH3C P1.1 D1: MBR0530 OR 1N4148 P1.0 1428-50 TA01 1 U ULTC1428-50 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) ORDER PART TOP VIEW Supply Voltage (V ) ................................................ 7V CC NUMBER Input Voltage (All Inputs)............ 0.3V to (V + 0.3V) I 1 8 D CC OUT OUT LTC1428CS8-50 Output Voltage V 2 7 D (UP/DN) CC IN I ...................................................... 0.3V to 10V SHDN GND 3 6 OUT D ....................................... 0.3V to (V + 0.3V) CLK CS 4 5 OUT CC S8 PART MARKING Short-Circuit Duration (All Outputs) ............... Indefinite S8 PACKAGE 8-LEAD PLASTIC SO Operating Temperature Range .................... 0C to 70C 14285 T = 125C, = 130C/ W JMAX JA Storage Temperature Range ................. 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C Consult factory for Industrial and Military grade parts. V = 3.3V, T = 25C, unless otherwise specified. ELECTRICAL CHARACTERISTICS CC A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V l 3.0 6.5 V CC I Supply Current V = V = V = V , V = 0V, D = NC, I = NC l 130 225 A CC SHDN DIN CS CC CLK OUT OUT Shutdown l 0.2 10 A DAC Resolution 8 Bits DAC Full-Scale Current I Bias Voltage = 2.5V 48.5 50 51.5 A OUT l 47.5 50 52.5 A DAC Zero-Scale Current I Bias Voltage = 2.5V l 200 nA OUT DAC Differential Monotonicity Guaranteed, No Missing Codes l 0.9 LSB Nonlinearity Supply Voltage Rejection V = 3V to 6.5V, Full Scale Current, I Bias Voltage = 2.5V l 1 4 LSB CC OUT Output Voltage Rejection V = 5V, Full Scale Current, l 1 LSB CC 2V V(I ) 3V OUT V = 5V, Full Scale Current, l 1 4 LSB CC 3V V(I ) 10V OUT Logic Input Current 0V V V l 1 A IN CC V High Level Input Voltage V = 5V l 2.0 V IH CC V = 3.3V l 1.9 V CC V Low Level Input Voltage V = 5V l 0.80 V IL CC V = 3.3V l 0.45 V CC V High Level Output Voltage V = 5V, I = 400A l 2.4 V OH CC O V = 3.3V, I = 400A l 2.1 V CC O V Low Level Output Voltage V = 5V, I = 2mA l 0.4 V OL CC O V = 3.3V, I = 1mA l 0.4 V CC O I Three-State Output Leakage V = V l 5 A OZ CS CC 2 U W U W U WW