LTC1285/LTC1288 3V Micropower Sampling 12-Bit A/D Converters in SO-8 Packages FEATURES DESCRIPTION n 12-Bit Resolution The LTC 1285/LTC1288 are 3V micropower, 12-bit, suc- n 8-Pin SO Plastic Package cessive approximation sampling A/D converters. They n Low Cost typically draw only 160A of supply current when con- n Low Supply Current: 160A Typ verting and automatically power down to a typical supply n Auto Shutdown to 1nA Typ current of 1nA whenever they are not performing conver- n Guaranteed 3/4LSB Max DNL sions. They are packaged in 8-pin SO packages and n Single Supply 3V to 6V Operation operate on 3V to 6V supplies. These 12-bit, switched- n Differential Inputs (LTC1285) capacitor, successive approximation ADCs include n 2-Channel MUX (LTC1288) sample-and-holds. The LTC1285 has a single differential n On-Chip Sample-and-Hold analog input. The LTC1288 offers a software selectable n 100s Conversion Time 2-channel MUX. n Sampling Rates: On-chip serial ports allow efficient data transfer to a wide 7.5ksps (LTC1285) range of microprocessors and microcontrollers over three 6.6ksps (LTC1288) wires. This, coupled with micropower consumption, makes n I/O Compatible with SPI, Microwire, etc. remote location possible and facilitates transmitting data through isolation barriers. APPLICATIONS These circuits can be used in ratiometric applications or n Pen Screen Digitizing with an external reference. The high impedance analog n Battery-Operated Systems inputs and the ability to operate with reduced spans (to n Remote Data Acquisition 1.5V full scale) allow direct connection to sensors and n Isolated Data Acquisition transducers in many applications, eliminating the need for n Battery Monitoring gain stages. n Temperature Measurement , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIONS N 12W, S0-8 Package, 12-Bit ADC Supply Current vs Sample Rate Samples at 200Hz and Runs Off a 3V Supply 1000 T = 25C A V = 2.7V 1F 3V CC V = 2.5V REF f = 120kHz CLK 100 MPU (e.g., 8051) 1 8 V V P1.4 REF CC 2 7 10 +IN CLK P1.3 ANALOG INPUT LTC1285 3 6 0V TO 3V RANGE P1.2 IN D OUT SERIAL DATA LINK 4 5 GND CS/SHDN LTC1285/88 TA01 1 0.1 1 10 100 SAMPLE FREQUENCY (kHz) LTC1285/88 TA02 1 SUPPLY CURRENT (A) U U ULTC1285/LTC1288 ABSOLUTE MAXIMUM RATINGS (Notes 1 and 2) Supply Voltage (V ) to GND................................... 12V Power Dissipation .............................................. 500mW CC Voltage Operating Temperature Range .................... 0C to 70C Analog and Reference ................ 0.3V to V + 0.3V Storage Temperature Range ................. 65C to 150C CC Digital Inputs......................................... 0.3V to 12V Lead Temperature (Soldering, 10 sec.)................ 300C Digital Output ............................. 0.3V to V + 0.3V CC PACKAGE/ORDER INFORMATION ORDER PART TOP VIEW ORDER PART TOP VIEW NUMBER NUMBER V V 1 8 V V 1 8 REF CC REF CC +IN 2 7 CLK +IN 2 7 CLK LTC1285CN8 LTC1285CS8 IN IN 3 6 D 3 6 D OUT OUT GND 4 CS/SHDN GND CS/SHDN 5 4 5 PART MARKING N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO 1285C T = 150C, = 130C/W T = 150C, = 175C/W JMAX JA JMAX JA TOP VIEW TOP VIEW ORDER PART ORDER PART NUMBER NUMBER CS/SHDN 1 8 V (V ) CS/SHDN 1 8 V (V ) CC REF CC REF CH0 2 CLK 7 CH0 2 7 CLK LTC1288CN8 LTC1288CS8 CH1 3 6 D 3 6 D OUT CH1 OUT GND 4 5 D GND 4 5 D IN IN PART MARKING N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO T = 150C, = 130C/W T = 150C, = 175C/W 1288C JMAX JA JMAX JA Consult factory for Industrial and Military grade parts. RECOM ENDED OPERATING CONDITIONS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Supply Voltage (Note 3) LTC1285 2.7 6 V CC LTC1288 2.7 6 V f Clock Frequency V = 2.7V (Note 4) 120 kHz CLK CC t Total Cycle Time LTC1285, f = 120kHz 125.0 s CYC CLK LTC1288, f = 120kHz 141.5 s CLK t Hold Time, D After CLK V = 2.7V 450 ns hDI IN CC t Setup Time CS Before First CLK (See Operating Sequence) LTC1285, V = 2.7V 2 s suCS CC LTC1288, V = 2.7V 2 s CC t Setup Time, D Stable Before CLK V = 2.7V 600 ns suDI IN CC t CLK High Time V = 2.7V 3.5 s WHCLK CC t CLK Low Time V = 2.7V 3.5 s WLCLK CC t CS High Time Between Data Transfer Cycles V = 2.7V 2 s WHCS CC t CS Low Time During Data Transfer LTC1285, f = 120kHz 123.0 s WLCS CLK LTC1288, f = 120kHz 139.5 s CLK 2 U U U U WW UUW WWW