Datasheet LTC1286, LTC1298 (Analog Devices) - 9

LTC1286/LTC1298
TEST CIRCUITS Voltage Waveforms for tdis Voltage Waveforms for ten
LTC1286 CS VIH CS DOUT 90% WAVEFORM 1 (SEE NOTE 1) CLK 1 2 tdis DOUT WAVEFORM 2 10% (SEE NOTE 2) B11 D NOTE 1: WAVEFORM 1 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH OUT VOL THAT THE OUTPUT IS HIGH UNLESS DISABLED BY THE OUTPUT CONTROL. t NOTE 2: WAVEFORM 2 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH en LTC1286/98 • TC06 THAT THE OUTPUT IS LOW UNLESS DISABLED BY THE OUTPUT CONTROL. LTC1286/98 • TC05
Voltage Waveforms for ten
LTC1298 CS DIN START CLK 1 2 3 4 B11 DOUT VOL ten LTC1286/98 • TC07
U U W U APPLICATION INFORMATION OVERVIEW
while the LTC1298 operates from a 4.5V to 5.5V supply. The LTC1286 and LTC1298 are micropower, 12-bit, suc- Both the LTC1286 and the LTC1298 contain a 12-bit, cessive approximation sampling A/D converters. The switched-capacitor ADC, a sample-and-hold, and a LTC1286 typically draws 250µA of supply current when serial port (see Block Diagram). Although they share sampling at 12.5kHz while the LTC1298 nominally con- the same basic design, the LTC1286 and LTC1298 sumes 350µA of supply current when sampling at differ in some respects. The LTC1286 has a differential 11.1 kHz. The extra 100µA of supply current on the input and has an external reference input pin. It can LTC1298 comes from the reference input which is inten- measure signals floating on a DC common-mode volt- tionally tied to the supply. Supply current drops linearly as age and can operate with reduced spans to 1V. Reduc- the sample rate is reduced (see Supply Current vs Sample ing the spans allows it to achieve 244µV resolution. The Rate). The ADCs automatically power down when not LTC1298 has a two-channel input multiplexer and can performing conversions, drawing only leakage current. convert either channel with respect to ground or the They are packaged in 8-pin SO and DIP packages. The difference between the two. The reference input is tied LTC1286 operates on a single supply from 4.5V to 9V, to the supply pin. 9