LTC1285 Datasheet, PDF (1/24 Pages) Linear Technology – 3V Micropower Sampling 12-Bit A/D Converters in SO-8 Packages

FEATURES
s _{12-Bit Resolution}
s _{8-Pin SO Plastic Package}
s _{Low Cost}
s _{Low Supply Current: 160µA Typ}
s _{Auto Shutdown to 1nA Typ}
s _{Guaranteed ±3/4LSB Max DNL}
s _{Single Supply 3V to 6V Operation}
s _{Differential Inputs (LTC1285)}
s _{2-Channel MUX (LTC1288)}
s _{On-Chip Sample-and-Hold}
s _{100µs Conversion Time}
s _{Sampling Rates:}
7.5ksps (LTC1285)
6.6ksps (LTC1288)
s _{I/O Compatible with SPI, Microwire, etc.}
APPLICATIONS
s _{Pen Screen Digitizing}
s _{Battery-Operated Systems}
s _{Remote Data Acquisition}
s _{Isolated Data Acquisition}
s _{Battery Monitoring}
s _{Temperature Measurement}
LTC1285/LTC1288
3V Micropower Sampling
12-Bit A/D Converters in
SO-8 Packages
DESCRIPTION
The LTC^®1285/LTC1288 are 3V micropower, 12-bit, suc-
cessive approximation sampling A/D converters. They
typically draw only 160µA of supply current when con-
verting and automatically power down to a typical supply
current of 1nA whenever they are not performing conver-
sions. They are packaged in 8-pin SO packages and
operate on 3V to 6V supplies. These 12-bit, switched-
capacitor, successive approximation ADCs include
sample-and-holds. The LTC1285 has a single differential
analog input. The LTC1288 offers a software selectable
2-channel MUX.
On-chip serial ports allow efficient data transfer to a wide
range of microprocessors and microcontrollers over three
wires. This, coupled with micropower consumption, makes
remote location possible and facilitates transmitting data
through isolation barriers.
These circuits can be used in ratiometric applications or
with an external reference. The high impedance analog
inputs and the ability to operate with reduced spans (to
1.5V full scale) allow direct connection to sensors and
transducers in many applications, eliminating the need for
gain stages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIONS N
12µW, S0-8 Package, 12-Bit ADC
Samples at 200Hz and Runs Off a 3V Supply
1µF 3V
1
V_REF
8
V_CC
2
7
ANALOG INPUT
0V TO 3V RANGE
+IN
CLK
3
LTC1285
–IN
D_OUT
6
4
5
GND CS/SHDN
MPU
(e.g., 8051)
P1.4
P1.3
P1.2
SERIAL DATA LINK
LTC1285/88 • TA01
Supply Current vs Sample Rate
1000
T_A = 25°C
V_CC = 2.7V
V_REF = 2.5V
f_CLK = 120kHz
100
10
1
0.1
1
10
100
SAMPLE FREQUENCY (kHz)
LTC1285/88 • TA02
1