LTC1285/LTC1288
3V Micropower Sampling
12-Bit A/D Converters in
SO-8 Packages
DESCRIPTION
The LTC
廬
1285/LTC1288 are 3V micropower, 12-bit, suc-
cessive approximation sampling A/D converters. They
typically draw only 160碌A(chǔ) 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.
FEATURES
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12-Bit Resolution
8-Pin SO Plastic Package
Low Cost
Low Supply Current: 160碌A(chǔ) Typ
Auto Shutdown to 1nA Typ
Guaranteed
鹵3/4LSB
Max DNL
Single Supply 3V to 6V Operation
Differential Inputs (LTC1285)
2-Channel MUX (LTC1288)
On-Chip Sample-and-Hold
100碌s Conversion Time
Sampling Rates:
7.5ksps (LTC1285)
6.6ksps (LTC1288)
I/O Compatible with SPI, Microwire, etc.
APPLICATIONS
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Pen Screen Digitizing
Battery-Operated Systems
Remote Data Acquisition
Isolated Data Acquisition
Battery Monitoring
Temperature Measurement
TYPICAL APPLICATIONS
N
12碌W, S0-8 Package, 12-Bit ADC
Samples at 200Hz and Runs Off a 3V Supply
1碌F
3V
Supply Current vs Sample Rate
1000
T
A
= 25擄C
V
CC
= 2.7V
V
REF
= 2.5V
f
CLK
= 120kHz
100
MPU
(e.g., 8051)
1
2
V
REF
V
CC
8
7
P1.4
P1.3
P1.2
SERIAL DATA LINK
LTC1285/88 鈥?TA01
SUPPLY CURRENT (碌A(chǔ))
CLK
+IN
ANALOG INPUT
LTC1285
3
6
0V TO 3V RANGE
鈥揑N
D
OUT
4
5
CS/SHDN
GND
10
1
0.1
1
10
SAMPLE FREQUENCY (kHz)
100
U
U
U
LTC1285/88 鈥?TA02
1