LTC1285IS8 Linear Technology, LTC1285IS8 Datasheet - Page 23

• Manufacturer Part Number: LTC1285IS8
• Description: IC A/D CONV SAMPLING 12BIT 8SOIC
• Manufacturer: Linear Technology

Specifications of LTC1285IS8

• Number Of Bits: 12
• Sampling Rate (per Second): 7.5k
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 480µW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

TYPICAL APPLICATIONS
A “Quick Look” Circuit for the LTC1285
Users can get a quick look at the function and timing of the
LT1285 by using the following simple circuit (Figure 13).
V
–IN input is tied to the ground. CS is driven at 1/16 the
clock rate by the 74C161 and D
output data from the D
oscilloscope that is set up to trigger on the falling edge of
CS (Figure 14). Note the LSB data is partially clocked out
before CS goes high.
REF
V
IN
Figure 14. Scope Trace the LTC1285 “Quick Look” Circuit
Showing A/D Output 101010101010 (AAA
is tied to V
+IN
–IN
GND
V
REF
Figure 13. “Quick Look” Circuit for the LTC1285
LTC1285
NULL
BIT
4.7 F
D
CC
CLK
V
OUT
CS
CC
(B11)
MSB
. V
2.7V
VERTICAL: 2V/DIV
HORIZONTAL: 20µs/DIV
TO OSCILLOSCOPE
IN
is applied to the +IN input and the
OUT
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
pin can be viewed on an
OUT
CLOCK IN 120kHz
U
outputs the data. The
LSB
(B0)
CLR
CLK
A
B
C
D
P
GND
HEX
N
74HC161
)
LTC1285/88 • F13
LOAD
V
CC
QD
RC
QA
QB
QC
T
Micropower Battery Voltage Monitor
A common problem in battery systems is battery voltage
monitoring. This circuit monitors the 10 cell stack of NiCad
or NiMH batteries found in laptop computers. It draws only
40 A from the 2.7V supply at f
62 A from the battery. The 12-bits of resolution of the
LTC1285 are positioned over the desired range of 8V to
16V. This is easily accomplished by using the ADC’s
differential inputs. Tying the –input to the reference gives
an ADC input span of V
resistor divider then scales the input voltage for 8V to 16V.
BATTERY MONITOR
INPUT 8V TO 16V
Figure 15. Micropower Battery Voltage Monitor
220k
39k
39k
LT1004-1.2
LTC1285/LTC1288
REF
3
to 2V
1 F
SMPL
0.1 F
REF
= 0.1kHz and 30 A to
+IN
–IN
(1.2V to 2.4V). The
V
REF
LTC1285
2.7V
V
CC
GND
LTC1285/88 • F15
23
CS
CLK
D
OUT