LTC1286 Linear Technology, LTC1286 Datasheet - Page 23

• Manufacturer Part Number: LTC1286
• Description: Micropower Sampling 12-Bit A/D Converters In S0-8 Packages
• Manufacturer: Linear Technology

Figure 13. “Quick Look” Circuit for the LTC1286
A “Quick Look” Circuit for the LTC1286
Users can get a quick look at the function and timing of the
LT1286 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.
V
TYPICAL APPLICATIONS
IN
REF
Figure 14. Scope Trace the LTC1286 “Quick Look” Circuit
Showing A/D Output 101010101010 (AAA
+IN
–IN
GND
V
is tied to V
REF
LTC1286
NULL
BIT
4.7 F
D
CLK
V
OUT
CS
CC
CC
(B11)
MSB
. V
TO OSCILLOSCOPE
5V
IN
is applied to the +IN input and the
VERTICAL: 5V/DIV
HORIZONTAL: 10µs/DIV
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 circuits as described herein will not infringe on existing patent rights.
pin can be viewed on an
CLOCK IN 250kHz
OUT
U
outputs the data. The
CLR
CLK
A
B
C
D
P
GND
(B0)
LSB
HEX
74C161
N
)
LOAD
V
CC
RC
QA
QB
QC
QD
LTC1286/98 F14
T
LTC1286/98 F13
5V
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
67 A from the 5V supply at f
55 A from the battery. The 12-bits of resolution of the
LTC1286 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
200k
91k
39k
LT1004-2.5
REF
LTC1286/LTC1298
3
1 F
to 2V
SMPL
0.1 F
REF
= 0.1kHz and 25 A to
+IN
–IN
(2.5V to 5V). The
V
REF
LTC1286
V
5V
CC
GND
23
LTC1286/98 F15
CS
CLK
D
OUT