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LTC1199LIMS8#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28
25
LTC1197/LTC1197L
LTC1199/LTC1199L
Figure 13. The LTC1199 Digitizes Resistive Touchscreen X and Y Axis Voltages. The ADC’s Auto Shutdown Feature
Helps Maximize Battery Life in Portable Touchscreen Equipment
Resistive Touchscreen Interface
Figure 13 shows the LTC1199 in a 4-wire resistive touch-
screen application. Transistor pairs Q1-Q3, Q2-Q4 apply
5V and ground to the X axis and Y axis, respectively. The
LTC1199, with its 2-channel multiplexer, digitizes the
voltage generated by each axis and transmits the conver-
sion results to the system’s processor through a serial
interface. RC combinations R1C1, R2C2 and R3C3 form
lowpass filters that attenuate noise from possible sources
such as the processor clock, switching power supplies
and bus signals. The 74HC14 inverter is used to detect
screen contact both during a conversion sequence and to
trigger its start. Using the single channel LTC1197, 5-wire
resistive touchscreens are as easily accommodated.
TYPICAL APPLICATIO S
U
C4
1000pF
C6
1000pF
C5
1000pF
R8
4.7k
R11
100k
R12
100k
R6
4.7k
R3
10Ω
R7
100k
R1
100Ω
LTC1199
R2
100Ω
R7
100k
R9
100k
Q1
2N2907
Q3
2N2222A
Q2
2N2907
R10
4.7k
74HC14
R6
4.7k
5V
Y
+
X
–
Y
–
X
+
TOUCH SENSE
CHIP SELECT
SERIAL CLK
DATA IN
DATA OUT
Q4
2N2222A
C7
1000pF
C2
1µF
C1
1µF
1197/99 F13
C3
10µF
1
2
3
4
8
7
6
5
V
CC
CLK
D
OUT
D
IN
CS
CH0
CH1
GND
+
26
LTC1197/LTC1197L
LTC1199/LTC1199L
Battery Current Monitor
The LTC1197L/LTC1199L are ideal for 3V systems. Fig-
ure 14 shows a 2.7V to 4V battery current monitor that
draws only 45µA at 3V from the battery it monitors,
sampling at a 1Hz rate. To minimize supply current, the
microprocessor uses the LTC1152 SHDN pin to turn on
the op amp prior to making a measurement and then turn
it off after the measurement has been made. The battery
current is sensed with the 0.005Ω resistor and amplified
by the LTC1152. The LTC1197L digitizes the amplifier
output and sends it to the microprocessor in serial
format. After each sample the LTC1197L automatically
powers down. The LT1004 provides the full-scale refer-
ence for the ADC. The circuit’s 45µA supply current is
dominated by the reference and the op amp. The circuit
can be located near the battery and data transmitted
serially to the microprocessor.
Figure 14. This 0A to 2A Battery Current Monitor Draws Only 45µA from a 3V Battery
TYPICAL APPLICATIO S
U
–
+
LTC1152
SHDN
240k
56k TO µP
100Ω
2k
0.005Ω
2A FULL
SCALE
500pF
2.7V
TO 4V
1µF
1µF
0.1µF
LT1004-1.2
1
2
3
4
8
7
6
5
CS
+IN
–IN
GND
V
CC
CLK
D
OUT
V
REF
LTC1197L
L
O
A
D
+
27
LTC1197/LTC1197L
LTC1199/LTC1199L
Dimensions in inches (millimeters), unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
MSOP (MS8) 1100
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.021
± 0.006
(0.53 ± 0.015)
0
° – 6° TYP
SEATING
PLANE
0.007
(0.18)
0.043
(1.10)
MAX
0.009 – 0.015
(0.22 – 0.38)
0.005
± 0.002
(0.13 ± 0.05)
0.034
(0.86)
REF
0.0256
(0.65)
BSC
12
3
4
0.193 ± 0.006
(4.90 ± 0.15)
8
7
6
5
0.118 ± 0.004*
(3.00 ± 0.102)
0.118 ± 0.004**
(3.00 ± 0.102)
0.016 – 0.050
(0.406 – 1.270)
0.010 – 0.020
(0.254 – 0.508)
× 45°
0°– 8° TYP
0.008 – 0.010
(0.203 – 0.254)
SO8 1298
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
TYP
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
1
2
3
4
0.150 – 0.157**
(3.810 – 3.988)
8
7
6
5
0.189 – 0.197*
(4.801 – 5.004)
0.228 – 0.244
(5.791 – 6.197)
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
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.
U
PACKAGE DESCRIPTIO
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LTC1199LIMS8#TRPBF

Mfr. #:
Buy LTC1199LIMS8#TRPBF
Manufacturer:
Analog Devices Inc.
Description:
Analog to Digital Converters - ADC 210ksps 2/Ch input 3V,10-Bit ADC
Lifecycle:
New from this manufacturer.
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