MICROCHIP TC7136, TC7136A Technical data
TC7136/TC7136A
Low Power 3-1/2 Digit Analog-to-Digital Converter
Features
• Fast Over Range Recovery, EnsuredFirst Reading
Accuracy
• Low Temperature Drift Internal Reference
- TC7136: 70ppm/°C (Typ.)
- TC7136A: 35ppm/°C (Typ.)
• Zero Reading with Zero Input
• Low Noise: 15µV
• High Resolution: 0.05%
• Low Input Leakage Current:1pA (Typ.)/10pA (Max.)
• PrecisionNull Detectors with True Polarity at Zero
• High-ImpedanceDifferential Input
• Convenient 9V Battery Operation with Low Power
Dissipation: 500µW (Typ.)/900µW(Max.)
P-P
Applications
• Thermometry
• Bridge Readouts: Strain Gauges, Load Cells,
Null Detectors
• Digital Meters: Voltage/Current/Ohms/Power, pH
• Digital Scales, Process Monitors
• PortableInstrumentation
Device Selection Table
Part Number Package
TC7136CPI 40-PinPDIP 0°Cto+70°C
TC7136CKW 44-Pin PQFP 0°Cto+70°C
TC7136CLW 44-Pin PLCC 0°Cto+70°C
TC7136A CPI 40-PinPDIP 0°Cto+70°C
TC7136A CKW 44-Pin PQFP 0°Cto+70°C
TC7136A CLW 44-PinP LCC 0°Cto+70°C
Temperature
Range
General Description
The TC7136 and TC7136A are low power, 3-1/2 digit
with liquid crystal display (LCD) drivers and analog-todigital converters. These devices incorporate an "integrator output zero" phase, which enables over range
recovery. The performance of existing TC7126,
TC7126A and ICL7126 based systems may be
upgraded with minor changes to external, passive
components.
The TC7136A has an improved i nternal zener reference voltage circuit which maintains the analog common temperature drift to 35ppm/°C (typical) and
75ppm/°C (maximum). This represents an improvement of two to four times over similar 3-1/2 digit converters. The costly, space consuming external
reference source may be removed.
The TC7136 and TC7136A limit linearity error to less
than1 count on200mV or 2V full scaleranges.Therollover error (the difference in readings for equal magnitude, but opposite polarity input signals) is below ±1
count. High-impedance differential inputs offer 1pA
leakage currents and a 10
differential reference input allows ratiometric measurements for ohms or bridge transducer measurements.
The 15µV
reading. The auto-zero cycle enables a zero display
readout for a 0V input.
noise performance ensures a "rock solid"
P-P
12
Ω input impedance. The
2002 Microchip TechnologyInc. DS21461B-page 1
TC7136/TC7136A
Package Type
1
A
B1C1D1V+
6543 1442
F
7
1
G
8
1
E
9
1
D
10
2
C
11
2
12
NC
B
13
2
A
2
F
2
E
2
D
3
18 19 20 21 23 24
3
3
B
F
44-Pin PLCC
TC7136CLW
TC7136ACLW
22
4
3
E
AB
POL
40-Pin PDIP
OSC1
OSC242OSC341TEST40REF HI
NC
43
25 26 27 28
3A3C3
G
BP
NC
2
G
39
REF LO
C
38
C
37
ANALOG
36
COMMON
35
IN HI
34
NC
33
IN LO
3214
AZ
3115
BUFF
3016
INT
2917
V-
REF
REF
44-Pin PQFP
+
-
REF
REF LO
C
REF
ANALOG
COMMON
C
IN HI
IN LO
TC7136CKW
TC7136ACKW
16
2B2A2F2E2
2
C
D
BUFF35INT34V-
37AZ36
19 20 21 22
33
NC
32
G
2
C
31
3
30
A
3
29
G
3
BP
28
POL
27
26
AB
4
E
25
3
F
24
3
23
B
3
3
D
REF HI
44 43 42 41 39 3840
1
NC
2
+
-
NC
TEST
OSC3
NC
OSC2
OSC1
V+
D
C
B
3
4
5
6
7
8
9
1
10
1
11
1
12 13 14 15 17 18
1F1G1E1
A
40-Pin PDIP
1's
10's
100's
1000's
(MINUS SIGN)
V+
D
C
B
A
F
G
E
D
C
B
A
F
E
D
B
F
E
AB
POL
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
10
2
11
2
12
2
13
2
14
2
15
3
16
3
17
3
18
3
19
4
20
Normal Pin
Configuration
TC7136CPL
TC7136ACPL
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
OSC1
OSC2
OSC3
TEST
+
V
REF
V
-
REF
+
C
REF
C
-
REF
ANALOG
COMMON
+
V
IN
-
V
IN
C
AZ
V
BUFF
V
INT
V-
G
2
C
3
100's
A
3
G
3
BP
(Backplane)
NC = No Internal Connection
OSC1
OSC2
OSC3
TEST
V
REF
V
REF
C
REF
C
REF
ANALOG
COMMON
V
IN
V
IN
C
AZ
V
BUFF
V
INT
V-
G
C
100's
A
G
BP
(Backplane)
1
2
3
4
+
5
-
6
+
7
-
TC7136RCPL
8
TC7136ARCPL
9
+
10
-
11
12
13
14
15
16
2
17
3
18
3
19
3
20
Reverse Pin
Configuration
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
V+
D
1
C
1
B
1
A
1's
1
F
1
G
1
E
1
D
2
C
2
B
2
10's
A
2
F
2
E
2
D
3
B
3
100's
F
3
E
3
AB
1000's
4
POL
(Minus Sign)
DS21461B-page 2
2002 Microchip TechnologyInc.
Typical Application
TC7136/TC7136A
0.1µF
+
Analog
Input
–
1MΩ
0.01µF
180kΩ
0.15µF
0.47
µF
34
C
+
REF
31
+
V
IN
TC7136
30
32
28
29
27
TC7136A
-
V
IN
ANALOG
COMMON
V
BUFF
C
AZ
V
INT
39 38 40
R
OSC
560kΩ
33
C
REF
C
50pF
-
OSC
22-25
V
REF
V
OSC1OSC3OSC2
9-19
POL
REF
BP
V+
+
V-
Segment
Drive
20
21
1
36
35
26
LCD
Minus Sign
240kΩ
To Analog Common (Pin 32)
Backplane
10kΩ
1 Conversion/Sec
+
9V
2002 Microchip TechnologyInc. DS21461B-page 3
TC7136/TC7136A
T
Functional Block Diagram
V+
0.5mA
LCD
Output
Segment
2mA
BP
37
6.2V
Control Logic
4
÷
OSC
F
TES
V-
26
500Ω
= 1V
TH
V
Internal Digital Ground
OSC3OSC1
39
OSC2
OSC
R
OSC
C
V+
1
21
INT
C
200
÷
Decode
7-Segment
Decode
7-Segment
LCD Segment Drivers
Decode
7-Segment
Section
To Digital
INT
V
27333634
+
Tens Units
Data Latch
Hundreds
To Switch
Thousands
–
Clock
Typical Segment Input
Internal Digital Ground
AZ
C
V
INT
R
BUFF
V
-
REF
TC7136/A
C
-
REF
REF
C
+V
REF
V
+
REF
C
Integrator
29
1
28
35
–
–
ZI &
ZI & AZ
10
AZ
Comparator
+
AZ
REF
LOW
TEMPCO
V
ZI
+
µA
31
+
V
–
+
V+ – 2.8V
26
DE
(+)
(–)
DE
INT
IN
DE (–)
DE (+)
32
ANALOG
COMMON
AZ & DE (±)
-
IN
V
40 38
V-
INT
DS21461B-page 4
2002 Microchip TechnologyInc.
TC7136/TC7136A
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings*
Supply Voltage (V+ to V-).......................................15V
*Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device. These
are stress ratings only and functional operation of the device
at these or any other conditions above those indicated in the
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affectdevice reliability.
Analog Input Voltage(Either Input) (Note 1)... V+ to V-
Reference Input Voltage (Either Input)............ V+ to V-
Clock Input .................................................TEST to V+
Package Power Dissipation (T
≤ 70°C) (Note 2):
A
Plastic DIP ...................................................1.23W
Plastic Quad Flat Package ..........................1.00W
PLCC ...........................................................1.23W
Operating Temperature Range:
C Devices..........................................0°C to +70°C
I Devices ........................................-25°C to +85°C
StorageTemperature Range..............-65°C to +150°C
TC7136 AND TC7136A ELEC TRICAL SPECIFICATIONS
Electrical Characteristics: VS=9V,f
Symbol Parameter Min Typ Max Unit Test Conditions
Input
Zero Input Reading -000.0 ±000.0 +000.0 Digital
Zero Reading Drift — 0.2 1 µV/°C V
Ratiometric Reading 999 999/1000 1000 Digital
NL Non-Linearity Error — 1 ±0.2 Count Full Scale = 20mV or 2V Max.
E
R
e
N
I
L
CMRR Common Mode Rejection Ratio — 50 — µV/V V
TC
Note 1: Input voltages may exceed supply voltages when input current is limited to 100µA.
Rollover Error -1 -1 ±0.2 1 Count VIN-=VIN+ ≈ 200mV
Noise — 15 — µV
Input Leakage Current — 1 10 pA VIN=0V
Scale Factor T emperature
SF
Coefficient
2: Dissipationrating assumes deviceis mountedwithallleadssoldered to PC board.
3: Refer to "DifferentialInput" discussion.
4: Backplane drive is in phase with segment drive for "OFF" segment and 180° out-of-phase for "ON" segment. Frequency
is 20 times conversion rate. Average DC component is less than 50mV.
5: See "Typical Application".
6: A 48kHz oscillator increases current by 20µA (typical). Common currentnot included.
=16kHz,andTA= +25°C, unlessotherwise noted.
CLK
Reading
Reading
P-PVIN
—1 5ppm/°CV
= 0V, Full Scale = 200mV
V
IN
=0V,0°C≤ TA≤ +70°C
IN
V
IN=VREF,VREF
Deviation from best Straight Line
= 0V, Full Scale = 200mV
=±1V,VIN=0V,FullScale=200mV
CM
=199mV,0°C≤ TA≤ +70°C
IN
Ext. Ref. Temp. Coeff. = 0ppm/°C
= 100mV
2002 Microchip TechnologyInc. DS21461B-page 5
TC7136/TC7136A
TC7136 AND TC7136A ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Characteristics: VS=9V,f
Symbol Parameter Min Typ Max Unit Test Conditions
Analog Common
V
CTC
Analog Common Temperature
Coefficient
TC7136A — 35 75 ppm/°C 0°C ≤ T
TC7136 — 70 150 ppm/°C "C" Commercial Temp. Range Devices
TC7136A — 35 100 ppm/°C -25°C ≤ T
TC7136 — 70 150 ppm/°C "I" Industrial Temp. Range Devices
V
C
Analog Common Voltage 2.7 3.05 3.35 V 250kΩ Between Common and V+
LCD Drive
V
SD
V
BD
LCD Segment Drive Voltage 4 5 6 V
LCD Backplane Drive Voltage 4 5 6 V
Power Supply
I
S
Power Supply Current — 70 100 µAVIN=0V,V+toV-=9V(Note 6)
Note 1: Input voltages may exceed supply voltages when input current is limited to 100µA.
2: Dissipationrating assumes deviceis mountedwithallleadssoldered to PC board.
3: Refer to "DifferentialInput" discussion.
4: Backplane drive is in phase with segment drive for "OFF" segment and 180° out-of-phase for "ON" segment. Frequency
is 20 times conversion rate. Average DC component is less than 50mV.
5: See "Typical Application".
6: A 48kHz oscillator increases current by 20µA (typical). Common currentnot included.
=16kHz,andTA= +25°C, unlessotherwise noted.
CLK
P-P
P-P
250kΩ betweenCommonandV+
≤ +70°C
A
≤ +85°C
A
V+ to V- = 9V
V+ to V- = 9V
DS21461B-page 6
2002 Microchip TechnologyInc.
2.0 PIN DESCRIPTIONS
ThedescriptionsofthepinsarelistedinTable2-1.
TABLE 2-1: PIN DE SCRIPTION
Pin Number
(40-Pin PDIP)
Normal
1 (40) V+ Positive supply voltage.
2(39)D
3(38)C
4(37)B
5(36)A
6(35)F
7(34)G
8(33)E
9(32)D
10 (31) C
11 (30) B
12 (29) A
13 (28) F
14 (27) E
15 (26) D
16 (25) B
17 (24) F
18 (23) E
19 (22) AB
20 (21) POL Activates the negative polarity display.
21 (20) BP Backplane drive output.
22 (19) G
23 (18) A
24 (17) C
25 (16) G
26 (15) V- Negative power supply voltage.
27 (14) V
28 (13) V
29 (12) C
30 (11) V
31 (10) V
32 (9) ANALOG
33 (8) C
(Reverse) Symbol Description
Activates the D sectionof the units display.
1
Activates the C sectionof the units display.
1
Activates the B sectionof the units display.
1
Activates the A sectionof the units display.
1
Activates the F section of the units display.
1
Activates the G section of the units display.
1
Activates the E sectionof the units display.
1
Activates the D section of the tensdisplay.
2
Activates the C section of the tensdisplay.
2
Activates the B section of thetensdisplay.
2
Activates the A section of thetensdisplay.
2
Activates the F sectionof the tens display.
2
Activates the E section of thetensdisplay.
2
Activates the D section of the hundreds display.
3
Activates the B section of the hundreds display.
3
Activates the F section of the hundreds display.
3
Activates the E section of the hundreds display.
3
Activates both halves of the 1 in the thousands display.
4
Activates the G section of the hundreds display.
3
Activates the A section of the hundreds display.
3
Activates the C section of the hundreds display.
3
Activates the G section of the tens display.
2
INT
The integrating capacitor should be selected to give the maximum voltage swing
thatensures componenttolerance buildup willnotallowtheintegrator outputto saturate. When analog common is used as a reference and the conversion rate is 3
readings per second, a 0.047µF capacitor may be used. The capacitor must have a
low dielectric constant to prevent rollover errors. See Section 6.3, Integrating
Capacitor for additional details.
BUFF
AZ
Integration resistor connection. Use a 180kΩ fora 20mV full scale range and a
1.8MΩ for 2V full scale range.
The size of the auto-zero capacitor influences the system noise. Use a 0.47µF
capacitor for a 200mV full scale and a 0.1µF capacitor for a 2V full scale.
See Section 6.1, Auto-Zero Capacitor for more details.
- Thelow input signal is connected to this pin.
IN
+ The high input signal is connected to this pin.
IN
This pin is primarilyused to set the Analog Common mode voltagefor battery
COMMON
operation, or in systems where the input signal is referenced to the power supply.
See Section 7.3, Analog Common for more details. It also acts as a reference
voltage source.
-SeePin34.
REF
TC7136/TC7136A
2002 Microchip TechnologyInc. DS21461B-page 7
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