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TMP7 IC
Thermometer with Seven Segment and Serial Output
General Description
The TMP7 is thermometer IC with seven segment outputs for non multiplexed displays. An
inexpensive thermister is used as the temperature sensor. The IC supports 4 scales: degrees C,
degrees F, percentage, and raw A/D output. Serial output is also provided for RS-232, USB, or
Ethernet operation. The chip provides output polarity control. The TMP7 has internal pull
resistors on inputs to minimize additional parts. A .1 uF bypass capacitor is suggested across the
VDD and VSS pins. The part uses the standard 28 pin .3 inch width SOIC and DIP packages.
Features
•
Degrees C, Degrees F, percentage
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
and raw data outputs.
Can drive seven segment displays
and serial devices.
Minimum and maximum
temperatures.
Percentage scale.
12 bit A/D converter
Few external parts required.
Low power consumption 20 mA
typical.
Supply voltage 3.3 to 5.25 volts.
All timing internally generated.
On chip input resistors.
Output polarity select.
TTL and CMOS compatible.
Part is in full production.
SOIC and DIP 28 Pin Package.
ROHS Compliant
Low EMI
Applications
•
Temperature displays.
•
Remote temperature sensing.
•
Remote 12 bit A/D converter.
•
Environmental and process controls .
•
Percentage displays.
Part Number TMP7
Copyright © 2014 ABCircuits. Revised September 2014 Page 1 of 10
Turning Ideas Into Reality
ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104
Example Circuit – Stand Alone Thermometer
OPTIONAL 3RD COMMON
ANODE DISPLAY
VCC
COM
B
TMP7
SEG3G
SEG3C
SEG3B
10
5
2
G
C
B
G
C
VCC
10K
VCC
28
19
9
25
VDD
NC
NC
SOUT-
SEGLG
SEGLF
SEGLE
SEGLD
SEGLC
SEGLB
SEGLA
23
6
22
7
21
8
20
LEFT COMMON ANODE
DISPLAY
VCC
G
F
E
D
C
B
A
A
COM
F
G
E
D
C
B
10K NTC
t
OPTIONAL SWITCHES
24
TEMP
SEGRG
SEGRF
SEGRE
SEGRD
SEGRC
SEGRB
SEGRA
18
11
17
12
16
13
15
RIGHT COMMON
ANODE DISPLAY
G
F
E
D
C
B
A
A
COM
F
G
E
D
C
B
VCC
4
3
1
26
27
14
MAX-
MIN-
FARH
SCALE
POL
VSS
MAX
MIN
F/C
Example Circuit – Ethernet Thermometer
TMP7
+3.3
10K
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FARH
SEG3B
MIN-
MAX-
SEG3C
SEGLF
SEGLD
SEGLB
NC
SEG3G
SEGRF
SEGRD
SEGRB
VSS
VDD
POL
SCALE
SOUT-
TEMP
SEGLG
SEGLE
SEGLC
SEGLA
NC
SEGRG
SEGRE
SEGRC
SEGRA
28
27
26
25
24
23
22
21
20
19
18
17
16
15
+3.3
+3.3
LANTRONIX
XPORT
1
2
3
4
5
6
7
8
GND
+3.3
-POR
OUT
IN
CP1
CP2
CP3
ETHERNET
10K NTC
t
Part Number TMP7
Copyright © 2014 ABCircuits. Revised September 2014 Page 2 of 10
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ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104
Example Circuit – USB Thermometer
VCC
.01 BEAD .1
4.7
.1
20
4
17
FT232-SSOP
TXD
RXD
DTR
-CTS
RTS
RI
DSR
DCD
CBUS0
CBUS1
CBUS2
CBUS3
CBUS4
1
5
2
11
3
6
9
10
23
22
13
14
12
VCC
10K
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FARH
SEG3B
MIN-
MAX-
SEG3C
SEGLF
SEGLD
SEGLB
NC
SEG3G
SEGRF
SEGRD
SEGRB
VSS
TMP7
VDD
POL
SCALE
SOUT-
TEMP
SEGLG
SEGLE
SEGLC
SEGLA
NC
SEGRG
SEGRE
SEGRC
SEGRA
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VCC
USB
1
2
3
4
5
16
15
19
27
28
8
24
USBM
USBP
-RST
OSCI
OSCO
NC
NC
GND
GND
GND
AGND
TEST
CASE
VCC
VCCIO
3VOUT
10K NTC
REFER TO FT232 DATASHEET
FOR MORE DETAILS
t
Example Circuit – RS-232 Thermometer
VCC
U2
SEE NOTES
VCC
V+
V-
2
.1
6
.1
14
7
13
8
1
2
3
4
5
6
7
8
9
8
RS232
DB9S
VCC
10K
TXD
RXD
GND
10K NTC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FARH
SEG3B
MIN-
MAX-
SEG3C
SEGLF
SEGLD
SEGLB
NC
SEG3G
SEGRF
SEGRD
SEGRB
VSS
TMP7
VDD
POL
SCALE
SOUT-
TEMP
SEGLG
SEGLE
SEGLC
SEGLA
NC
SEGRG
SEGRE
SEGRC
SEGRA
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VCC
16
.1
3
4
.1
5
11
10
12
9
C1+
C1-
C2+
C2-
T1in
T2in
VCC
1
T1out
T2out
R1in
R2in
R1out
GND
R2out
7
18
21
25
26
t
U2= MAX232 FOR 5V RS232
U2= MAX3232 FOR 3V RS232
Part Number TMP7
Copyright © 2014 ABCircuits. Revised September 2014 Page 3 of 10
15
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ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104
Example Circuit – Percentage Display
OPTIONAL 3RD COMMON
ANODE DISPLAY
VCC
COM
B
TMP7
SEG3G
SEG3C
SEG3B
10
5
2
G
C
B
G
C
VCC
28
19
9
25
VCC
VDD
NC
NC
SOUT-
SEGLG
SEGLF
SEGLE
SEGLD
SEGLC
SEGLB
SEGLA
23
6
22
7
21
8
20
LEFT COMMON ANODE
DISPLAY
VCC
G
F
E
D
C
B
A
A
COM
F
G
E
D
C
B
24
TEMP
SEGRG
SEGRF
SEGRE
SEGRD
SEGRC
SEGRB
SEGRA
18
11
17
12
16
13
15
RIGHT COMMON
ANODE DISPLAY
G
F
E
D
C
B
A
A
COM
F
G
E
D
C
B
VCC
4
3
1
26
27
14
MAX-
MIN-
FARH
SCALE
POL
VSS
Connection Diagram
TMP7
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FARH
SEG3B
MIN-
MAX-
SEG3C
SEGLF
SEGLD
SEGLB
NC
SEG3G
SEGRF
SEGRD
SEGRB
VSS
VDD
POL
SCALE
SOUT-
TEMP
SEGLG
SEGLE
SEGLC
SEGLA
NC
SEGRG
SEGRE
SEGRC
SEGRA
28
27
26
25
24
23
22
21
20
19
18
17
16
15
Part Number TMP7
Copyright © 2014 ABCircuits. Revised September 2014 Page 4 of 10
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ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104
Pin Description
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Description
FARH
SEG3B
MIN-
MAX-
SEG3C
SEGLF
SEGLD
SEGLB
NC
SEG3G
SEGRF
SEGRD
SEGRB
VSS
Pin #
28
27
26
25
24
23
22
21
20
19
18
17
16
15
Description
VDD
POL
SCALE
SOUT-
TEMP
SEGLG
SEGLE
SEGLC
SEGLA
NC
SEGRG
SEGRE
SEGRC
SEGRA
POL
Polarity input. If this pin is open or high, the “on” segments will have a high level on the SEG
outputs of the chip. If this pin is low or grounded “on” segments will output as a low on the SEG
pins. This pin is read once at power up and has a built in pull up resistor.
TEMP
This is the analog input for the temperature. A 10K precision resistor and a 10K NTC thermister
are connected to this input for temperature measurement. The thermister should have a B25/B5
ratio of 3977K. These thermisters are available from Murata, Vishay, US Sensor, and other
companies. This input is a sensitive analog input and should be protected from noise.
This input may also be connected to any analog device with an output of 0 to VCC volts. In this
case, the input must be protected from voltages greater than VCC or lower than ground.
MIN-
This optional input displays the lowest temperature since power was applied. If both MIN- and
MAX- are low, the minimum temperature is reset to the current temperature. This input has a
built in pull up resistor. This input has no effect on the serial output.
MAX-
This optional input displays the highest temperature since power was applied. If both MIN- and
MAX- are low, the maximum temperature is reset to the current temperature. This input has a
built in pull up resistor. This input has no effect on the serial output.
SCALE and FARH
These two inputs select the scale to be used, degrees C, degrees F, Percentage, or Raw data.
These inputs have a built in pull up resistors. These inputs are read before every display update
and serial output.
Part Number TMP7
Copyright © 2014 ABCircuits. Revised September 2014 Page 5 of 10