AN1309: Compensated Sensor Bar Graph Pressure Gauge
Design a pressure gauge using the MPX2100 sensor and LM3914 driver. Provides a 10-segment LED bar graph and 0.5V to 4.5V analog output compatible with MCU A/D inputs.
Overview
This application note details the design of a bar graph pressure gauge utilizing the Freescale MPX2100DP compensated semiconductor pressure sensor. The system converts differential pressure into a 0.5V to 4.5V analog output range, specifically designed for compatibility with microcontroller A/D inputs such as the MC68HC11. The circuit features an MC33274 quad op amp for signal conditioning, amplification, and level shifting, alongside an LM3914 driver for a 10-segment LED bar graph display. The document provides technical specifications for a 100 kPa full-scale measurement system, including a complete bill of materials, schematics, and calibration instructions for zero and full-scale adjustments.
Use Cases
- Differential pressure monitoring
- Vacuum gauge design
- Microcontroller-based pressure sensing
- Industrial pressure indicators
- Electronic bar graph displays
Topics
Referenced Parts
Freescale Semiconductor
The evaluation board shown in Figure 1 is supplied with an MPX2100DP sensor
MC33274P
Freescale Semiconductor
U3 Op Amp Freescale MC33274P
MC78L05ACP
Freescale Semiconductor
U1 5.0 V Regulator Freescale MC78L05ACP
MV57124A
General Instrument
D11 LED GI MV57124A
MV57164
General Instrument
D1-D10 Bar Graph LED GI MV57164
12SDP2
NKK Switches
S1 Switch NKK 12SDP2
LM3914N
National Semiconductor
U2 Bar Graph IC National LM3914N
2SV03
Augat
Terminal Block Augat 2SV03
TP1040100
Components Corporation
Test Point Terminal (Black) Components Corp. TP1040100
TP1040102
Components Corporation
Test Point Terminal (Red) Components Corp. TP1040102
TP1040104
Components Corporation
Test Point Terminal (Yellow) Components Corp. TP1040104
MC68HC11
Freescale Semiconductor
directly connected to a microcomputer A/D channel, such as one of the E ports on an MC68HC11.
| 3386P-1-102 | Bourns | R1 Trimpot 1.0K Bourns 3386P-1-102 |
| 3386P-1-201 | Bourns | R11 Trimpot 200 Bourns 3386P-1-201 |
| MPX2100DP | Freescale Semiconductor | The evaluation board shown in Figure 1 is supplied with an MPX2100DP sensor |
| 3386P-1-102 | Bourns | 200 | Bourns | Bourns | 3386P-1-102 | 3386P-1-201 |
| MC33274P | Freescale Semiconductor | U3 Op Amp Freescale MC33274P |
| MC78L05ACP | Freescale Semiconductor | U1 5.0 V Regulator Freescale MC78L05ACP |
| MV57124A | General Instrument | D11 LED GI MV57124A |
| MV57164 | General Instrument | D1-D10 Bar Graph LED GI MV57164 |
| 12SDP2 | NKK Switches | S1 Switch NKK 12SDP2 |
| LM3914N | National Semiconductor | U2 Bar Graph IC National LM3914N |
| 2SV03 | Augat | Terminal Block Augat 2SV03 |
| TP1040100 | Components Corporation | Test Point Terminal (Black) Components Corp. TP1040100 |
| TP1040102 | Components Corporation | Test Point Terminal (Red) Components Corp. TP1040102 |
| TP1040104 | Components Corporation | Test Point Terminal (Yellow) Components Corp. TP1040104 |
| MC68HC11 | Freescale Semiconductor | directly connected to a microcomputer A/D channel, such as one of the E ports on an MC68HC11. |