CHESTER-X5
The CHESTER-X5 is a 2-channel isolated voltage-input extension module for the CHESTER platform.
Module Overview
CHESTER-X5 provides two isolated voltage inputs, each measuring −50 V to +50 V. Each channel uses a reinforced isolated amplifier (AMC3330) with an integrated isolated DC-DC converter, so the input is galvanically isolated from the CHESTER electronics and from the other channel. A precision 0.1% resistor divider scales the ±50 V input to the amplifier, and its differential output is digitized by a shared 24-bit ADS122C04 I²C ADC, channel 1 on AIN0/AIN1 and channel 2 on AIN2/AIN3.
Each channel's isolated amplifier is powered through its own load switch (TPS22917), so firmware can enable the channels independently and keep them off when idle to save energy. The ADC signals new samples on its data-ready line, which is routed to the slot's GP0 pin.
Key Features
- Two Isolated Inputs: Two independent voltage channels, each with reinforced galvanic isolation.
- ±50 V Range: Each channel measures −50 V to +50 V.
- Precision Acquisition: AMC3330 isolated amplifiers with 0.1% input dividers and a 24-bit ADS122C04 ADC.
- I²C Interface: The ADC is read over I²C; data-ready is signalled on GP0/A0.
- Per-Channel Power Switching: Each channel is powered through its own load switch (enabled via GP2 for channel 1, GP1 for channel 2) for low-power operation.
Typical Applications
- Isolated Voltage Measurement: Measuring voltages that must be galvanically separated from the logic.
- Floating / High-Side Voltages: Measuring signals that are not referenced to the system ground.
- Battery & Cell Monitoring: Monitoring battery, cell, or module voltages.
- Industrial Signal Measurement: Industrial voltages where isolation is required for safety or accuracy.
- Ground-Loop-Free Measurement: Avoiding ground loops between the measured circuit and the CHESTER node.
Technical Specifications
| Parameter | Value |
|---|---|
| Module Type | 2-channel isolated voltage input |
| Channels | 2 (independent), reinforced galvanic isolation |
| Input Range | −50 V to +50 V per channel |
| Isolated Amplifier | AMC3330DWE (integrated isolated DC-DC), one per channel |
| ADC | ADS122C04 (24-bit, 4-channel, I²C) |
| Channel Mapping | Ch1 → AIN0/AIN1, Ch2 → AIN2/AIN3 |
| Host Interface | I²C; data-ready (DRDY) on GP0/A0 |
| I²C Address | 0x40 (default); 0x41 via solder bridge S1 |
| Channel Power Enable | GP2/A2 (channel 1), GP1/A1 (channel 2) |
| Logic Supply (VDD) | 3.0 V |
| Board Interface | Castellated holes on two opposite edges, soldered to the CHESTER mainboard |
| Hardware Revision | R2.1 |
Key Components
| Component | Part Number | Description |
|---|---|---|
| Isolated Amplifier (×2) | AMC3330DWE | Reinforced isolated amplifier with integrated isolated DC-DC; one per channel |
| ADC | ADS122C04IPW | 24-bit 4-channel I²C ADC digitizing both channels |
| Load Switch (×2) | TPS22917DBV | Per-channel power switch for the isolated amplifiers |
Pin Configuration
The module uses a standardized header layout compatible with CHESTER extension slots.
The pin configuration shown is for the CHESTER-M CGLS mainboard.
CHESTER-X5 Connector Pinout
| Pin | Signal | Type | Description |
|---|---|---|---|
| 1 | DNC | — | Do not connect (isolation spacing) |
| 2 | INP1 | Isolated Input | Channel 1 positive input |
| 3 | INM1 | Isolated Input | Channel 1 negative input |
| 4 | DNC | — | Do not connect (isolation spacing) |
| 5 | DNC | — | Do not connect (isolation spacing) |
| 6 | INM2 | Isolated Input | Channel 2 negative input |
| 7 | INP2 | Isolated Input | Channel 2 positive input |
| 8 | DNC | — | Do not connect (isolation spacing) |
Each channel measures −50 V to +50 V and is galvanically isolated from the CHESTER electronics and from the other channel. The DNC pins (1, 4, 5, 8) have nothing connected. Leave them unconnected; they provide spacing that preserves the isolation between the channels and the logic side.
Host Interface (I²C)
CHESTER-X5 is read over the standard I²C bus through the on-board ADS122C04 ADC, which digitizes both isolated channels (channel 1 on AIN0/AIN1, channel 2 on AIN2/AIN3). The slot pins are used as follows:
| CHESTER-X pin | Direction | Function |
|---|---|---|
| SDA / SCL | I²C | ADS122C04 communication |
| GP0 / A0 | Input | ADS122C04 data-ready (DRDY) |
| GP1 / A1 | Output | Enables channel 2 power (load switch) |
| GP2 / A2 | Output | Enables channel 1 power (load switch) |
The ADC's I²C address is 0x40 by default; setting solder bridge S1 changes it to 0x41, so two CHESTER-X5 modules can be used on one CHESTER without a conflict. GP3/A3 is not used.
Input Connection
Connect the voltage source for channel 1 to INP1 (pin 2) and INM1 (pin 3), and for channel 2 to INP2 (pin 7) and INM2 (pin 6).
Because the inputs are galvanically isolated, the measured circuit does not need to share a ground with the CHESTER node, and the two channels are isolated from each other. Leave the DNC pins (1, 4, 5, 8) unconnected. Enable the channel's power from firmware (channel 1 via GP2, channel 2 via GP1) before taking a measurement.
Do not exceed the −50 V to +50 V input range on either channel.
Enclosure Feed-Through
Two options bring the input wiring into the enclosure:
- Cable gland (default): route the conductors through a cable gland in the enclosure wall and wire them to the terminal block.
- Panel-mount connector (on request): an external connector in the enclosure wall lets the user plug in the cable, with no loose wiring inside. Available on request.
Compatible CHESTER Configurations
The CHESTER-X5 module can be used with various CHESTER mainboard configurations. Below are examples of compatible setups:
CHESTER-M (CGLS)
CHESTER-C4
Schematic Diagrams
The complete schematic (the two AMC3330 isolated input channels, their TPS22917 load switches, and the ADS122C04 ADC) is available as a PDF:
Module Drawing
