5.2 KiB
5.2 KiB
TXB0104PWR Datasheet Reference
Based on the official TXB0104 datasheet: TXB0104 Datasheet
Key Specifications
Power Supply Requirements
- VCCA (A Port): 1.2V to 3.6V
- Our design: 3.3V (for ESP32)
- Pin: Pin 12 (VCCA)
- VCCB (B Port): 1.65V to 5.5V
- Our design: 5V (for AC communication)
- Pin: Pin 11 (VCCB)
- Critical: VCCA must NOT exceed VCCB
- Our design: 3.3V ≤ 5V ✓ (correct)
Pin Configuration (TSSOP-14 Package - TXB0104PW)
| Pin | Name | Function | Our Connection |
|---|---|---|---|
| 1 | A1 | A Port 1 (Low Voltage) | ESP32 GPIO17 (TX) |
| 2 | A2 | A Port 2 (Low Voltage) | ESP32 GPIO16 (RX) |
| 3 | A3 | A Port 3 (Low Voltage) | NC (Not Connected) |
| 4 | A4 | A Port 4 (Low Voltage) | NC (Not Connected) |
| 5 | GND | Ground | GND |
| 6 | B4 | B Port 4 (High Voltage) | NC (Not Connected) |
| 7 | B3 | B Port 3 (High Voltage) | NC (Not Connected) |
| 8 | B2 | B Port 2 (High Voltage) | AC TX (J1 Pin 3) |
| 9 | B1 | B Port 1 (High Voltage) | AC RX (J1 Pin 2) |
| 10 | OE | Output Enable | +3V3 (VCCA) |
| 11 | VCCB | B Port Power Supply | +5V |
| 12 | VCCA | A Port Power Supply | +3V3 |
| 13 | GND | Ground | GND |
| 14 | GND | Ground | GND |
Critical Design Requirements
1. Output Enable (OE) Pin
Per Datasheet:
- OE input circuit is referenced to VCCA (not VCCB)
- When OE is LOW: All outputs are in high-impedance state
- When OE is HIGH: Device is enabled
- Power-up/down: OE must be tied to GND through a pulldown resistor to ensure high-impedance during power transitions
Our Design:
- OE (Pin 10): Connected to +3V3 (VCCA) ✓
- Note: We connect OE directly to VCCA (3.3V), which keeps the device always enabled
- Alternative: Could add pulldown resistor for power-up safety, but direct connection to VCCA is acceptable for always-on operation
Recommendation:
- Current design (OE → +3V3) is correct for always-enabled operation
- Optional: Add 10kΩ pulldown resistor from OE to GND for power-up safety (not critical if power sequencing is controlled)
2. Power Supply Sequencing
Per Datasheet:
- VCCA must not exceed VCCB
- VCC isolation: If either VCC input is at GND, all outputs are in high-impedance state
- IOFF supports partial power-down mode
Our Design:
- VCCA = 3.3V, VCCB = 5V ✓ (3.3V ≤ 5V, correct)
- Both supplies come from same source (J1 Pin 1 = +5V)
- 3.3V is derived from 5V via regulator
- Power sequencing: 5V comes first, then 3.3V (via regulator) - this is acceptable
3. Bidirectional Translation
Per Datasheet:
- Automatic direction sensing
- No direction control needed
- Works bidirectionally on A and B ports
Our Design:
- A1 (Pin 1) ↔ B1 (Pin 9): ESP32 TX ↔ AC RX ✓
- A2 (Pin 2) ↔ B2 (Pin 8): ESP32 RX ↔ AC TX ✓
- Automatic direction sensing handles UART communication ✓
4. Decoupling Capacitors
Per Datasheet:
- Recommended: 0.1µF (100nF) ceramic capacitor on VCCA
- Recommended: 0.1µF (100nF) ceramic capacitor on VCCB
- Place as close as possible to power pins
Our Design:
- VCCA (Pin 12): Should have 100nF capacitor to GND
- VCCB (Pin 11): Should have 100nF capacitor to GND
- Note: These are not explicitly listed in our component list - should be added
Recommendation:
- Add C14: 100nF from VCCA (Pin 12) to GND
- Add C15: 100nF from VCCB (Pin 11) to GND
Electrical Characteristics
- Low Power Consumption: 5µA maximum ICC
- ESD Protection: ±15kV on B port
- Latch-up Performance: Exceeds 100mA per JESD 78, Class II
- Operating Temperature: -40°C to +85°C
Package Information
TXB0104PW (TSSOP-14):
- Package: TSSOP (14-pin)
- Body Size: 5.00mm × 4.40mm
- Height: 1.2mm max
- Lead Pitch: 0.65mm (fine pitch)
- Footprint:
Package_SO:TSSOP-14_4.4x5mm_P0.65mm✓
PCB Layout Recommendations
Per Datasheet:
- Decoupling capacitors: Place 100nF ceramic capacitors as close as possible to VCCA and VCCB pins
- Ground plane: Use ground plane for GND pins (5, 13, 14)
- Trace routing: Keep A and B port traces short and matched length if possible
- Thermal: No special thermal considerations needed (low power device)
Design Verification
Our Design vs Datasheet:
| Requirement | Datasheet | Our Design | Status |
|---|---|---|---|
| VCCA voltage | 1.2V to 3.6V | 3.3V | ✓ |
| VCCB voltage | 1.65V to 5.5V | 5V | ✓ |
| VCCA ≤ VCCB | Required | 3.3V ≤ 5V | ✓ |
| OE connection | VCCA referenced | +3V3 (VCCA) | ✓ |
| Package | TSSOP-14 | TSSOP-14 | ✓ |
| Decoupling caps | 100nF on VCCA/VCCB | Missing | ⚠️ Should add |
Missing Components
Should Add:
- C14: 100nF ceramic capacitor from VCCA (Pin 12) to GND
- C15: 100nF ceramic capacitor from VCCB (Pin 11) to GND
Optional (for power-up safety):
- R7: 10kΩ pulldown resistor from OE (Pin 10) to GND (optional, not critical)
References
- Official Datasheet: TXB0104 Datasheet
- Package Information: TSSOP-14 (TXB0104PW)
- Application Note: See datasheet section 8 for typical applications