ESDA25L - TVS Diode (Legacy)
Not Used in Current Design
ESDA25L has been replaced by USBLC6-2SC6 in v1.1 design.
Reason: ESDA25L's clamping voltage (~44V) is too high for CC line protection. USBLC6-2SC6 clamps at ~17V and includes VBUS protection.
TVS diode for high-voltage ESD and overvoltage protection.
Overview
The ESDA25L is a TVS (Transient Voltage Suppressor) diode designed for ESD protection on USB Type-C CC (Configuration Channel) lines. It protects the STUSB4500 CC pins from electrostatic discharge and voltage transients.
Key Specifications
| Parameter | Value | Notes |
|---|---|---|
| JLCPCB Part Number | C343997 | |
| Manufacturer Part Number | ESDA25L | STMicroelectronics |
| Package | SOT-23 | 3-pin surface-mount |
| Stock Availability | 4,584 | Good availability |
| Unit Price | ~$0.15 | |
| Working Voltage | 25V | CC lines up to 22V |
| Breakdown Voltage | 27.6V min | |
| Clamping Voltage | 40V @ 1A | |
| Peak Pulse Current | 3A | 8/20µs waveform |
| Capacitance | 3pF typ | Low impact on CC signals |
| ESD Rating | 15kV (HBM) | IEC 61000-4-2 |
Pin Configuration
ESDA25L (SOT-23)
Top View
┌───────────────┐
│ ┌─────┐ │
│ │ │ │
K1 │1 │ │ 3│ K2
│ │ │ │
│ └─────┘ │
│ 2 │
└───────┬───────┘
A (Common Anode)
Pin 1: Cathode 1 (K1) - CC1
Pin 2: Anode (A) - GND
Pin 3: Cathode 2 (K2) - CC2
Internal Structure:
CC1 ───┤◄├───┬───┤►├─── CC2
│
GND
Application in STUSB4500 Circuit
USB-C Connector STUSB4500
┌──────────────┐ ┌──────────────┐
│ │ │ │
│ CC1 ───────┼────────┬───┤ CC1 (pin 2) │
│ │ │ │ │
│ CC2 ───────┼────┬───┼───┤ CC2 (pin 3) │
│ │ │ │ │ │
└──────────────┘ │ │ └──────────────┘
│ │
│ │ ESDA25L
│ │ ┌────────┐
│ └───┤ K1 (1) │
│ │ │
│ │ A (2) ├─── GND
│ │ │
└───────┤ K2 (3) │
└────────┘
Why CC Protection is Important
| Threat | Source | Protection |
|---|---|---|
| ESD | Cable insertion/removal | 15kV HBM rating |
| Short to VBUS | Faulty cable/adapter | 25V working voltage |
| Transients | Hot-plug events | Fast clamping |
The STUSB4500 has internal CC protection up to 22V, but external TVS provides additional margin and faster response.
Design Considerations
Placement
- Place ESDA25L as close as possible to USB-C connector
- Short traces to GND for effective clamping
- Before any series resistors on CC lines
Capacitance Impact
- 3pF typical capacitance is acceptable for CC communication
- USB PD CC signaling tolerates up to 200pF
Alternative Parts
| Part | Package | Voltage | Capacitance | Notes |
|---|---|---|---|---|
| ESDA25L | SOT-23 | 25V | 3pF | Recommended |
| ESDA25W | SOT-353 | 25V | 1.5pF | Lower capacitance |
| ESDA25SC6 | SOT-23-6 | 25V | 1.5pF | 4-channel version |