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ESDA25L has been replaced by USBLC6-2SC6 in v1.1 design.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
│
GNDApplication 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 |