ESD9B3.3ST5G

The ESD9B3.3ST5G is a bidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed to protect voltage-sensitive components from electrostatic discharge (ESD) events. It features a working peak reverse voltage (VRWM) of 3.3 V, breakdown voltage (VBR) of 5.0 V minimum at 1 mA test current, and clamping voltage of 10.5 V maximum at IPP = 1 A (8/20 μs waveform).

The device provides IEC 61000-4-2 Level 4 ESD protection rated at ±18 kV for both contact and air gap discharge. It has a capacitance of 15 pF at 1 MHz, leakage current of 100 nA maximum at VRWM, and response time of less than 1 ns. The ESD9B3.3ST5G is AEC-Q101 qualified and PPAP capable, making it suitable for automotive applications.

Packaged in the ultra-small SOD-923 (Case 514AB) with body dimensions of 1.0 x 0.6 x 0.4 mm, it is ideal for space-constrained portable applications such as cellular phones, MP3 players, and digital cameras. The device is Pb-free with matte tin lead finish, MSL-1 rated, and operates over a junction temperature range of -55°C to +150°C. Tape and reel packaging of 8000 units per reel.

The ESD9B3.3ST5G operates as a bidirectional TVS diode, providing ESD protection by clamping transient voltage excursions to safe levels.

Normal Operation: When the protected line voltage is within the working range (0 to ±3.3 V), the TVS diode is in its high-impedance state. The device presents minimal loading to the circuit with a leakage current of only 100 nA maximum and a junction capacitance of 15 pF, ensuring signal integrity on the protected line.

ESD Event: When an electrostatic discharge event occurs, the voltage on the protected line rises above the breakdown voltage (VBR ≥ 5.0 V). The TVS diode avalanches, transitioning from high impedance to low impedance within less than 1 nanosecond. The ESD current is diverted through the diode to ground, clamping the voltage at the protected node to 10.5 V maximum (at IPP = 1 A). This fast response and low clamping voltage prevent damage to downstream ICs.

Bidirectional Protection: The bidirectional structure contains two back-to-back Zener junctions, allowing the device to clamp both positive and negative transient events. This is essential for protecting AC-coupled or bidirectional signal lines where voltage can swing in either polarity.

Surge Current Handling: For IEC 61000-4-5 surge events (8/20 μs), the device can handle up to 2 A peak pulse current (IPP = 2 A) with a clamping voltage of 11.5 V. The peak pulse power dissipation is rated at 35 W (8/20 μs).

Thermal Behavior: Under transient events, the heat generated in the avalanche junction is dissipated through the lead frame and PCB. The thermal resistance (RθJA) is 400°C/W on FR-5 board. The device is designed to handle repeated transient events within its rated specifications without degradation.