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CBM3232AS

OPERATION INSTRUCTION

Fig. 1 ESD Test Circuit for Human Body Model

The Contact Discharge Method applies the ESD current directly to the EUT. This method was

devised to reduce the unpredictability of the ESD arc. The discharge current rise time is constant

since the energy is directly transferred without the air-gap arc. In situations such as hand held

systems, the ESD charge can be directly discharged to the equipment from a person already

holding the equipment. The current is transferred on to the keypad or the serial port of the

equipment directly and then travels through the PCB and finally to the IC.

The circuit models in Figures 1 and 2 represent the typical ESD testing circuits used for these

methods. The CS is initially charged with the DC power supply when the first switch (SW1) is on.

Now that the capacitor is charged, the second switch (SW2) is on while SW1 switches off. The

voltage stored in the capacitor is then applied through RS, the current limiting resistor, onto the

device under test (DUT). In ESD tests, the SW2 switch is pulsed so that the device under test

receives a duration of voltage.

Fig. 2. ESD Test Circuit for IEC1000-4-2