GreenChip X capacitor discharge IC
7. Functional description
The TEA1708 incorporates a timer and a zero-crossing mains voltage detector. If a
positive or negative voltage above the threshold zero-crossing mains voltage (20 V) is
applied between the high-voltage pins, the timer charges the external capacitor on the
TMR1 and TMR2 pins. If the voltage between the TMR1 and TMR2 pins reaches 1.2 V, a
discharge current is activated. If the voltage applied between the high-voltage pins, is
below the threshold zero-crossing mains voltage, the external capacitor is discharged and
the discharging stops. The discharge current is internally limited.
When an AC mains voltage is applied, the timer capacitor is charged between the mains
zero crossings and discharged during the mains zero crossings. When the AC mains is
disconnected and a high voltage remains on the X capacitor, the timer charges the
external capacitor above its discharge activation threshold voltage point (1.2 V), switching
on the internally limited discharge current of the external X capacitor.
Fig 3. Functional behavior
To protect the IC during mains surges, a high voltage clamping circuit is integrated. The
clamping circuit is activated for > 500 V positive and negative voltages. The high-voltage
pins HV1 and HV2 are fully symmetrical.
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 25 September 2013
© NXP B.V. 2013. All rights reserved.
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