TEA1738T Ver la hoja de datos (PDF) - NXP Semiconductors.

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Fabricante

TEA1738T

GreenChip SMPS control IC

NXP Semiconductors. 

NXP Semiconductors

TEA1738T; TEA1738LT

GreenChip SMPS control IC

VCC

ISENSE

VINSENSE

PROTECT

OPTIMER

soft start

Vstartup

Vth(UVLO)

soft start

Vstart(VINSENSE)

Vdet(L)(VINSENSE)

Vdet(H)(PROTECT)

Vdet(L)(PROTECT)

4.5 V

1.2 V

VO

charging VCC

capacitor

starting

converter

normal

operation

(power-down)

protection

restart

001aan170

Fig 4. Start-up sequence, normal operation and restart sequence

When the voltage on pin VCC drops below the Vth(UVLO) level during normal operation, the

controller stops switching and the TEA1738T enters Restart mode. In Restart mode the

driver output is disabled and the VCC pin voltage is recharged via resistor R3 to the

rectified mains voltage. For the TEA1738LT a VCC undervoltage, which does not occur

during a start-up event, latches the IC in an off-state.

7.3 Supply management

All internal reference voltages are derived from a temperature compensated on-chip band

gap circuit. Internal reference currents are derived from a trimmed and temperature

compensated current reference circuit.

7.4 OverVoltage Protection (VCC pin)

An OVP circuit is connected to the VCC pin. After 8 consecutive OVP cycles the IC

triggers the latched protection. When VCC drops below the Vth(OVP) voltage before count=8

is reached, the counter is reset to zero.

If a lower overvoltage protection level is needed, a Zener diode can be connected

between the VCC pin and the PROTECT pin.

7.5 Input voltage detection (VINSENSE pin)

In a typical application the mains input voltage can be detected by the VINSENSE pin.

Switching does not take place until the voltage on VINSENSE has reached the

Vstart(VINSENSE) voltage (0.94 V typical).

When during operation the VINSENSE voltage drops below Vdet(L)(VINSENSE)

(0.72 V typical), the converter stops switching and performs a restart.

An internal clamp of 5.2 V (typical) protects this pin from excessive voltages.

TEA1738T_TEA1738LT

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 2 — 14 January 2011

© NXP B.V. 2011. All rights reserved.

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