TEA1501 View Datasheet(PDF) - Philips Electronics

Part Name

Description

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TEA1501

GreenChip SMPS controller IC

Philips Electronics 

Philips Semiconductors

TEA1501

GreenChip SMPS controller IC

IAUX

operation

12 V

UVLO

16 V

Vstart

20 V

VAUX(max)

VAUX

Istart

start-up

mgm824

Fig 5. IAUX as a function of VAUX

7.3.3 Start-up current source

The start-up sequence is carried out using an accurate start-up current source. The

start-up current flows from the DRAIN pin to the AUX pin via the start-up current source

and charges the AUX capacitor. When AUX reaches the start-up threshold the start-up

current is switched off and the flyback converter starts operating and the output voltage

rises. The AUX capacitor must be capable of supplying the entire supply current (IAUX(low))

until the output voltage is in regulation. From that moment the AUX capacitor is charged

by the flyback converter via the auxiliary winding.

7.3.4 Reference block

The reference block contains a band gap circuit which determines all the accurate and

temperature independent reference voltages and currents. It defines the voltage detection

level for the primary current comparator and it defines the voltage at the REF pin. The

value of the reference resistor determines the burst frequency, the switching frequency

and the leading edge blanking time.

7.3.5 Temperature protection

The temperature protection circuit senses the chip temperature using a proportional to

absolute temperature voltage (Vptat) generated in the reference block. If the chip

temperature exceeds 140 °C the power switch and the start-up current source are

disabled. When the chip cools down below 100 °C, the start-up circuit is enabled again.

7.3.6 Switch oscillator

The switch oscillator determines the switching frequency and the maximum on-time of the

power switch. The maximum on-time is set at 66 % of the switching period. The switching

frequency is determined by the reference resistor at the REF pin and an internal capacitor.

The switching frequency can be adjusted in a range from 20 kHz to 50 kHz, thus above

the audible spectrum.

7.3.7 Burst oscillator

The burst oscillator generates a triangular wave signal for determination of the burst

frequency. The burst frequency is determined accurately and temperature independent by

the externally connected reference resistor RREF and burst capacitor CBURST.

TEA1501_2

Product data sheet

Rev. 02 — 31 March 2006

© Koninklijke Philips Electronics N.V. 2006. All rights reserved.

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