Philips TEA1039 Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TEA1039

Control circuit for switched-mode power supply

Product speciﬁcation File under Integrated Circuits, IC02

August 1982

Philips Semiconductors Product speciﬁcation

Control circuit for switched-mode power supply TEA1039

GENERAL DESCRIPTION

The TEA1039 is a bipolar integrated circuit intended for the control of a switched-mode power supply. Together with an external error amplifier and a voltage regulator (e.g. a regulator diode) it forms a complete control system. The circuit is capable of directly driving the SMPS power transistor in small SMPS systems.

It has the following features:

• Suited for frequency and duty factor regulation.

• Suited for flyback converters and forward converters.

• Wide frequency range.

• Adjustable input sensitivity.

• Adjustable minimum frequency or maximum duty factor limit.

• Adjustable overcurrent protection limit.

• Supply voltage out-of-range protection.

• Slow-start facility.

QUICK REFERENCE DATA

Supply voltage V Supply current I Output pulse repetition frequency range f Output current LOW I Operating ambient temperature range T

PACKAGE OUTLINE

9-lead SIL; plastic (SOT-110B); SOT110-1; 1996 November 18.

CC o OL

amb

nom. 14 V max. 13 mA

1 Hz to 100 kHz

max. 1 A

−25 to +125 °C

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Philips Semiconductors Product speciﬁcation

Control circuit for switched-mode power supply

TEA1039

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Fig.1 Block diagram.

Philips Semiconductors Product speciﬁcation

Control circuit for switched-mode power supply TEA1039

PINNING

1 CM overcurrent protection input 2 LIM limit setting input 3 FB feedback input 4 RX external resistor connection 5 CX external capacitor connection 6 M mode input 7V 8 Q output 9V

common

positive supply connection

Fig.2 Pinning diagram.

FUNCTIONAL DESCRIPTION

The TEA1039 produces pulses to drive the transistor in a switched-mode power supply. These pulses may be varied either in frequency (frequency regulation mode) or in width (duty factor regulation mode).

The usual arrangement is such that the transistor in the SMPS is ON when the output of the TEA1039 is HIGH, i.e. when the open-collector output transistor is OFF. The duty factor of the SMPS is the time that the output of the TEA1039 is HIGH divided by the pulse repetition time.

Supply V

(pin 9)

The circuit is usually supplied from the SMPS that it regulates. It may be supplied either from its primary d.c. voltage or from its output voltage. In the latter case an auxiliary starting supply is necessary.

The circuit has an internal V

out-of-range protection. In

the frequency regulation mode the oscillator is stopped; in the duty factor regulation mode the duty factor is made zero. When the supply voltage returns within its range, the circuit is started with the slow-start procedure.

When the circuit is supplied from the SMPS itself, the out-of-range protection also provides an effective protection against any interruption in the feedback loop.

Mode input M (pin 6) The circuit works in the frequency regulation mode when

the mode input M is connected to ground (V

, pin 7). In

this mode the circuit produces output pulses of a constant width but with a variable pulse repetition time.

The circuit works in the duty factor regulation mode when the mode input M is left open. In this mode the circuit produces output pulses with a variable width but with a constant pulse repetition time.

Oscillator resistor and capacitor connections RX and CX (pins 4 and 5)

The output pulse repetition frequency is set by an oscillator whose frequency is determined by an external capacitor C5 connected between the CX connection (pin 5) and ground (V

, pin 7), and an external resistor R4connected

between the RX connection (pin 4) and ground. The capacitor C5 is charged by an internal current source, whose current level is determined by the resistor R4. In the frequency regulation mode these two external

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Philips Semiconductors Product speciﬁcation

Control circuit for switched-mode power supply TEA1039

components determine the minimum frequency; in the duty factor regulation mode they determine the working frequency (see Fig.4). The output pulse repetition frequency varies less than 1% with the supply voltage over the supply voltage range.

In the frequency regulation mode the output is LOW from the start of the cycle until the voltage on the capacitor reaches 2 V. The capacitor is further charged until its voltage reaches the voltage on either the feedback input FB or the limit setting input LIM, provided it has exceeded 2,2 V. As soon as the capacitor voltage reaches 5,9 V the capacitor is discharged rapidly to 1,3 V and a new cycle is initiated (see Figs 5 and 6).

For voltages on the FB and LIM inputs lower than 2,2 V, the capacitor is charged until this voltage is reached; this sets an internal maximum frequency limit.

In the duty factor regulation mode the capacitor is charged from 1,3 V to 5,9 V and discharged again at a constant rate. The output is HIGH until the voltage on the capacitor exceeds the voltage on the feedback input FB; it becomes HIGH again after discharge of the capacitor (see Figs 7 and 8). An internal maximum limit is set to the duty factor of the SMPS by the discharging time of the capacitor.

Feedback input FB (pin 3) The feedback input compares the input current with an

internal current source whose current level is set by the external resistor R4. In the frequency regulation mode, the higher the voltage on the FB input, the longer the external capacitor C5 is charged, and the lower the frequency will be. In the duty factor regulation mode external capacitor C5 is charged and discharged at a constant rate, the voltage on the FB input now determines the moment that the output will become LOW. The higher the voltage on the FB input, the longer the output remains HIGH, and the higher the duty factor of the SMPS.

Limit setting input LIM (pin 2) In the frequency regulation mode this input sets the

minimum frequency, in the duty factor regulation mode it sets the maximum duty factor of the SMPS. The limit is set by an external resistor R2 connected from the LIM input to ground (pin 7) and by an internal current source, whose current level is determined by external resistor R4.

A slow-start procedure is obtained by connecting a capacitor between the LIM input and ground. In the frequency regulation mode the frequency slowly decreases from f factor regulation mode the duty factor slowly increases from zero to the working duty factor.

Overcurrent protection input CM (pin 1) A voltage on the CM input exceeding 0,37 V causes an

immediate termination of the output pulse. In the duty factor regulation mode the circuit starts again with the slow-start procedure.

Output Q (pin 8) The output is an open-collector n-p-n transistor, only

capable of sinking current. It requires an external resistor to drive a n-p-n transistor in the SMPS (see Figs 9 and 10).

The output is protected by two diodes, one to ground and one to the supply.

At high output currents the dissipation in the output transistor may necessitate a heatsink. See the power derating curve (Fig.3).

to the working frequency. In the duty

max

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