Philips TEA1620P Technical data

TEA1620P

STARplugTM

Rev. 01 — 17 March 2004	Product data sheet

1. General description

The TEA1620P is a Switched Mode Power Supply (SMPS) controller IC that operates directly from the rectiﬁed universal mains. It is implemented in the high voltage EZ-HV™ SOI process, combined with a low voltage BICMOS process.

The device includes a high voltage power switch and a circuit for start-up directly from the rectiﬁed mains voltage. A dedicated circuit for valley switching is built in, which makes a very efﬁcient slim-line electronic power-plug concept possible.

In its most basic version of application, the TEA1620P acts as a voltage source. Here, no additional secondary electronics are required. A combined voltage and current source can be realized with minimum costs for external components. Implementation of the TEA1620P renders an efﬁcient and low cost power supply system.

2. Features

■Designed for general purpose supplies

■Integrated power switch: 48 Ω and 650 V

■Operates from universal AC mains supplies: 80 V to 276 V

■Adjustable frequency for ﬂexible design

■RC oscillator for load insensitive regulation loop constant

■Valley switching for minimum switch-on loss

■Frequency reduction at low power output for low standby power: <100 mW

■Adjustable overcurrent protection

■Undervoltage protection

■Temperature protection

■Short winding protection

■Safe restart mode for system fault conditions

■Simple application with both primary and secondary (opto) feedback

■Available in 8-pin DIP package.

3.Applications

■Chargers

■Adapters

■TV and monitor standby supplies

■PC peripherals.

Philips Semiconductors			TEA1620P
			STARplugTM

4. Quick reference data

Table 1:	Quick reference data
Symbol	Parameter	Conditions	Min	Typ	Max	Unit
VCC(max)	maximum supply voltage		-	-	40	V
VDRAIN(max)	maximum voltage at pin	Tj > 0 °C	-	-	650	V
	DRAIN

IDRAIN	supply current drawn from	no auxiliary supply	-	0.5	-	mA
	pin DRAIN

RDSon	drain-source on-state	ISOURCE = −0.06 A
	resistance
	resistance	Tj = 25 °C	-	48	55.2	Ω
		Tj = 25 °C	-	48	55.2	Ω
		Tj = 100 °C	-	68	78.2	Ω
fosc	oscillator frequency range		10	-	200	kHz
Tamb	ambient temperature		−20	-	+85	°C

5. Ordering information

Table 2: Ordering information

Type number	Package
	Name	Description	Version
TEA1620P	DIP8	plastic dual in-line package; 8 leads (300 mil)	SOT97-1

9397 750 12577

Product data sheet

Rev. 01 — 17 March 2004

2 of 16

Philips Semiconductors			TEA1620P
			STARplugTM

6. Block diagram

VCC	1		SUPPLY	8
VCC			SUPPLY	DRAIN
			TEA1620P	VALLEY
			TEA1620P
	2		LOGIC	7
GND	2			7
GND				n.c.
				100 mV
			PWM
	stop
RC	3		THERMAL	6
RC	OSCILLATOR		THERMAL	SOURCE
			SHUTDOWN
	low frequency		PROTECTION
			LOGIC
	f		POWER-UP	blank
			RESET	blank
			RESET
	1.8	U
			overcurrent
	2.5 V			0.5 V
REG	4			5
REG	10x			AUX
			short winding
				0.75 V
				col006

Fig 1. Block diagram.

7.Pinning information

7.1Pinning

VCC	1	8	DRAIN
GND	2	7	n.c.
RC	3	TEA1620P	SOURCE
RC	3	6	SOURCE
REG	4	5	AUX
		001aaa308

Fig 2. Pin conﬁguration.

9397 750 12577

Product data sheet

Rev. 01 — 17 March 2004

3 of 16

Philips Semiconductors				TEA1620P
				STARplugTM
	7.2 Pin description
		Table 3:	Pin description

		Symbol	Pin	Description
		VCC	1	supply voltage
		GND	2	ground

		RC	3	frequency setting

		REG	4	regulation input

		AUX	5	input for voltage from auxiliary winding for timing (demagnetization)

		SOURCE	6	source of internal MOS switch

		n.c.	7	not connected

		DRAIN	8	drain of internal MOS switch; input for start-up current and valley sensing

8. Functional description

The TEA1620P is the heart of a compact ﬂyback converter, with the IC placed at the primary side. The auxiliary winding of the transformer can be used for indirect feedback to control the isolated output. This additional winding also powers the IC. A more accurate control of the output voltage and/or current can be implemented with an additional secondary sensing circuit and optocoupler feedback.

The TEA1620P uses voltage mode control. The frequency is determined by the maximum transformer demagnetizing time and the time of the oscillator. In the ﬁrst case, the converter operates in the Self Oscillating Power Supply (SOPS) mode. In the latter case, it operates at a constant frequency, which can be adjusted with external components RRC and CRC. This mode is called Pulse Width Modulation (PWM). Furthermore, a primary stroke is started only in a valley of the secondary ringing. This valley switching principle minimizes capacitive switch-on losses.

8.1 Start-up and undervoltage lock-out

Initially, the IC is self supplying from the rectiﬁed mains voltage. The IC starts switching as

soon as the voltage on pin VCC passes the VCC(start) level. The supply is taken over by the auxiliary winding of the transformer as soon as VCC is high enough and the supply from

the line is stopped for high efﬁciency operation.

As soon as the voltage on pin VCC drops below the VCC(stop) level, the IC stops switching and restarts from the rectiﬁed mains voltage.

8.2 Oscillator

The frequency of the oscillator is set by the external resistor and capacitor on pin RC. The

external capacitor is charged rapidly to the VRC(max) level and, starting from a new primary stroke, it discharges to the VRC(min) level. Because the discharge is exponential, the relative sensitivity of the duty factor to the regulation voltage at low duty factor is almost

equal to the sensitivity at high duty factors. This results in a more constant gain over the duty factor range compared to PWM systems with a linear sawtooth oscillator. Stable operation at low duty factors is easily realized. For high efﬁciency, the frequency is reduced as soon as the duty factor drops below a certain value. This is accomplished by increasing the oscillator charge time.

9397 750 12577

Product data sheet

Rev. 01 — 17 March 2004

4 of 16

Philips Semiconductors TEA1620P

STARplugTM

To ensure that the capacitor can be charged within the charge time, the value of the oscillator capacitor should be limited to approximately 1 nF.

8.3 Duty factor control

The duty factor is controlled by the internal regulation voltage and the oscillator signal on pin RC. The internal regulation voltage is equal to the external regulation voltage (minus 2.5 V) multiplied by the gain of the error ampliﬁer (typical 20 dB or 10 ×).

The minimum duty factor of the switched mode power supply is 0 %. The maximum duty factor is set to 75 % (typical value at 100 kHz oscillation frequency).

8.4 Valley switching

A new cycle is started at the primary stroke when the switch is switched on (see Figure 3). After a certain time (determined by the RC oscillator voltage and the internal regulation level), the switch is turned off and the secondary stroke starts. The internal regulation

level is determined by the voltage on pin REG. After the secondary stroke, the drain

1 voltage shows an oscillation with a frequency of approximately ------------------------------

2π × L pC p

Where:

Lp is the primary self inductance on the drain node

Cp is the parasitic capacitance on the drain node.

As soon as the oscillator voltage is high again and the secondary stroke has ended, the circuit waits for a low drain voltage before starting a new primary stroke.

The primary stroke starts some time before the actual valley at low ringing frequencies, and some time after the actual valley at high ringing frequencies. Figure 4 shows a typical curve for a reﬂected voltage N × Vo of 80 V. This voltage is the output voltage Vo (see Figure 5) transferred to the primary side of the transformer with the factor N (determined by the turns ratio of the transformer). Figure 4 shows that the system switches exactly at minimum drain voltage for ringing frequencies of 480 kHz, thus reducing the switch-on losses to a minimum. At 200 kHz, the next primary stroke is started at 33° before the valley. The switch-on losses are still reduced signiﬁcantly.

9397 750 12577

Product data sheet

Rev. 01 — 17 March 2004

5 of 16

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