SGS Thomson Microelectronics L4981A, L4981BD, L4981B, L4981AD Datasheet

	L4981A
	L4981B

POWER FACTOR CORRECTOR

CONTROL BOOST PWM UP TO 0.99P.F. LIMIT LINE CURRENT DISTORTION TO < 5% UNIVERSAL INPUT MAINS

FEED FORWARD LINE AND LOAD REGULATION

AVERAGE CURRENT MODE PWM FOR MINIMUM NOISE SENSITIVITY

HIGH CURRENT BIPOLAR AND DMOS TOTEM POLE OUTPUT

LOW START-UP CURRENT (0.3mA TYP.) UNDER VOLTAGE LOCKOUT WITH HYSTERESIS AND PROGRAMMABLE TURN ON THRESHOLD

OVERVOLTAGE, OVERCURRENT PROTECTION

PRECISE 2% ON CHIP REFERENCE EXTERNALLY AVAILABLE

SOFT START

DESCRIPTION

The L4981 I.C. provides the necessary features to achieve a very high power factor up to 0.99. Realized in BCD 60II technology this power factor corrector (PFC) pre-regulator contains all the con-

BLOCK DIAGRAM

MULTIPOWER BCD TECHNOLOGY

DIP20

SO20

ORDERING NUMBERS: L4981X (DIP20)

L4981XD (SO20)

trol functions for designing a high efficiency-mode power supply with sinusoidal line current consumption.

The L4981 can be easily used in systems with mains voltages between 85V to 265V without any line switch. This new PFC offers the possibility to work at fixed frequency (L4981A) or modulated frequency (L4981B) optimizing the size of the in-

September 1998

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L4981A - L4981B

put filter; both the operating frequency modes working with an average current mode PWM controller, maintaining sinusoidal line current without slope compensation.

Besides power MOSFET gate driver, precise voltage reference (externally available), error amplifier, undervoltage lockout, current sense and the

ABSOLUTE MAXIMUM RATINGS

soft start are included. To limit the number of the external components, the device integrates protections as overvoltage and overcurrent. The overcurrent level can be programmed using a simple resistor for L4981A. For a better precision and for L4981B an external divider must be used.

Symbol	Pin	Parameter			Value	Unit
VCC	19	Supply Voltage (ICC ≤50mA) (*)			selflimit	V
IGDRV	20	Gate driv. output peak current (t = 1μs)		SINK	2	Α
	.		SOURCE		1.5	A
VGDRV		Gate driv. output voltage t = 0.1μs			-1	V
		Voltages at pins 3, 14, 7, 6, 12, 15			-0.3 to 9	V
VVA-OUT	13	Error Amplifier Voltage			-0.3 to 8.5	V
IAC	4	AC Input Current			5	mA
		Voltages at pin 8, 9			-0.5 to 7	V
VCA-OUT	5	Current Amplifier Volt. (Isource = -20mA; Isink = 20mA)			-0.3 to 8.5	V
VROSC	17	Voltage at pin 17			-0.3 to 3	V
	11, 18	Voltage at pin 11, 18			-0.3 to 7	V
ICOSC	18	Input Sink Current			15	mA
IFREQ-MOD	16	Frequency Modulation Sink Current (L4981B)			5	mA
VSYNC	16	Sync. Voltage (L4981A)			-0.3 to 7	V
VIPK	2	Voltage at pin 2			-0.3 to 5.5	V
		Voltage at Pin 2 t = 1μs			-2	V
Ptot		Power Dissipation at Tamb = 70°C	(DIP20)		1	W
		Power Dissipation at Tamb = 70°C	(SO20)		0.6	W
Top		Operating Ambient Temperature			-40 to 125	°C
Tstg		StorageTemperature			-55 to 150	°C

(*) Maximum package power dissipation limits must be observed.

PIN CONNECTIONS (Top views)

L4981A	L4981B

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L4981A - L4981B

THERMAL DATA

Symbol			Parameter	DIP 20	SO 20	Unit
Rth j-amb		Thermal Resistance Junction-ambient		80	120	°C/W
PIN FUNCTIONS
N.		Name	Description
1		P-GND	Power ground.
2		IPK	L4981A peak current limiting. A current limitation is obtained using a single resistor connected
			between Pin 2 and the sense resistor. To have a better precision another resistor between Pin
			2 and a reference voltage (Pin 11) must be added.
			L4981B peak current limiting. A precise current limitation is obtained using two external
			resistor only. These resistors must be connected between the sense resistor, Pin 2 and the
			reference voltage.
3		OVP	Overvoltage protection. At this input are compared an internal precise 5.1V (typ) voltage
			reference with a sample of the boost output voltage obtained via a resistive voltage divider in
			order to limit the maximum output peak voltage.
4		IAC	Input for the AC current. An input current proportional to the rectified mains voltage generates,
			via a multiplier, the current reference for the current amplifier.
5	CA-OUT		Current amplifier output. An external RC network determinates the loop gain.
6		LFF	Load feedforward; this voltage input pin allows to modify the multiplier output current
			proportionally to the load, in order to give a faster response versus load transient. The best
			control is obtained working between 1.5V and 5.3V. If this function is not used, connect this pin
			to the voltage reference (pin = 11).
7		VRMS	Input for proportional RMS line voltage. the VRMS input compesates the line voltage changes.
			Connecting a low pass filter between the rectified line and the pin 7, a DC voltage proportional
			to the input line RMS voltage is obtained. The best control is reached using input voltage
			between 1.5V and 5.5V. If this function is not used connect this pin to the voltage reference
			(pin = 11).
8	MULT-OUT		Multiplier output. This pin common to the multiplier output and the current amplifier N.I. input is
			an high impedence input like ISENSE. The MULT-OUT pin must be taken not below -0.5V.
9		ISENSE	Current amplifier inverting input. Care must be taken to avoid this pin goes down -0.5V.
10		S-GND	Signal ground.
11		VREF	Output reference voltage (typ = 5.1V).Voltage refence at ± 2% of accuracy externally available,
			it's internally current limited and can deliver an output current up to 10mA.

12SS A capacitor connected to ground defines the soft start time. An internal current generator delivering 100μA (typ) charges the external capacitor defining the soft start time constant. An internal MOS discharge, the external soft start capacitor both in overvoltage and UVLO conditions.

13	VA-OUT	Error amplifier output, an RC network fixes the voltage loop gain characteristics.
14	VFEED	Voltage error amplifier inverting input. This feedback input is connected via a voltage divider to
		the boost output voltage.
15	P-UVLO	Programmable under voltage lock out threshold input. A voltage divider between supply
		voltage and GND can be connected in order to program the turn on threshold.
16	SYNC	This synchronization input/output pin is CMOS logic compatible. Operating as SYNC in, a
	(L4981A)	rectangular wave must be applied at this pin. Opearting as SYNC out, a rectangular clock
		pulse train is available to synchronize other devices.
	FREQ-MOD	Frequency modulation current input. An external resistor must be connected between pin 16
	(L4981B)	and the rectified line voltage in order to modulate the oscillator frequency. Connecting pin 16 to
		ground a fixed frequency imposed by ROSC and COSC is obtained.
17	ROSC	An external resistor connected to ground fixes the constant charging current of COSC.
18	COSC	An external capacitor connected to GND fixes the switching frequency.
19	VCC	Supply input voltage.
20	GDRV	Output gate driver. Bipolar and DMOS transistors totem pole output stage can deliver peak
		current in excess 1A useful to drive MOSFET or IGBT power stages.

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L4981A - L4981B

ELECTRICAL CHARACTERISTICS (Unless otherwise specified VCC = 18V, COSC = 1nF,

ROSC = 24KΩ, CSS = 1μF, VCA-OUT = 3.5V, VISENSE = 0V, VLFF = VREF, IAC = 100μA, VRMS = 1V, VFEED = GND, VIPK = 1V, VOVP = 1V, TJ = 25°C

Symbol	Prameter	Test Condition		Min.	Typ.	Max.	Unit
ERROR AMPLIFIER SECTION
VIO	Input Offset Voltage	±25°C < TJ < 85°C				±8	mV
IIB	Input Bias Current	VFEED = 0V		-500	-50	500	nA
	Open Loop Gain			70	100		dB
V13H	Output High voltage	VFEED = 4.7V		5.5	6.5	7.5	V
		IVA-OUT = -0.5mA
V13L	Output Low Voltage	VFEED = 5.5V			0.4	1	V
		IVA-OUT = 0.5mA
-I13	Output Source Current	VFEED = 4.7V; VVA-OUT = 3.5V		2	10		mA
I13	Output Sink Current	VFEED = 5.5V; VVA-OUT = 3.5V		4	20		mA
REFERENCE SECTION
Vref	Reference Output Voltage	±25°C < TJ < 85°C		4.97	5.1	5.23	V
		Tj = 25°C	Iref = 0	5.01	5.1	5.19	V
Vref	Load Regulation	1mA ≤ Iref	≤ 10mA		3	15	mV
		±25°C < TJ < 85°C
Vref	Line Regulation	12V ≤ VCC ≤ 19V			3	10	mV
		±25°C < TJ < 85°C
Iref sc	Short Circuit Current	Vref = 0V		20	30	50	mA
OSCILLATOR SECTION
fosc	Initial Accuracy	Tj = 25°C		85	100	115	KHz
	Frequency Stability	12V ≤ VCC ≤ 19V		80	100	120	KHz
		±25°C < TJ < 85°C
Vsvp	Ramp Valley to Peak			4.7	5	5.3	V
I18C	Charge Current	VCOSC = 3.5V		0.45	0.55	0.65	mA
I18D	Discharge Current	VCOSC = 3.5V			11.5		mA
V18	Ramp Valley Voltage			0.9	1.15	1.4	V
SYNC SECTION (Only for L4981A)
tW	Output Pulse Width	50% Amplitude		0.3	0.8		μs
I16	Sink Current with Low Output	VSYNC = 0.4V		0.4	0.8		mA
	Voltage	VCOSC = 0V
-I16	Source Current with High Output	VSYNC = 4.5V		1	6		mA
	Voltage	VCOSC = 6.7V
V16L	Low Input Voltage					0.9	V
V16H	High Input Voltage			3.5			V
td	Pulse for Synchronization			800			ns

FREQUENCY MODULATION FUNCTION (Only for L4981B)

f18max	Maximum Oscillation Frequency	VFREQ-MOD = 0V (Pin 16) Ifreq = 0	85	100	115	KHz
f18min	Minimum Oscillator Frequency	IFREQ-MOD = 360μA (Pin 16)		74		KHz
		VVRMS = 4V (Pin 7)
		IFREQ-MOD = 180μA (Pin 16)		76		KHz
		VVRMS = 2V (Pin 7)
SOFT START SECTION
ISS	Soft Start Source Current	VSS = 3V	60	100	140	μA
V12sat	Output Saturation Voltage	V3 = 6V, ISS = 2mA		0.1	0.25	V

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L4981A - L4981B

ELECTRICAL CHARACTERISTICS (continued)

Symbol	Parameter		Test Condition		Min.	Typ.	Max.	Unit
SUPPLY VOLTAGE
VCC	Operating Supply Voltage						19.5	V
OVER VOLTAGE PROTECTION COMPARATOR
Vthr	Rising Threshold Voltage				Vref	5.1	Vref	V
					-20mV		+20mV
V3Hys	Hysteresis				180	250	320	mV
I3	Input Bias Current					0.05	1	μA
td	Propagation delay to output	VOVP = Vthr +100mV				1	2	μs
OVER CURRENT PROTECTION COMPARATOR
Vth	Threshold Voltage						±30	mV
td	Propagation delay to Output	VOCP = Vthr -0.2V				0.4	0.9	μs
Iipk	Current Source Generator	VIPK = -0.1V		only for L4981A	65	85	105	μA
IL	Leakage Current	VIPK = -0.1V		only for L4981B			5	μA
CURRENT AMPLIFIER SECTION
Voffset	Input Offset Voltage	VMULT OUT = VSENSE = 3.5V					±2	mV
I9bias	Input Bias Current	VSENSE = 0V			-500	50	500	nA
	Open Loop Gain	1.1V ≤	VCA OUT ≤ 6V		70	100		dB
SVR	Supply Voltage Rejection	12V ≤	VCC ≤ 19V		68	90		dB
		VMULT OUT = 3.5V VSENSE = 3.5V
V5H	Output High Voltage	VMULT OUT = 200mV			6.2			V
		ICA OUT = -0.5mA, VIAC = 0V
V5L	Output Low Voltage	VMULT OUT = -200mV					0.9	V
		ICA OUT = 0.5mA, VIAC = 0V
-I5	Output Source Current	VMULT OUT = 200mV,			2	10		mA
I5	Output Sink Current	VIAC = 0V, VCA-OUT = 3.5V			2	10		mA
OUTPUT SECTION
V20L	Output Voltage Low	ISINK = 250mA				0.5	0.8	V
V20H	Output Voltage High	ISOURCE = 250mA			11.5	12.5		V
		VCC = 15V
tr	Output Voltage Rise Time	COUT = 1nF				50	150	ns
tf	Output Voltage Fall Time	COUT = 1nF				30	100	ns
VGDRV	Voltage Clamp	ISOURCE = 0mA			13	16	19	V
TOTAL STANDBY CURRENT SECTION
I19start	Supply Current before start up	VCC = 14V				0.3	0.5	mA
I19on	Supply Current after turn on	VIAC = 0V, VCOSC = 0,				8	12	mA
		Pin17 = Open
I19	Operating Supply Current	Pin20 = 1nF				12	16	mA
VCC	Zener Voltage	(*)			20	25	30	V
UNDER VOLTAGE LOCKOUT SECTION

Vth ON

Vth OFF

Turn on Threshold	14.5	15.5	16.5	V
Turn off Threshold	9	10	11	V
Programmable Turn-on Threshold Pin 15 to VCC = 220K	10.6	12	13.4	V
Pin15 to GND = 33K

LOAD FEED FORWARD
ILFF	Bias Current	V6 = 1.6V	70	140	μA
		V6 = 5.3V	200	300	μA
VI	Input Voltage Range		1.6	5.3	V

(*) Maximum package power dissipation limits must be observed.

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L4981A - L4981B

ELECTRICAL CHARACTERISTICS (continued)

Symbol	Prameter	Test Condition	Min.	Typ.	Max.	Unit
MULTIPLIER SECTION
	Multipler Output Current	VVA-OUT = 4V, VRMS = 2V,	20	35	52	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 50μA, COSC = 0V
		VVA-OUT = 4V, VRMS = 2V,	100	135	170	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 200μA, COSC = 0V
		VVA-OUT = 2V, VRMS = 2V,	10	20	30	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 100μA, COSC = 0V
		VVA-OUT = 2V, VRMS = 4V,	2	5.5	11	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 100μA, COSC = 0V
		VVA-OUT = 4V, VRMS = 4V,	10	22	34	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 100μA, COSC = 0V
		VVA-OUT = 4V, VRMS = 2V,	20	37	54	μA
		VMULTOUT = 0, VLFF = 2.5V
		COSC = 0V, IAC = 200μA
		VVA-OUT = 4V, VRMS = 4V	20	39	54	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 200μA, COSC = 0V
		VVA-OUT = 2V, VRMS = 4V,	-2	0	2	μA
		VMULTOUT = 0, VLFF = 5.1V
		IAC = 0, COSC = 0V
K	Multiplier Gain			0.37

(VVA−OUT − 1.28) (0.8 VLFF − 1.28)
IMULT−OUT = K IAC	(VVRMS)2
(V	−	− 1.28)
VA OUT			K1
if VLFF = VREF; IMULT−OUT = IAC	(VVRMS)2
where: K1 = 1V
Figure 1: MULTI-OUT vs. IAC (VRMS = 1.7V;				Figure 2: MULTI-OUT vs. IAC (VRMS = 2.2V;
VLFFD = 5.1V)				VLFFD = 5.1V)

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