SGS Thomson Microelectronics L4981A, L4981BD, L4981B, L4981AD Datasheet

L4981A



CONTROLBOOSTPWM UP TO0.99P.F.
LIMITLINECURRENT DISTORTIONTO< 5%
UNIVERSALINPUT MAINS
FEED FORWARD LINE AND LOAD REGULA-

TION
AVERAGE CURRENT MODE PWM FOR

MINIMUMNOISE SENSITIVITY
HIGH CURRENT BIPOLAR AND DMOS TO-

TEM POLEOUTPUT
LOW START-UP CURRENT (0.3mATYP.)
UNDER VOLTAGE LOCKOUT WITH HYS-

TERESIS AND PROGRAMMABLE TURN ON
THRESHOLD

OVERVOLTAGE, OVERCURRENT PROTEC­TION

PRECISE 2% ON CHIP REFERENCE EX­TERNALLYAVAILABLE

SOFTSTART

DESCRIPTION

The L4981 I.C. provides the necessary features
to achievea veryhigh power factor up to 0.99.
Realized in BCD 60II technology this power factor
corrector (PFC) pre-regulatorcontains all the con-

L4981B

POWER FACTOR CORRECTOR

MULTIPOWER BCD TECHNOLOGY

DIP20 SO20

ORDERING NUMBERS: L4981X (DIP20)

L4981XD (SO20)

trol functions for designing a highefficiency-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-

BLOCK DIAGRAM

September 1998

1/17

L4981A - L4981B

put filter; both the operating frequency modes
working with an averagecurrent mode PWM con­troller, maintaining sinusoidal line current without
slope compensation.
Besides power MOSFET gate driver, precise volt­age reference (externally available), error ampli-

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.

fier, undervoltage lockout, current sense and the

ABSOLUTE MAXIMUM RATINGS

Symbol Pin Parameter Value Unit

V

I

GDRV

CC

19 Supply Voltage (I
20 Gate driv. output peak current (t = 1µs) SINK 2

. SOURCE 1.5 A

V

GDRV

Gate driv. output voltage t = 0.1µs-1V
Voltages at pins 3, 14, 7, 6, 12, 15 -0.3 to 9 V

V

VA-OUT

AC 4 AC Input Current 5 mA

I

13 Error AmplifierVoltage -0.3 to 8.5 V

Voltages at pin 8, 9 -0.5 to 7 V

CA-OUT 5 Current Amplifier Volt. (Isource = -20mA; Isink = 20mA) -0.3 to 8.5 V

V

V

ROSC

17 Voltage at pin 17 -0.3 to 3 V

11, 18 Voltage at pin 11, 18 -0.3 to 7 V

I

COSC

I

FREQ-MOD

V

SYNC

V

IPK

18 Input Sink Current 15 mA
16 Frequency Modulation Sink Current (L4981B) 5 mA
16 Sync. Voltage (L4981A) -0.3 to 7 V

2 Voltage at pin 2

Voltage at Pin 2 t = 1µs

P

tot Power Dissipation at T

Power Dissipation at T

T

op

T

stg

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

Operating Ambient Temperature -40 to 125 °C
StorageTemperature -55 to 150 °C

50mA) (*) selflimit V

CC ≤

-0.3 to 5.5

-2

=70°C (DIP20) 1 W

amb

=70°C (SO20) 0.6 W

amb

Α

V
V

PIN CONNECTIONS (Top views)

L4981A

2/17

L4981B

L4981A - L4981B

THERMAL DATA

Symbol Parameter DIP 20 SO 20 Unit

R

th j-amb

PIN FUNCTIONS

N. Name Description

1 P-GND Power ground.
2 IPK L4981A peak current limiting. A current limitation is obtained using a singleresistor connected

Thermal Resistance Junction-ambient 80 120

between Pin 2 and thesense resistor. To have a better precision another resistor between Pin
2 and a reference voltage (Pin 11) must be added.

C/W

°

L4981B

peak current limiting. A precise current limitation is obtained using two external
resistor only. These resistorsmust 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 rectifiedmains voltagegenerates,

via a multiplier,the current reference for the currentamplifier.

5 CA-OUT Current amplifieroutput. An external RC network determinatesthe loop gain.
6 LFF Load feedforward; this voltage input pin allowsto 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 voltagereference (pin = 11).

7 VRMS Input for proportional RMS line voltage. theVRMS input compesates theline voltage changes.

Connecting a low pass filter between therectified line andthe pin 7, a DC voltage proportional
to the inputline RMS voltage is obtained. The best control isreached using input voltage
between 1.5V and 5.5V. Ifthisfunction is not used connectthis 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. inputis

9I

SENSE

an high impedence input like I
Current amplifierinverting input. Care must be takento avoid this pin goes down -0.5V.

. The MULT-OUT pin must be taken not below -0.5V.

SENSE

10 S-GND Signal ground.
11 V

REF

Output reference voltage (typ = 5.1V).Voltage refence at ± 2% of accuracy externally available,
it’s internallycurrent limitedand candeliver an output current up to 10mA.

12 SS 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 outputvoltage.

15 P-UVLO Programmable under voltage lock out threshold input. A voltage divider between supply

voltage and GND can be connected in orderto program the turn on threshold.

16 SYNC

(L4981A)

This synchronization input/output pin is CMOS logic compatible. Operating as SYNC in, a
rectangular wave must be applied at this pin. Opearting as SYNC out,a rectangular clock
pulse train is available to synchronize otherdevices.

FREQ-MOD

(L4981B)

17 R
18 C
19 V

OSC
OSC

CC

Frequency modulation current input. An external resistor must be connected between pin 16
and the rectified line voltage in order to modulate the oscillatorfrequency. Connecting pin 16 to
ground a fixed frequencyimposed by R

An external resistor connected to ground fixes the constant charging current of C

OSC

and C

is obtained.

OSC

OSC

.
An external capacitor connected to GND fixes the switching frequency.
Supply input voltage.

20 GDRV Output gate driver. Bipolar and DMOS transistors totem pole output stage candeliver peak

current in excess1A useful to drive MOSFET or IGBT power stages.

3/17

L4981A - L4981B

ELECTRICALCHARACTERISTICS

R

=24KΩ,CSS=1µF, V

V

OSC
FEED

= GND, V

IPK

= 1V,V

CA-OUT

= 1V, TJ=25°C

OVP

(Unlessotherwise specified V

= 3.5V, V

ISENSE

= 0V, V

LFF=VREF,IAC

= 18V, C

CC

= 1nF,

OSC

= 100µA, V

RMS

= 1V,

Symbol Prameter Test Condition Min. Typ. Max. Unit

ERROR AMPLIFIER SECTION

V

IO

I

IB

Input Offset Voltage –25°C<TJ<85°C ±8mV
Input Bias Current V

= 0V -500 -50 500 nA

FEED

Open Loop Gain 70 100 dB

V

13H

V

13L

-I

13

I

13

Output High voltage V

Output Low Voltage V

Output Source Current V
Output Sink Current V

FEED

I

VA-OUT

FEED

I

VA-OUT

FEED
FEED

= 4.7V

= -0.5mA

= 5.5V

= 0.5mA
= 4.7V; V
= 5.5V; V

5.5 6.5 7.5 V

0.4 1 V

= 3.5V 2 10 mA

VA-OUT

= 3.5V 4 20 mA

VA-OUT

REFERENCE SECTION

V

ref

∆V

ref

∆V

ref

I

ref sc

Reference OutputVoltage –25°C<TJ<85°C 4.97 5.1 5.23 V

=25°CI

T

j

Load Regulation 1mA ≤ I

–25°C<T

Line Regulation 12V ≤ VCC≤ 19V

–25°C<T

Short Circuit Current V

=0V 203050mA

ref

= 0 5.01 5.1 5.19 V

ref

ref

J

≤ 10mA

<85°C

315mV

310mV

<85°C

J

OSCILLATOR SECTION

f

V

I
I

V

osc

svp
18C
18D

18

Initial Accuracy Tj=25°C 85 100 115 KHz
Frequency Stability 12V ≤ V

–25°C<T

CC

J

≤ 19V

<85°C

80 100 120 KHz

Ramp Valley to Peak 4.7 5 5.3 V
Charge Current V
Discharge Current V

= 3.5V 0.45 0.55 0.65 mA

COSC

= 3.5V 11.5 mA

COSC

Ramp Valley Voltage 0.9 1.15 1.4 V

SYNC SECTION (Only for L4981A)

t

W

I

16

-I

16

V

16L

V

16H

t

d

FREQUENCY MODULATION FUNCTION

f

18max

f

18min

Output Pulse Width 50%Amplitude 0.3 0.8 µs
Sink Current with Low Output

Voltage
Source Current with High Output

Voltage

V
V

V
V

SYNC
COSC

SYNC
COSC

= 0.4V

=0V

= 4.5V

= 6.7V

0.4 0.8 mA

16 mA

Low Input Voltage 0.9 V
High Input Voltage 3.5 V
Pulse for Synchronization 800 ns

(Only for
Maximum Oscillation Frequency V
Minimum Oscillator Frequency I

L4981B

FREQ-MOD

FREQ-MOD

V

VRMS

I

FREQ-MOD

V

VRMS

)

= 0V (Pin 16) I

= 360µA (Pin16)

= 4V (Pin 7)

= 180µA (Pin16)

= 2V (Pin 7)

= 0 85 100 115 KHz

freq

74 KHz

76 KHz

SOFT START SECTION

Soft Start SourceCurrent VSS= 3V 60 100 140 µA
Output Saturation Voltage V3= 6V, ISS= 2mA 0.1 0.25 V

V

I

SS

12sat

4/17

L4981A - L4981B

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

SUPPLY VOLTAGE

V

CC

Operating Supply Voltage 19.5 V

OVER VOLTAGE PROTECTION COMPARATOR

Rising Threshold Voltage V

-20mV

ref

5.1 V
+20mV

ref

Hysteresis 180 250 320 mV
Input Bias Current 0.05 1
Propagation delay tooutput V

OVP=Vthr

+100mV 1 2

V

V

3Hys

I
t

thr

3
d

OVER CURRENT PROTECTIONCOMPARATOR

V

th

t

d

I

ipk

I

L

Threshold Voltage ±30 mV
Propagation delay toOutput V
Current Source Generator V
Leakage Current V

OCP=Vthr
IPK
IPK

-0.2V 0.4 0.9 µs
= -0.1V
= -0.1V

only for L4981A
only for L4981B

65 85 105 µA

5 µA

CURRENT AMPLIFIER SECTION

V

offset

I

9bias

Input Offset Voltage V
Input Bias Current V

MULT OUT=VSENSE
SENSE

Open Loop Gain 1.1V≤V

SVR Supply Voltage Rejection 12V ≤ V

V

MULT OUT

V

5H

V

5L

-I

5

I

5

Output High Voltage V

Output Low Voltage V

Output Source Current V
Output Sink Current 2 10 mA

MULT OUT

I

CA OUT

MULT OUT

I

CA OUT

MULT OUT

V

IAC

= 0V, V

= 0V -500 50 500 nA

CA OUT

CC

= 3.5V V
= 200mV

= -0.5mA, V

= -200mV

= 0.5mA, V

= 200mV,

= 3.5V ±2mV

6V 70 100 dB

≤

≤ 19V

SENSE

= 3.5V

68 90 dB

6.2 V

=0V

IAC

=0V

IAC

210 mA

= 3.5V

CA-OUT

0.9 V

OUTPUT SECTION

V

V

V

20L

20H

t

r

t

f

GDRV

Output Voltage Low I
Output Voltage High I

Output Voltage Rise Time C
Output Voltage Fall Time C
Voltage Clamp I

= 250mA 0.5 0.8 V

SINK

= 250mA

SOURCE

V

= 15V

CC

= 1nF 50 150 ns

OUT

= 1nF 30 100 ns

OUT

= 0mA 13 16 19 V

SOURCE

11.5 12.5 V

TOTAL STANDBY CURRENT SECTION

I

19start

I

19on

Supply Current before start up VCC= 14V 0.3 0.5 mA
Supply Current after turn on V

IAC

=0V,V

COSC

=0,

812mA

Pin17= Open

I

19

V

CC

Operating Supply Current Pin20 = 1nF 12 16 mA
Zener Voltage (*) 20 25 30 V

UNDER VOLTAGE LOCKOUT SECTION

V

V

th OFF

thON

Turn on Threshold 14.5 15.5 16.5 V
Turn off Threshold 9 10 11 V
Programmable Turn-on Threshold Pin 15 to V

CC

= 220K

10.6 12 13.4 V

Pin15 to GND = 33K

LOAD FEED FORWARD

I

LFF

V

I

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

Bias Current V6= 1.6V 70 140

= 5.3V 200 300 µA

V

6

Input Voltage Range 1.6 5.3 V

V

A

µ

s

µ

A

µ

5/17

L4981A - L4981B

ELECTRICALCHARACTERISTICS

(continued)

Symbol Prameter Test Condition Min. Typ. Max. Unit

MULTIPLIER SECTION

Multipler Output Current V

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

C

OSC

V

VA-OUT

V

MULTOUT

I

AC

V

VA-OUT

V

MULTOUT

I

AC

=0,V

=50µA, COSC =0V

= 4V, V

=0,V

= 200µA, C

= 2V, V

=0,V

= 100µA, C

= 2V, V

=0,V

= 100µA, COSC =0V

= 4V, V

=0,V

= 100µA, C

= 4V, V

=0,V

= 0V, IAC= 200µA

= 4V, V

=0,V

= 200µA, COSC =0V

= 2V, V

=0,V

=0,C

OSC

= 4V, V

VA-OUT

RMS
LFF

RMS
LFF

OSC

RMS
LFF

OSC

RMS
LFF

RMS
LFF

OSC

RMS
LFF

RMS
LFF

RMS
LFF

=0V

= 2V,

= 5.1V

= 2V,

= 5.1V

=0V

= 2V,

= 5.1V

=0V

= 4V,

= 5.1V

= 4V,

= 5.1V

=0V

= 2V,

= 2.5V

=4V

= 5.1V

= 4V,

= 5.1V

20 35 52

100 135 170 µA

10 20 30 µA

2 5.5 11

10 22 34 µA

20 37 54 µA

20 39 54

-2 0 2 µA

K Multiplier Gain 0.37

A

µ

A

µ

A

µ

I

MULT−OUT

= K ⋅ I

if VLFF =VREF; I
where: K1 = 1V

Figure 1:

MULTI-OUTvs. I

V

LFFD

(

V

AC

MULT−OUT

= 5.1V)

VA−OUT

= I

−

1.28

(V

(V

−OUT

VA

AC

(V

AC(VRMS

) ⋅ (

VRMS

− 1.28)

VRMS

= 1.7V;

0.8⋅V

2

)

2

)

LFF

⋅ K1

−

)

1.28

Figure2: MULTI-OUTvs. I

V

LFFD

= 5.1V)

AC(VRMS

= 2.2V;

6/17