SGS Thomson Microelectronics L5991D, L5991AD, L5991A, L5991 Datasheet

L5991



PRIMARY CONTROLLER WITH STANDBY

CURRENT-MODE CONTROLPWM
SWITCHINGFREQUENCYUPTO1MHz
LOW START-UP CURRENT (< 120µA)
HIGH-CURRENT OUTPUT DRIVE SUITABLE

FOR POWERMOSFET(1A)
FULLY LATCHED PWM LOGIC WITH DOU-

BLE PULSE SUPPRESSION
PROGRAMMABLEDUTYCYCLE
100%AND50%MAXIMUMDUTY CYCLELIMIT
STANDBYFUNCTION
PROGRAMMABLESOFT START
PRIMARY OVERCURRENT FAULT DETEC-

TION WITH RE-STARTDELAY
PWMUVLO WITH HYSTERESIS
IN/OUTSYNCHRONIZATION
LATCHEDDISABLE
INTERNAL 100ns LEADING EDGE BLANK-

ING OF CURRENT SENSE
PACKAGE:DIP16 ANDSO16

DESCRIPTION

This primary controllerI.C., developed in BCD60II
technology, has been designed to implement off

L5991A

MULTIPOWER BCD TECHNOLOGY

DIP16 SO16

ORDERING NUMBERS:

line or DC-DC power supply applications using a
fixedfrequencycurrentmode control.
Based on a standard current mode PWM control­ler this device includes some features such as
programmablesoft start, IN/OUT synchronization,
disable (to be usedfor overvoltageprotection and
for power management), precise maximum Duty
Cycle Control, 100ns leading edge blanking on
current sense, pulse by pulse current limit, over­current protection with soft start intervention, and
Standbyfunction for oscillatorfrequencyreduction
when the converteris lightlyloaded.

L5991/L5991A (DIP16)

L5991D/L5991AD (SO16)

BLOCK DIAGRAM

RCT

3

DC

14

DIS

2.5V

13

ISEN

1.2V

SS

August 1999

+

-

-

+

OVER CURRENT

+

-

DIS

BLANKING

1V R

SYNC DC-LIM

TIMING2

T

PWM

FAULT

SOFT-START

2R

12

SGND COMP

25V

15V/10V

VREF OK

CLK

DIS

V

CC

Vref

+

PWM UVLO

-

SQ
R

STAND-BY ST-BY

2.5V7

+

E/A

-

6

13V

VREF

VREF
48151

D97IN725A

9

V

C

10

OUT

11

PGND

16

5

VFB

1/23

L5991 - L5991A

ABSOLUTEMAXIMUMRATINGS

Symbol Parameter Value Unit

V

CC Supply Voltage (I

I

OUT

Output Peak Pulse Current 1.5 A
Analog Inputs & Outputs (6,7) -0.3 to 8 V
Analog Inputs & Outputs (1,2,3,4,5,15,14,13, 16) -0.3 to 6 V

P

tot

T

j

T

stg

(*) maximum package power dissipation limits must be observed

Power Dissipation @ T

Junction Temperature, Operating Range -40 to 150 °C
Storage Temperature, Operating Range -55 to 150 °C

PIN CONNECTION

< 50mA) (*) selflimit V

CC

@T

=70°C (DIP16)

amb

=50°C (SO16)

amb

1

0.83

W
W

SYNC

RCT

DC

VREF

VFB

COMP

SS

V

CC

1
2
3
4
5
6
7 OUT
8V

15
14
13
12
11
10

ST-BY16
DC-LIM
DIS
ISEN
SGND
PGND

9

C

THERMAL DATA

Symbol Parameter Value Unit

R

th j-amb

Thermal Resistance Junction -Ambient (DIP16) 80
Thermal Resistance Junction -Ambient (SO16) 120

PIN FUNCTIONS

N. Name Function

1 SYNC Synchronization. A synchronization pulse terminates the PWM cycle and discharges Ct
2 RCT Oscillator pin for external C

T,RA,RB

3 DC Duty Cycle control
4 VREF 5.0V +/-1.5% reference voltage @ 25°C
5 VFB Error Amplifier Inverting input
6 COMP Error Amplifier Output
7 SS Soft start pin for external capacitor Css
8V
9V

CC Supply for internal ”Signal” circuitry

C

Supply for Power section
10 OUT High current totem pole output
11 PGND Power ground
12 SGND Signal ground
13 ISEN Current sense
14 DIS Disable. It must never be left floating. TIE to SGND if not used.
15 DC-LIM Connecting this pin to Vref, DC is limited to 50%. If it is left floating or grounded no limitation is

imposed
16 ST-BY Standby. Connect a resistor to RCT. Connect to VREF or floating if not used.

components

C/W

°

C/W

°

2/23

L5991 - L5991A

ELECTRICALCHARACTERISTICS

CC

=15V; Tj= 0 to 105°C; RT=13.3kΩ(*)CT= 1nF;

(V

unless otherwisespecified.)

Symbol Parameter Test Condition Min. Typ. Max. Unit

REFERENCE SECTION

V

REF

T

S

I

OS

OSCILLATOR SECTION

ERROR AMPLIFIER SECTION

V

I

G

OPL

SVR Supply Voltage Rejection V

V

OL

V

OH

O Output Source Current VCOMP > 4V, V

I

S

R

PWM CURRENT SENSE SECTION

I

b

I

S

V

t

SOFT START SECTION

I

SSC

I

SSD

V

SSSAT

V

SSCLAMP

LEADING EDGE BLANKING

OUTPUT SECTION

V

OL

V

OH

V

OUT CLAMP

(*) RT=RA//RB,RA=RB= 27kΩ, see Fig. 22.

Output Voltage Tj=25°C; IO= 1mA 4.925 5.0 5.075 V
Line Regulation V
Load Regulation I

= 12 to 20V; Tj=25°C 2.0 10 mV

CC

= 1 to 10mA; Tj=25°C 2.0 10 mV

O

Temperature Stability 0.4 mV/°C
Total Variation Line, Load, Temperature 4.80 5.0 5.130 V
Short Circuit Current Vref = 0V 30 150 mA
Power Down/UVLO V

CC

= 6V; I

Initial Accuracy pin 15 = Vref; T

pin 15 = Vref; V
pin 15 = Vref; V

Duty Cycle pin 3 = 0,7V, pin 15 = V

pin 3 = 0.7V, pin 15 = OPEN
pin 3 = 3.2V, pin 15 = V

pin 3 = 3.2V, pin 15 = OPEN

= 0.5mA 0.2 0.5 V

sink

j

V

comp

= 12 to 20V

CC

V

comp

= 12 to 20V

CC

V

comp

=25°C

= 4.5V
= 4.5V
=2V

REF

95 100 105 kHz
93 100 107 kHz

46.5 50 53.5 kHz
0

0

REF

47

93
Duty Cycle Accuracy pin 3 = 2.79V, pin 15 = OPEN 75 80 85 %
Oscillator Ramp Peak 2.8 3.0 3.2 V
Oscillator Ramp Valley 0.75 0.9 1.05 V

Input Bias Current V

to GND 0.2 3.0 µA

FB

Input Voltage VCOMP =VFB 2.42 2.5 2.58 V
Open Loop Gain V

Output Low Voltage I
Output High Voltage I

Output Sink Current V

= 2to 4V 60 90 dB

COMP

= 12 to 20V 85 dB

CC

= 2mA 1.1 V

sink

= 0.5mA, VFB= 2.3V 5 6 V

source

= 2.3V 0.5 1.3 2.5 mA

FB

COMP = 1.1V,V

= 2.7V 2 6 mA

FB

Unit Gain Bandwidth 1.7 4 MHz
Slew Rate 8 V/µs

Input Bias Current I
Maximum Input Signal V

=0 3 15

sen

= 5V 0.92 1.0 1.08 V

COMP

Delay to Output 70 100 ns
Gain 2.85 3 3.15 V/V
Fault Threshold Voltage 1.1 1.2 1.3 V

SS Charge Current Tj=25°C 142026µA
SS Discharge Current VSS = 0.6V Tj=25°C 5 10 15
SS Saturation Voltage DC = 0% 0.6 V
SS Clamp Voltage 7 V

Internal Masking Time 100 ns

Output Low Voltage IO= 250mA 1.0 V
Output High Voltage IO= 20mA; VCC= 12V 10 10.5 V

= 200mA; VCC = 12V 9 10 V

I

O

Output Clamp Voltage IO= 5mA; VCC = 20V 13 V
Collector Leakage V

CC = 20V VC = 24V 2 20 µA

%
%

%
%

A

µ

A

µ

3/23

L5991 - L5991A

ELECTRICALCHARACTERISTICS

(continued.)

Symbol Parameter Test Condition Min. Typ. Max. Unit

OUTPUT SECTION

Fall Time C
Rise Time C
UVLO Saturation V

O

C

O
O

C

O

CC =V

I

sink

= 1nF
= 2.5nF

= 1nF
= 2.5nF

C

= 10mA

= 0 to V

CCON

20
35

50
70

60 ns

100 ns

1.0 V

SUPPLY SECTION

V

CCON

V

CCOFF

V

Startup voltage L5991

L5991A147.8

Minimum Operating Voltage

L5991

L5991A

hys

UVLOHysteresis L5991

L5991A

I

S

I

op

I

q

V

Z

Start Up Current Before Turn-on at:

V

CC =V

C=VCCON

-0.5V
Operating Current CT=1nF, RT=13.3kΩ,CO=1nF 9 13 mA
Quiescent Current (After turn on), CT = 1nF,

R

= 13.3kΩ,CO=0nF

T

Zener Voltage I8= 20mA 21 25 30 V

9
7

4.5

0.5
40 75 120 µA

15

8.4
10

7.6

16

9

11

8.2

5

0.8

7.0 10 mA

STANDBY FUNCTION

I

V

REF-VST-BY

V

T1

Standby Threshold V

= 2mA 45 mV

ST-BY

Falling 2.5 V

comp

Rising 4.0 V

V

comp

SYNCHRONIZATION SECTION

Master Operation

V

1

I

1

Clock Amplitude I
Clock Source Current Vclock = 3.5V 3 7 mA

= 0.8mA 4 V

SOURCE

Slave Operation

V

1

Sync Pulse Low Level 1 V

High Level 3.5 V

I

1

Sync Pulse Current VSYNC = 3.5V 0.5 mA

OVER CURRENT PROTECTION

V

t

Fault Threshold Voltage 1.1 1.2 1.3 V

DISABLE SECTION

Shutdown threshold 2.4 2.5 2.6 V

I

SH

Shutdown Current VCC= 15V 330 µA

ns
ns

V
V

V
V

V
V

Figure 1. L5991 - Quiescentcurrent vs. input

voltage.
(X = 7.6V and Y= 8.4V for L5991A)

Iq [m A]

30
20

8
6

4

0.2

0.15

0.1

0.05
0

0 4 8 12162024

4/23

V 14 = 0, P in2 = ope n

Tj = 25°C

X

Y

Vcc [V]

28

Figure2. L5991 - Quiescentcurrent vs.input

voltage (after disable).
(X = 7.6V and Y= 8.4V for L5991A)

Iq [µ A]

350
300
250
200
150
100

50

0

0 4 8 12162024

X

Vcc [V]

V14 = Vref
Tj = 25 °C

Y

L5991 - L5991A

Figure 3. Quiescent currentvs. input voltage.

Iq [mA]

9.0

V14= 0, V5 = Vref

8.5

8.0

7.5

7.0
8 1012141618202224

Rt = 4.5K ohm ,Tj = 25° C

1Mhz

100Khz

Vcc [V]

500Khz

300Khz

Figure 5. Quiescent currentvs. input voltage

and switchingfrequency.

Iq[mA]
36

Co= 1nF,Tj = 25°C

30

24

DC= 100%

1MHz

Figure4. Quiescentcurrent vs. input voltage

and switchingfrequency.

Iq [m A]
36

30

24

18

12

6

0

Co = 1nF, Tj = 25°C

DC = 0 %

1M Hz

500KHz
300KHz

100KHz

8 10121416182022

Vcc [V]

Figure6. Reference voltage vs. load current.

Vref [V]

5.1

5.05

Vcc=15V
Tj= 25°C

18

12

6

0

8 10121416182022

Vcc[V]

500KHz

300KHz

100KHz

Figure 7. Vref vs. junctiontemperature.

Vref [V])

5.1

5.05

5

4.95

4.9

-50 -25 0 25 50 75 100 125 150

Vcc = 15V
Iref = 1mA

Tj (°C)

5

4.95

4.9
0 5 10 15 20 25

Iref [mA]

Figure8. Vref vs. junctiontemperature.

Vref [V]

5.1

Vcc = 15V

5.05

5

4.95

4.9

-50 -25 0 25 50 75 100 125 150

Iref= 20mA

Tj (°C)

5/23

L5991 - L5991A

Figure 9. Vref SVRR vs. switchingfrequency.

SVRR (dB)

120

80

40

0

1 10 100 1000 10000

fsw (Hz)

Vcc=15V
Vp-p=1V

Figure 11. Outputsaturation.

Vsat = V [V]

2.5

2

1.5

10

Vcc = Vc = 15V

Tj= 25°C

Figure10. Outputsaturation.

Vsat = V [V]

16

14

12

10

8

6

0 0.2 0.4 0.6 0.8 1 1.2

10

Vcc = Vc = 15V

Tj = 2 5 °C

Isource [A]

Figure12. UVLO Saturation

Ipin10 [mA]
50

40

30

Vcc < Vccon

beforeturn-o n

1

0.5

0

0 0.2 0.4 0.6 0. 8 1 1.2

Isink [A ]

Figure13.Timingresistorvs.switchi n gfrequency.

fsw (KHz)

5000

2000
1000

500

200
100

50

20
10

5.6nF

10 20 30 40

Vcc = 15V, V15 =0V
Tj = 25°C

2.2nF

Rt (kohm)

100pF

220pF

470pF

1nF

20

10

0

0 200 400 600 800 1,000 1,200 1,400

Vpin10 [mV]

Figure14. Switching frequency vs. tempera-

ture.

fsw (KHz)
320

Rt= 4.5Kohm, Ct = 1nF

310

300

290

280

-50 -25 0 25 50 75 100 125 150

Vcc = 15V,V15=Vref

Tj (°C)

6/23