Datasheet SG2524N, SG2524P, SG3524N, SG3524P Datasheet (SGS Thomson Microelectronics)

SG2524



REGULATING PULSE WIDTH MODULATORS

COMPLETE PWM POWER CONTROL CIR­CUITRY

UNCOMMITTED OUTPUTS FOR SINGLE­ENDED OR PUSH PULLAPPLICATIONS

LOW STANDBY CURRENT8mA TYPICAL
OPERATIONUP TO 300KHz
1% MAXIMUM TEMPERATURE VARIATION

OF REFERENCEVOLTAGE

DESCRIPTION

The SG2524, and SG3524 incorporate on a sin­gle monolithic chip all thefunction required for the
construction of regulating power suppies inverters
or switching regulators.They can also be usedas
the control element for high power-outputapplica­tions. The SG3524 family was designed for
switching regulators of either polarity, trans­former-coupled dc-to-dc converters, transformer­less voltage doublers and polarityconverter appli­cations employing fixed-frequency, pulse-width
modulation techniques. The dual alternating out­puts allows either single-ended or push-pull appli-

SG3524

DIP16 SO16

ORDERING NUMBERS: SG2524N (DIP16)

SG3524N (DIP16)
SG2524P (SO16)
SG3524P (SO16)

cations. Each device includes an on-ship refer­ence, error amplifier, programmable oscillator,
pulse-steering flip flop, two uncommitted output
transistors, a high-gain comparator, and current­limiting andshut-down circuitry.

BLOCK DIAGRAM

June 2000

This is advanced information on a new product now in development or undergoingevaluation. Details are subject to change without notice.

1/9

SG2524 - SG3524

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

IN

I

C

I

R

I

T

P

tot

T

stg

T

op

PIN CONNECTION(Top view)

Supply Voltage 40 V
Collector Output Current 100 mA
Reference Output Current 50 mA
Current Through CTTerminal – 5 mA
Total Power Dissipation at T

=70°C 1000 mW

amb

Storage Temperature Range – 65 to 150 °C
Operating Ambient Temperature Range:

SG2524
SG3524

–25to85

0to70

°C

C

°

THERMAL DATA

Symbol Parameter DIP16 SO16 Unit

R

th j-amb

R

th j-alumina

(*) Thermal resistance junction-alumina with the device soldered onthe middle of an alumina supporting substrate measuring 15 x 20mm;

0.65mm thickness with infiniteheatsink.

Thermal Resistance Junction-ambient Max.
Thermal Resistance Junction-alumina (*) Max.

2/9

80

–

50

–

°C/W

C/W

°

SG2524- SG3524

ELECTRICAL CHARACTERISTICS (unless otherwise stated, these specifications apply for Tj = -25 to

+85°C for the SG2524, and0 to70°C for the SG3524,V

= 20V, and f = 20KHz).

IN

Symbol Parameter Test Condition

SG2524 SG3524

Min. Typ. Max. Min. Typ. Max.

REFERENCE SECTION

V

∆V
∆V

Output Voltage 4.8 5 5.2 4.6 5 5.4 V

REF

Line Regulation VIN= 8 to 40V 10 20 10 30 mV

REF

Load Regulation IL= 0 to 20mA 20 50 20 50 mV

REF

Ripple Rejection f = 120Hz, T
Short Circuit Current

=0,Tj=25°C 100 100 mA

V

REF

=25°C66 66dB

j

Limit

∆V

/∆T Temperature Stability Over Operating

REF

0.3 1 0.3 1 %

Temperature range

V

∆

Long Term Stability Tj = 125°C, t = 1000Hrs 20 20 mV

REF

OSCILLATOR SECTION

f

MAX

f/∆T Temperature Stability Over Operating

∆

Maximum Frequency CT= 0.001µF, RT=2KΩ 300 300 KHz
Initial Accuracy R
Voltage Stability V

and CTConstant 5 5 %

T

= 8 to 40V, Tj=25°C1 1%

IN

22%

Temperature Range
Output Amplitude Pin 3, T
Output Pulse Width C

=25°C 3.5 3.5 V

j

= 0.01µF, Tj=25°C 0.5 0.5 µs

T

ERROR AMPLIFIER SECTION

V

G
CMV Common Mode Voltage T
CMR Common Mode Rejection T

V

Input Offset Voltage VCM= 2.5V 0.5 5 2 10 mV

OS

Input Bias Current 2 10 2 10 µA

I

b

Open Loop Voltage Gain 72 80 60 80 dB

V

=25°C 1.8 3.4 1.8 3.4 V

j

=25°C7070dB

j

B Small Signal Bandwidth A

Output Voltage Tj=25°C 0.5 3.8 0.5 3.8 V

O

= 0dB, Tj=25°C 3 3 MHz

V

COMPARATOR SECTION

Duty-cycle % Each Output On 0 45 0 45 %

V

Input Threshold Zero Duty-cycle 1 1 V

IT

Maximum Duty-cycle 3.5 3.5 V

Input Bias Current 1 1 µA

I

b

CURRENT LIMITING SECTION

Sense Voltage Pin 9 = 2V with Error

190 200 210 180 200 220 mV
Amp. Set for Max. Out.
T

=25°C

j

Sense Voltage T.C. 0.2 0.2 mV/°C

CMV Common Mode Voltage –1 1 –1 1

OUTPUT SECTION(each output)

Collector-emitter Voltage 40 40 V
Collector Leackage Curr. V
Saturation Voltage I
Emitter Output Voltage V
Rise Time RC=2KΩ,Tj=25°C 0.2 0.2

t

r

Fall Time RC=2KΩ,Tj=25°C 0.1 0.1 µs

t

f

(*) Total Standby Current VIN= 40V 8 10 8 10 mA

I

q

(*) Excluding oscillator charging current,error and current limit dividers, and with outputs open.

= 40V 0.1 50 0.1 50 µA

CE

= 50mA 1 2 1 2 V

C

= 20V 17 18 17 18 V

IN

Unit

µ

s

3/9

SG2524 - SG3524

Figure 1:

Figure 3:

Open-loopVoltage Amplificationof

ErrorAmplifier vs. Frequency

OutputDead Time vs. Timing

CapacitanceValue.

Figure2:

Figure4:

OscillatorFrequency vs. Timing

Components.

OutputSaturationVoltagevs. load

Current.

Figure 5:

4/9

OpenLoop Test Circuit.

SG2524- SG3524

PRINCIPLESOF OPERATION

The SG2524/3524 is a fixed frequency pulse­with-modulation voltage regulator control circuit.
The regulator operates at a frequency that is pro­grammed by one timing resistor (R
ing capacitor (C
charging current for C
voltage ramp at C

). RTestablished a constant

T

. This results in a linear

T

, which is fed to the compara-

T

) and one tim-

T

tor providing linear control of the output pulse
width by the error amplifier. the SG2524/3524
contains, an on-board5V regulatorthat serves as
a reference as well as powering the
SG2524/3524’s internal control circuitry and is
also useful in supplyingexternal support functions.
This reference voltage is lowered externally by a
resistor divider to provide a reference within the
common mode range the error amplifier or an ex­ternal reference may be used. The power supply
output is sensed by a second resistor divider net­work to generalea feedbacksignal to error ampli­fier. The amplifier output voltage is then com­pared to the linear voltage ramp at C

. The

T

resulting modulated pulse out of the high-gain
comparator is then steered to the appropriate out­put pass transistors (Q

or QB) by the pulse-

A

steering flip-flop, which is synchronously toggled
by the oscillator output. The oscillator output
pulse also serves as a blanking pulse to assure
both output are never on simultaneously during
the transition times. The width of the blanking
pulse is controlled by the value of C

. Theoutputs

T

may be applied in a push-pull configuration in
which their frequencyishalf that of the base oscil­lator, or paralleled for single-ended applicationsin
which the frequency is equal to that of the oscilla­tor. The output of the error amplifier shares a
common input to the comparator with the current
limiting at shutdown circuitry and can be overrid­den by signals from either of these inputs. This
common point is also available externally and
may be employed to control the gain of, or to
compensate, the error amplifier, or to provide ad­ditional controlto the regulator.

RECOMMENDED OPERATING CONDITIONS

Supply voltage V
Reference Output Current 0 to 20mA
Current trough C
Timing Resistor, R
Timing Capacitor, C

IN

Terminal - 0.03to -2mA

T

T

T

8 to 40V

1.8 to 100KΩ

0.001 to 0.1µF

TYPICALAPPLICATIONSDATA

OSCILLATOR
The oscillator controls the frequency of the

SG2524 and is programmed by R

and CTac-

T

cording to the approximateformula:

1.18

=

f

R

TCT

where:

Ω

is in K

R

T

C

is in µF

T

f is in KHz
Pratical values of C

0.1µF. Pratical values of R

fall between 0.001 and

T

fall between 1.8 and

T

100KΩ. This results in a frequency rangetypically
from 120Hzto to 500KHz.

BLANKING
The output pulse of oscillator is used as a blank-

ing pulse at the output. This pulse width is con­trolled by the value of C

.If small values of CTare

T

required for frequency control, the oscillator out­put pulse width may still be increased by applying
a shunt capacitance of up to 100pF from pin 3 to
ground. If still greater dead-time is required, it
should be accomplished by limiting the maximum
duty cycle by clamping the output of the error am­plifier. This can easily be done with the circuit be­low:

Figure6.

SYNCRONOUS OPERATION
When an external clock is desired, a clock pulse

of approximately 3V can be applied directlyto the
oscillator output terminal. The impedance to
ground at this point is approximately 2KΩ. In this
configuration R

must be selected for a clock

TCT

period slightlygreater than that the external clock.
If two more SG2524 regulatorsare to be operated

synchronously, all oscillator output terminals
should be tied together, all C

terminals con-

T

nected to a single timing capacitor, and timing re­sistor connected to a single R
other R
V

REF

tween the C

terminals can be left open or shorted to

T

. Minimum lead lengths should be used be-

terminals.

T

terminal. The

T

5/9

SG2524 - SG3524

Figure 7

: FlybackConverter Circuit.

Figure 8: PUSH-PULLTransformer-coupledcircuit.

6/9

SG2524- SG3524

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

a1 0.51 0.020

B 0.77 1.65 0.030 0.065

b 0.5 0.020

b1 0.25 0.010

D 20 0.787
E 8.5 0.335

e 2.54 0.100

e3 17.78 0.700

F 7.1 0.280

I 5.1 0.201
L 3.3 0.130

Z 1.27 0.050

mm inch

OUTLINE AND

MECHANICAL DATA

DIP16

7/9

SG2524 - SG3524

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 1.75 0.069
a1 0.1 0.25 0.004 0.009
a2 1.6 0.063

b 0.35 0.46 0.014 0.018

b1 0.19 0.25 0.007 0.010

C 0.5 0.020
c1 45°(typ.)

D (1) 9.8 10 0.386 0.394

E 5.8 6.2 0.228 0.244

e 1.27 0.050

e3 8.89 0.350

F (1) 3.8 4 0.150 0.157

G 4.6 5.3 0.181 0.209

L 0.4 1.27 0.016 0.050
M 0.62 0.024
S

mm inch

8°(max.)

OUTLINE AND

MECHANICAL DATA

SO16 Narrow

(1)D and F do not include mold flashor protrusions. Moldflashor potrusions shall not exceed0.15mm (.006inch).

8/9

SG2524- SG3524

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of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

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