LINFINITY SG1525A, SG2525A, SG3525A Service Manual

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SG1525A/SG2525A/SG3525A
SG1527A/SG2527A/SG3527A

REGULATING PULSE WIDTH MODULATOR

DESCRIPTION

The SG1525A/1527A series of pulse width modulator integrated circuits are
designed to offer improved performance and lower external parts count when used
to implement all types of switching power supplies. The on-chip +5.1 volt reference
is trimmed to ±1% initial accuracy and the input common-mode range of the error
amplifier includes the reference voltage, eliminating external potentiometers and
divider resistors. A Sync input to the oscillator allows multiple units to be slaved
together, or a single unit to be synchronized to an external system clock. A single
resistor between the C
adjustment. These devices also feature built-in soft-start circuitry with only a timing
capacitor required externally. A Shutdown pin controls both the soft-start circuitry
and the output stages, providing instantaneous turn-off with soft-start recycle for
slow turn-on. These functions are also controlled by an undervoltage lockout which
keeps the outputs off and the soft-start capacitor discharged for input voltages less
than that required for normal operation. Another unique feature of these PWM
circuits is a latch following the comparator. Once a PWM pulse has been terminated
for any reason, the outputs will remain off for the duration of the period. The latch
is reset with each clock pulse. The output stages are totem-pole designs capable
of sourcing or sinking in excess of 200mA. The SG1525A output stage features
NOR logic, giving a LOW output for an OFF state. The SG1527A utilizes OR logic
which results in a HIGH output level when OFF.

pin and the Discharge pin provides a wide range of deadtime

T

BLOCK DIAGRAM

FEATURES

••

• 8V to 35V operation

••

••

• 5.1V reference trimmed to ±1%

••

••

• 100Hz to 500KHz oscillator range

••

••

• Separate oscillator sync terminal

••

••

• Adjustable deadtime control

••

••

• Internal soft-start

••

••

• Input undervoltage lockout

••

••

• Latching P.W.M. to prevent multiple

••

pulses

••

• Dual source/sink output drivers

••

HIGH RELIABILITY FEATURES

- SG1525A, SG1527A

♦♦

♦ Available to MIL-STD-883B

♦♦
♦♦

♦ MIL-M38510/12602BEA - JAN1525AJ

♦♦
♦♦

♦ MIL-M38510/12604BEA - JAN1527AJ

♦♦
♦♦

♦ Radiation data available

♦♦
♦♦

♦ LMI level "S" processing available

♦♦

11/91 Rev 1.3 10/96 LINFINITY Microelectronics Inc.

Copyright  1996 11861 Western Avenue

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∞ ∞

∞ Garden Grove, CA 92841

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ABSOLUTE MAXIMUM RATINGS (Note 1)

Supply Voltage (+VIN) .......................................................

Collector Supply Voltage (V

Logic Inputs .......................................................

Analog Inputs .......................................................

) ...........................................

C

-0.3V to 5.5V

-0.3V to V

Output Current, Source or Sink ...................................

Reference Load Current ...............................................

Note 1. Values beyond which damage may occur.

THERMAL DATA

J Package:

Thermal Resistance­Thermal Resistance-

DW Package:

Thermal Resistance­Thermal Resistance-

L Package:

Thermal Resistance­Thermal Resistance-

N Package:

Thermal Resistance­Thermal Resistance-

Junction to Case, θ
Junction to Ambient, θ

Junction to Case, θ
Junction to Ambient, θ

Junction to Case, θ
Junction to Ambient, θ

Junction to Case, θ
Junction to Ambient, θ

JC

JC

JC

JC

.................. 30°C/W

.............. 80°C/W

JA

.................. 40°C/W

............. 95°C/W

JA

.................. 35°C/W

........... 120°C/W

JA

................... 40°C/W

............. 65°C/W

JA

40V
40V

500mA

50mA

SG1525A/SG1527A SERIES

Oscillator Charging Current ............................................

Operating Junction Temperature Range

Hermetic (J, L Packages) .....................................

IN

Plastic (N, DW Packages ) .......................................

Storage Temperature Range ..........................

Lead Temperature (Soldering, 10 seconds) .................

Note A. Junction Temperature Calculation: TJ = TA + (PD x θJA).
Note B. The above numbers for

θJC are maximums for the limiting

thermal resistance of the package in a standard mount­ing configuration. The θ
guidelines for the thermal performance of the device/pc-

numbers are meant to be

JA

board system. All of the above assume no ambient
airflow.

5mA

150°C
150°C

-65°C to 150°C
300°C

RECOMMENDED OPERATING CONDITIONS (Note 2)

Input Voltage (+VIN) ................................................

Collector Voltage (V

Sink/Source Load Current (steady state) .............

) ..........................................

C

Sink/Source Load Current (peak) .........................

Reference Load Current ........................................

Oscillator Frequency Range .......................

100Hz to 350KHz

Oscillator Timing Resistor (RT) ........................

Note 2: Range over which the device is functional.

8V to 35V

4.5V to 35V
0 to 100mA
0 to 400mA

0 to 20mA

2KΩ to 150KΩ

Deadtime Resistor Range (R

Maximum Shutdown Source Impedance .........................

Oscillator Timing Capacitor (C
Operating Ambient Temperature Range

) .............................

D

) ...................

T

SG1525A/SG1527A ....................................

SG2525A/SG2527A ......................................

SG3525A/SG3527A .........................................

0Ω to 500Ω

5KΩ

0.001µF to 0.1µF

-55°C to 125°C

-25°C to 85°C
0°C to 70°C

ELECTRICAL CHARACTERISTICS

(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1525A/SG1527A with -55° C ≤ TA ≤ 125°C,
SG2525A/SG2527A with -25°C ≤ TA ≤ 85°C, SG3525A/SG3527A with 0°C ≤ TA ≤ 70°C, and +VIN = 20V. Low duty cycle pulse testing techniques are
used which maintains junction and case temperatures equal to the ambient temperature.)

SG1525A/2525A
SG1527A/2527A

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

Reference Section

5.15

5.10

Output Voltage
Line Regulation
Load Regulation
Temperature Stability

(Note 3)

Total Output Voltage Range (Note 3)
Short Circuit Current
Output Noise Voltage

(Note 3)

Long Term Stability (Note 3)

Note 3. These parameters, although guaranteed over the recommended operating conditions, are not 100% tested in production.
Note 4. F
Note 5. Applies to SG1525A/2525A/3525A only, due to polarity of output pulses.

= 40KHz (RT = 3.6KΩ, CT = 0.01µF, RD = 0Ω)

OSC

TJ = 25°C
V

= 8V to 35V

IN

= 0 to 20mA

I

L

Over Operating Temperature Range
Over Line, Load and Temperature
V

= 0V, TJ = 25°C

REF

10Hz ≤ f ≤ 10KHz, T

= 125°C

T

J

= 25°C

J

5.05

5.00

10
20
20

80
40
20

30
50
50

5.20
100
200

50

SG3525A
SG3527A

5.00

4.95

5.10
10
20
20

80
40
20

5.20
30
50
50

5.25

100
200

50

UnitsTest ConditionsParameter

V
mV
mV
mV

V
mA

µVrms

mV/khr

11/91 Rev 1.3 10/96 LINFINITY Microelectronics Inc.

Copyright  1996 11861 Western Avenue

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∞ Garden Grove, CA 92841

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ELECTRICAL CHARACTERISTICS (continued)

SG1525A/SG1527A SERIES

SG1525A/2525A
SG1527A/2527A UnitsTest ConditionsParameter

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

Oscillator Section

Initial Accuracy
Voltage Stability
Temperature Stability
Minimum Frequency (Note 3)
Maximum Frequency (Note 3)
Current Mirror
Clock Amplitude
Clock Width
Sync Threshold
Sync Input Current

Error Amplifier Section (V

Input Offset Voltage

(Note 4)

(Note 3)

= 5.1V)

CM

TJ = 25°C
V

= 8V to 35V

IN

MIN ≤ T
R
R
I

RT

T

≤ MAX

J

= 150KΩ, CT = 0.1µF

T

= 2KΩ, CT = 1nF

T

= 2mA

= 25°C

J

Sync Voltage = 3.5V

37.6

350

1.7

3.0

0.3

1.2

40

±0.3

±3

2.0

3.5

0.5

2.0

1.0

0.5
Input Bias Current
Input Offset Current
DC Open Loop Gain
Gain-Bandwidth Product
Output Low Level
Output High Level
Common Mode Rejection
Supply Voltage Rejection

(Note 3)

R

≥10MΩ, TJ = 25°C

L

= 0dB, TJ = 25°C

A

V

V

= 1.5V to 5.2V

CM

V

= 8V to 35V

IN

60

1

3.8
60
50

75

0.2

5.6
75
60

P.W.M. Comparator Section

V

Minimum Duty Cycle
Maximum Duty Cycle
Input Threshold

(Note 4)

Input Bias Current

= 0.6V

COMP

V

= 3.6V

COMP

Zero Duty Cycle
Maximum Duty Cycle

45

0.6

49

0.9

3.3

.05

Soft-Start Section

50

Soft Start Current
Soft Start Voltage
Shutdown Input Current

Output Drivers Section

Output High Level
Output Low Level
Undervoltage Lockout

Collector Leakage

(Note 5)

Rise Time
Fall Time
Shutdown Delay

(Note 3)

V

SHUTDOWN

V

SHUTDOWN

V

(each transistor, VC = 20V)

SHUTDOWN

I

SOURCE

I

SOURCE

I

SINK

I

SINK

V

COMP

V

C

C
C
V

SD

= 0V
= 2V
= 2.5V

= 20mA

= 100mA
= 20mA
= 100mA

and VSS = High
= 35V
= 1nF, TJ = 25°C

L

= 1nF, TJ = 25°C

L

= 3V, CS = 0, TJ = 25°C

25

18
17

0.4

0.4

19
18

0.2

1.0

6

100

50

0.2

Total Standby Current

Standby Current VIN = 35V mA20142014

SG3525A
SG3527A

KHz

42.4

40

37.6

42.4
%

±2

350

1.7

3.0

0.3

1.2

60

1

3.8
60
50

45

0.6

25 50

18
17

6

±1
±3

2.0

3.5

0.5

2.0

1.0

2
1

75

2

0.2

5.6
75
60

49

0.9

3.3

.05

0.4

0.4

19
18

0.2

1.0

7

100

50

0.2

±6

150

2.2

1.0

2.8

2.5

10
10

1

0.5

0

3.6

2.0

80

0.6

1.0

0.4

2.2
8

200
600
300

0.5

%

Hz

KHz

mA

V

µs

V

mA

mV

µA
µA

dB

MHz

V

V
dB
dB

%
%

V

V

µA

µA

V

mA

V

V

V

V

V
µA

ns
ns
µs

±1
±6

150

2.2

1.0

2.8

2.5

5

1

10

1

2

0.5

0

3.6

2.0

80

0.6

1.0

0.4

2.2

7

8
200
600
300

0.5

11/91 Rev 1.3 10/96 LINFINITY Microelectronics Inc.

Copyright  1996 11861 Western Avenue

3 [phone]

∞ ∞

∞ Garden Grove, CA 92841

∞ ∞

∞∞

∞ FAX: [phone]

∞∞