LM2524D/LM3524D Regulating Pulse Width Modulator
May 2, 2008
LM2524D/LM3524D
Regulating Pulse Width Modulator
General Description
The LM3524D family is an improved version of the industry
standard LM3524. It has improved specifications and addi-
tional features yet is pin for pin compatible with existing 3524
families. New features reduce the need for additional external
circuitry often required in the original version.
The LM3524D has a ±1% precision 5V reference. The current
carrying capability of the output drive transistors has been
raised to 200 mA while reducing V
CEsat
and increasing V
CE
breakdown to 60V. The common mode voltage range of the
error-amp has been raised to 5.5V to eliminate the need for
a resistive divider from the 5V reference.
In the LM3524D the circuit bias line has been isolated from
the shut-down pin. This prevents the oscillator pulse ampli-
tude and frequency from being disturbed by shut-down. Also
at high frequencies (≃300 kHz) the max. duty cycle per output
has been improved to 44% compared to 35% max. duty cycle
in other 3524s.
In addition, the LM3524D can now be synchronized external-
ly, through pin 3. Also a latch has been added to insure one
pulse per period even in noisy environments. The LM3524D
includes double pulse suppression logic that insures when a
shut-down condition is removed the state of the T-flip-flop will
change only after the first clock pulse has arrived. This feature
prevents the same output from being pulsed twice in a row,
thus reducing the possibility of core saturation in push-pull
designs.
Features
■
■
■
■
■
■
■
■
■
Fully interchangeable with standard LM3524 family
±1% precision 5V reference with thermal shut-down
Output current to 200 mA DC
60V output capability
Wide common mode input range for error-amp
One pulse per period (noise suppression)
Improved max. duty cycle at high frequencies
Double pulse suppression
Synchronize through pin 3
Connection Diagram
865002
Top View
Order Number LM2524DN or LM3524DN
See NS Package Number N16E
Order Number LM3524DM
See NS Package Number M16A
© 2008 National Semiconductor Corporation
8650
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LM2524D/LM3524D
Absolute Maximum Ratings
(Note 5)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
Collector Supply Voltage
(LM2524D)
(LM3524D)
Output Current DC (each)
Oscillator Charging Current (Pin 7)
40V
55V
40V
200 mA
5 mA
Internal Power Dissipation
Operating Junction Temperature
Range (Note 2)
LM2524D
LM3524D
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering 4 sec.)
M, N Pkg.
1W
−40°C to +125°C
0°C to +125°C
150°
−65°C to +150°C
260°C
Electrical Characteristics
(Note 1)
LM2524D
Symbol
Parameter
Conditions
Typ
REFERENCE
SECTION
V
REF
V
RLine
V
RLoad
Output Voltage
Line Regulation
Load Regulation
Ripple Rejection
I
OS
Short Circuit
Current
N
O
Output Noise
Long Term
Stability
OSCILLATOR
SECTION
f
OSC
f
OSC
Max. Freq.
Initial
Accuracy
R
T
= 1k, C
T
= 0.001 μF
(Note 7)
R
T
= 5.6k, C
T
= 0.01 μF
(Note 7)
R
T
= 2.7k, C
T
= 0.01 μF
(Note 7)
Δf
OSC
Δf
OSC
Freq. Change
with V
IN
Freq. Change
with Temp.
V
OSC
t
PW
Output Amplitude
(Pin 3) (Note 8)
Output Pulse
Width (Pin 3)
Sawtooth Peak
Voltage
R
T
= 5.6k, C
T
= 0.01 μF
3.4
3.6
3.8
3.8
V
Max
R
T
= 5.6k, C
T
= 0.01 μF
0.5
1.5
0.5
1.5
μs
Max
T
A
= −55°C to +125°C
at 20 kHz R
T
= 5.6k,
C
T
= 0.01 μF
R
T
= 5.6k, C
T
= 0.01 μF
3
2.4
3
2.4
V
Min
5
5
%
V
IN
= 8 to 40V
38
42
0.5
1
0.5
20
22.5
34
38
46
1.0
kHz
Max
%
Max
17.5
20
22.5
30
kHz
Max
kHz
Min
17.5
kHz
Min
550
500
350
kHz
Min
10 Hz
≤
f
≤
10 kHz
T
A
= 125°C
V
IN
= 8V to 40V
I
L
= 0 mA to 20 mA
f = 120 Hz
V
REF
= 0
50
180
40
20
100
40
20
5
10
10
66
25
50
200
100
mA Max
μV
rms Max
mV/kHr
4.85
5.15
15
15
4.80
5.20
30
25
10
10
66
25
5
4.75
5.25
25
25
50
50
V
Min
V
Max
mV
Max
mV
Max
dB
mA Min
Tested
Limit
(Note 3)
Design
Limit
(Note 4)
Typ
LM3524D
Tested
Limit
(Note 3)
Design
Limit
(Note 4)
Units
3
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LM2524D/LM3524D
LM2524D
Symbol
Parameter
Conditions
Typ
Common Mode
Voltage Range
SHUT
DOWN
SECTION
V
SD
I
SD
High Input
Voltage
High Input
Current
OUTPUT
SECTION
(EACH
OUTPUT)
V
CES
I
CES
Collector Emitter
Voltage Breakdown
Collector Leakage
Current
V
CESAT
V
EO
t
R
Saturation
Voltage
Emitter Output
Voltage
Rise Time
V
IN
= 20V,
I
E
= −250 μA
R
C
= 2k
t
F
V
IN
T
I
IN
Fall Time
Input Voltage
Range
Thermal Shutdown (Note 2)
Temp.
Stand By Current
V
IN
= 40V (Note 6)
160
5
10
R
C
= 2k
After Turn-on
100
8
40
160
5
100
200
200
V
CE
= 60V
V
CE
= 55V
V
CE
= 40V
I
E
= 20 mA
I
E
= 200 mA
I
E
= 50 mA
0.2
1.5
18
0.5
2.2
17
0.1
50
0.1
0.2
1.5
18
I
C
≤
100 μA
55
V
(Pin 2)
− V
(Pin 1)
≥
150 mV
I
(pin 10)
1
1
0.5
1.5
1
1
V
5
− V
4
= 300 mV
−0.7
1
Tested
Limit
(Note 3)
Design
Limit
(Note 4)
Typ
−0.7
1
LM3524D
Tested
Limit
(Note 3)
Design
Limit
(Note 4)
Units
V
Min
V
Max
0.5
1.5
V
Min
V
Max
mA
40
V
Min
μA
Max
50
0.7
2.5
17
V
Min
V
Max
ns
ns
8
40
V
Min
V
Max
°C
10
mA
SUPPLY
CHARACTERISTICS
SECTION
Note 1:
Unless otherwise stated, these specifications apply for T
A
= T
J
= 25°C. Boldface numbers apply over the rated temperature range: LM2524D is −40° to
85°C and LM3524D is 0°C to 70°C. V
IN
= 20V and f
OSC
= 20 kHz.
Note 2:
For operation at elevated temperatures, devices in the N package must be derated based on a thermal resistance of 86°C/W, junction to ambient. Devices
in the M package must be derated at 125°C/W, junction to ambient.
Note 3:
Tested limits are guaranteed and 100% tested in production.
Note 4:
Design limits are guaranteed (but not 100% production tested) over the indicated temperature and supply voltage range. These limits are not used to
calculate outgoing quality level.
Note 5:
Absolute maximum ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 6:
Pins 1, 4, 7, 8, 11, and 14 are grounded; Pin 2 = 2V. All other inputs and outputs open.
Note 7:
The value of a C
t
capacitor can vary with frequency. Careful selection of this capacitor must be made for high frequency operation. Polystyrene was used
in this test. NPO ceramic or polypropylene can also be used.
Note 8:
OSC amplitude is measured open circuit. Available current is limited to 1 mA so care must be exercised to limit capacitive loading of fast pulses.
5
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