March 2005
LM2524D/LM3524D
Regulating Pulse Width Modulator
one pulse per period even in noisy environments. The
LM3524D includes double pulse suppression logic that in-
sures 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.
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 exter-
nal circuitry often required in the original version.
The LM3524D has a 1% precision 5V reference. The cur-
rent carrying capability of the output drive transistors has
been raised to 200 mA while reducing VCEsat and increasing
VCE 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.
Features
n Fully interchangeable with standard LM3524 family
n
1% precision 5V reference with thermal shut-down
n Output current to 200 mA DC
n 60V output capability
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.
n Wide common mode input range for error-amp
n One pulse per period (noise suppression)
n Improved max. duty cycle at high frequencies
n Double pulse suppression
n Synchronize through pin 3
In addition, the LM3524D can now be synchronized exter-
nally, through pin 3. Also a latch has been added to insure
Connection Diagram
00865002
Top View
Order Number LM2524DN or LM3524DN
See NS Package Number N16E
Order Number LM3524DM
See NS Package Number M16A
© 2005 National Semiconductor Corporation
DS008650
www.national.com