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LM3524DM Datasheet

Download or read online National Semiconductor LM3524DM IC, REGULATING PWM, 16-SOIC pdf datasheet.
Also see for LM3524DM: Datasheet #2 (19 pages)

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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
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
Connection Diagram
© 2008 National Semiconductor Corporation
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
and increasing V
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
Top View
Order Number LM2524DN or LM3524DN
See NS Package Number N16E
Order Number LM3524DM
See NS Package Number M16A
May 2, 2008
Specifications of National Semiconductor LM3524DM
No. Of Outputs:
No. Of Pins:
Operating Temperature Range:
0°C To +125°C
Output Current:
Output Voltage:
Power Dissipation Pd:
Primary Input Voltage:
Termination Type:

Summary of Contents

Page 1

... One pulse per period (noise suppression) Improved max. duty cycle at high frequencies Double pulse suppression Synchronize through pin 3 865002 Top View Order Number LM2524DN or LM3524DN See NS Package Number N16E Order Number LM3524DM See NS Package Number M16A 8650 May 2, 2008 ...

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Block Diagram 2 865001 ...

Page 3

... Absolute Maximum Ratings 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) Electrical Characteristics (Note 1) Symbol Parameter REFERENCE ...

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Symbol Parameter Sawtooth Valley R T Voltage ERROR-AMP SECTION V Input Offset Voltage I Input Bias Current I Input Offset Current I Compensation V COSI IN(I) Current (Sink) I Compensation ...

Page 5

Symbol Parameter Common Mode Voltage Range V − SHUT DOWN SECTION V High Input V SD (Pin 2) Voltage 150 mV I High Input I SD (pin 10) Current OUTPUT SECTION (EACH OUTPUT) ...

Page 6

Typical Performance Characteristics Switching Transistor Peak Output Current vs Temperature Maximum & Minimum Duty Cycle Threshold Voltage Output Transistor Emitter Voltage Maximum Average Power Dissipation (N, M Packages) 865028 Output Transistor Saturation Voltage 865030 Reference Transistor Peak Output Current ...

Page 7

Standby Current vs Voltage Current Limit Sense Voltage Test Circuit 865034 865036 7 Standby Current vs Temperature 865035 865004 ...

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Functional Description INTERNAL VOLTAGE REGULATOR The LM3524D has an on-chip 5V, 50 mA, short circuit pro- tected voltage regulator. This voltage regulator provides a supply for all internal circuitry of the device and can be used as an external reference. ...

Page 9

The output of the amplifier, or input to the pulse width modu- lator, can be overridden easily as its output impedance is very high (Z 5 MΩ). For this reason a DC voltage can be applied O to pin 9 ...

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Typical Applications FIGURE 7. Positive Regulator, Step-Up Basic Configuration (I FIGURE 8. Positive Regulator, Step-Up Boosted Current Configuration 865011 80 mA) IN(MAX) 10 865012 ...

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FIGURE 9. Positive Regulator, Step-Down Basic Configuration (I 865013 80 mA) IN(MAX) 11 ...

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FIGURE 10. Positive Regulator, Step-Down Boosted Current Configuration FIGURE 11. Boosted Current Polarity Inverter 12 865014 865015 ...

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BASIC SWITCHING REGULATOR THEORY AND APPLICATIONS The basic circuit of a step-down switching regulator circuit is shown in Figure 12, along with a practical circuit design using the LM3524D in Figure 15. FIGURE 12. Basic Step-Down Switching Regulator FIGURE 13. ...

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Also, see LM1578 data sheet for graphical methods of induc- tor selection. CALCULATING OUTPUT FILTER CAPACITOR C Figure 13 shows L1's current with respect to Q1 times ( the collector of Q1). This curent must flow ...

Page 15

Staver Heatsink No. V5- BD344 Q2 2N5023 L1 >40 turns No. 22 wire on Ferroxcube No. K300502 Torroid core. FIGURE 15. 5V, 1 Amp Step-Down Switching Regulator 15 865020 ...

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Parameter Output Voltage Switching Frequency Short Circuit Current Limit Load Regulation Line Regulation Efficiency Output Ripple FIGURE 16. 5V, 1 Amp Switching Regulator, Foil Side TABLE 1. Conditions V 10V 10V, ...

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THE STEP-UP SWITCHING REGULATOR Figure 18 shows the basic circuit for a step-up switching reg- ulator. In this circuit Q1 is used as a switch to alternately apply V across inductor L1. During the time energy is drawn ...

Page 18

In calculating the output capacitor C supplies I during t . The voltage change time will be some ΔV ΔV or the output ripple of the regu lator. Calculation of C is: o ...

Page 19

L1 > 25 turns No. 24 wire on Ferroxcube No. K300502 Toroid core. FIGURE 20. 15V, 0.5A Step-Up Switching Regulator FIGURE 21. Replacing R3/R4 Divider in Figure 20 with Reference Circuit Improves Line Regulation FIGURE 22. Polarity Inverter Provides ...

Page 20

... Physical Dimensions inches (millimeters) unless otherwise noted Molded Surface-Mount Package (M) Order Number LM3524DM NS Package Number M16A 20 ...

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Molded Dual-In-Line Package (N) Order Number LM2524DN or LM3524DN NS Package Number N16E 21 ...

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... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers Audio Clock Conditioners Data Converters Displays Ethernet Interface LVDS Power Management Switching Regulators LDOs www ...

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