LM5041BMTC NSC [National Semiconductor], LM5041BMTC Datasheet

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LM5041BMTC

Manufacturer Part Number
LM5041BMTC
Description
Cascaded PWM Controller
Manufacturer
NSC [National Semiconductor]
Datasheet

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© 2009 National Semiconductor Corporation
Cascaded PWM Controller
General Description
The LM5041B PWM controller contains all of the features
necessary to implement either current-fed or voltage-fed
push-pull or bridge power converters. These “Cascaded”
topologies are well suited for multiple output and higher power
applications. The LM5041B includes these four control out-
puts: the buck stage controls (HD and LD) and the push-pull
control outputs (PUSH and PULL). Push-pull outputs are driv-
en at 50% nominal duty cycle at one half of the switching
frequency of the buck stage and can be configured for either
a guaranteed overlap time (for current-fed applications) or a
guaranteed non-overlap time (for voltage-fed applications).
Push-pull stage MOSFETs can be driven directly from the in-
ternal gate drivers while the buck stage requires an external
driver such as the LM5102. The LM5041B includes a high-
voltage start-up regulator that operates over a wide input
range of 15V to 100V. The PWM controller is designed for
high-speed capability including an oscillator frequency range
up to 1 MHz and total propagation delays of less than 100 ns.
Additional features include line Under-Voltage Lock-Out
(UVLO), Soft-Start, an error amplifier, precision voltage ref-
erence, and thermal shutdown.
The differences between LM5041, LM5041A and LM5041B
are as follows: In the LM5041A and the LM5041B version, the
hiccup mode over-current protection is not employed and the
VCC bias regulator is not disabled by a low state at the SS
pin. In the LM5041B version, both the high and low side buck
stage gate drivers are forced to a low state when the controller
is disabled. In the LM5041 and the LM5041B version, the
buck stage controller is disabled by either a low state at the
UVLO pin or a low state at the SS pin. Also in the LM5041B
version, the REF pin 5V regulator is not disabled by a UVLO
pin low state.
Typical Application Circuit
Simplified Cascaded Push-Pull Power Converter
300864
LM5041B
Features
Applications
Packages
Internal Start-up Bias Regulator
Programmable Line Under-Voltage Lockout (UVLO) with
Adjustable Hysteresis
Current Mode Control
Internal Error Amplifier with Reference
Cycle-by-cycle Over-Current Protection
Leading Edge Blanking
Programmable Push-Pull Overlap or Dead Time
Internal 1.5A Push-Pull Gate Drivers
Programmable Soft-Start
Programmable Oscillator with Sync Capability
Precision Reference
Thermal Shutdown
Telecommunication Power Converters
Industrial Power Converters
Multi-Output Power Converters
TSSOP-16
LLP-16 (5x5 mm) Thermally Enhanced
30086401
www.national.com
May 1, 2009

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LM5041BMTC Summary of contents

Page 1

Cascaded PWM Controller General Description The LM5041B PWM controller contains all of the features necessary to implement either current-fed or voltage-fed push-pull or bridge power converters. These “Cascaded” topologies are well suited for multiple output and higher power applications. The ...

Page 2

... Connection Diagram Ordering Information Order Number LM5041BMTC LM5041BMTCX LM5041BSD LM5041BSDX Pin Descriptions Pin Pin Pin # Name Description V 1 Source Input Voltage Feedback Signal Output of the Internal 3 COMP Error Amplifier Precision 5 volt 4 REF reference output Main Buck PWM 5 HD control output ...

Page 3

Pin Pin Pin # Name Description 12 CS Current sense input 13 SS Soft-Start control Push-Pull overlap and 14 TIME dead time control Oscillator timing SYNC resistor pin and sync Line Under-Voltage 16 UVLO Shutdown LLP DAP ...

Page 4

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications GND GND CC All Other Inputs to GND Junction Temperature Storage Temperature Range Electrical ...

Page 5

Symbol Parameter Oscillator Frequency1 Frequency2 Sync threshold PWM Comparator Delay to Output Max Duty Cycle Min Duty Cycle COMP to PWM Comparator Gain COMP Open Circuit Voltage COMP Short Circuit Current Slope Compensation Slope Comp Amplitude UVLO Shutdown Under-Voltage Shutdown ...

Page 6

Typical Performance Characteristics V and Pin Current vs Temp Overlap Time vs R www.national.com 30086408 30086415 SET 30086411 30086409 Frequency vs RT 30086410 Dead Time vs R ...

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Overlap Time vs Temp 30086413 Error Amplifier Gain Phase 30086416 Dead Time vs Temp 7 30086414 www.national.com ...

Page 8

Block Diagram www.national.com Simplified Block Diagram 8 30086403 ...

Page 9

Detailed Operating Description The LM5041B PWM controller contains all of the features necessary to implement either current-fed or voltage-fed push-pull or bridge power converters. These “Cascaded” topologies are well suited for multiple output and higher power applications. The LM5041B includes ...

Page 10

PWM Comparator The PWM comparator compares the slope compensated cur- rent ramp signal to the loop error voltage from the internal error amplifier (COMP pin). This comparator is optimized for speed in order to achieve minimum controllable duty cycles. The ...

Page 11

Slope Compensation The PWM comparator compares the current sense signal to the voltage at the COMP pin. The output stage of the internal error amplifier generally drives the COMP pin. At duty cycles greater than 50%, current mode control circuits ...

Page 12

Typical Application www.national.com FIGURE 1. Simplified Cascaded Half-Bridge 12 30086406 ...

Page 13

Application Circuit: Input 35V to 80V, Output 2.5V, 50A 13 www.national.com ...

Page 14

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted Molded TSSOP-16 NS Package Number MTC16 16-Lead LLP Surface Mount Package NS Package Number SDA16A 14 ...

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Notes 15 www.national.com ...

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For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock and Timing www.national.com/timing Data Converters www.national.com/adc Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www.national.com/ldo ...

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