LM5026MT/NOPB National Semiconductor, LM5026MT/NOPB Datasheet

CURRENT MODE-ACTIVE RESET

LM5026MT/NOPB

Manufacturer Part Number
LM5026MT/NOPB
Description
CURRENT MODE-ACTIVE RESET
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheet

Specifications of LM5026MT/NOPB

Pwm Type
Current Mode
Number Of Outputs
2
Frequency - Max
1MHz
Duty Cycle
92.5%
Voltage - Supply
13 V ~ 100 V
Buck
Yes
Boost
Yes
Flyback
Yes
Inverting
Yes
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
-40°C ~ 125°C
Package / Case
16-TSSOP
Frequency-max
1MHz
For Use With
LM5026EVAL - BOARD EVALUATION LM5026
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
*LM5026MT
*LM5026MT/NOPB
LM5026MT

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM5026MT/NOPB
Manufacturer:
TI
Quantity:
3 000
Part Number:
LM5026MT/NOPB
0
© 2010 National Semiconductor Corporation
Active Clamp Current Mode PWM Controller
General Description
The LM5026 PWM controller contains all of the features nec-
essary to implement power converters utilizing the active
clamp / reset technique with current mode control. With the
active clamp technique, higher efficiencies and greater power
densities can be realized compared to conventional catch
winding or RDC clamp / reset techniques. Two control outputs
are provided, the main power switch control (OUT_A) and the
active clamp switch control (OUT_B). The device can be con-
figured to control either a P-Channel or N-Channel clamp
switch. The main gate driver features a compound configu-
ration, consisting of both MOS and Bipolar devices, providing
superior gate drive characteristics. The LM5026 can be con-
figured to operate with bias voltages over a wide input range
of 8V to 100V. Additional features include programmable
maximum duty cycle, line under-voltage lockout, cycle-by-cy-
cle current limit, hiccup mode fault operation with adjustable
timeout delay, PWM slope compensation, soft-start, 1MHz
capable oscillator with synchronization input / output capabil-
ity, precision reference and thermal shutdown.
Typical Application Circuit
Simplified Forward Power Converter with Active Clamp Reset
201479
LM5026
Features
Packages
Current Mode Control
Internal 100V Start-up Bias Regulator
3A Compound Main Gate Driver
High Bandwidth Opto-coupler Interface
Programmable Line Under-Voltage Lockout (UVLO) with
Adjustable Hysteresis
Versatile Dual Mode Over-Current Protection with hiccup
delay timer
Programmable Overlap or Deadtime between the Main
and Active Clamp Outputs
Programmable Maximum Duty Cycle Clamp
Programmable Soft-start
Leading Edge Blanking
Resistor Programmed 1MHz Capable Oscillator
Oscillator Sync I/O Capability
Precision 5V Reference
TSSOP-16
LLP-16 (5x5 mm) Thermally Enhanced
March 9, 2010
www.national.com
20147901

Related parts for LM5026MT/NOPB

LM5026MT/NOPB Summary of contents

Page 1

... PWM slope compensation, soft-start, 1MHz capable oscillator with synchronization input / output capabil- ity, precision reference and thermal shutdown. Typical Application Circuit Simplified Forward Power Converter with Active Clamp Reset © 2010 National Semiconductor Corporation LM5026 Features ■ Current Mode Control ■ ...

Page 2

Connection Diagrams 16-Lead TSSOP Ordering Information Order Number Package Type LM5026MT TSSOP-16 LM5026MTX TSSOP-16 LM5026SD LLP-16 LM5026SDX LLP-16 Pin Descriptions Pin Name Description 1 VIN Input Voltage Source 2 UVLO Line Under-Voltage Lockout An external voltage divider from the power ...

Page 3

Pin Name Description 9 OUT_B Active Clamp Output Driver 10 PGND Power Ground 11 AGND Analog Return 12 SS Soft-start 13 COMP Input to the Pulse Width Modulator 14 RT Oscillator Frequency Control Normally biased at 2V. The total external ...

Page 4

Block Diagram www.national.com FIGURE 1. Simplified Block Diagram 4 20147912 ...

Page 5

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications GND GND GND COMP Input Current All other inputs to GND Electrical Characteristics Specifications with standard typeface are for T perature range 48V 10V 30.0kΩ ...

Page 6

Symbol Parameter Over Current Restart Restart Threshold Fault Charging Current Discharging Current Soft-Start Soft-start Current Source Soft-stop Current Sink Soft-start Current Source following a restart event Oscillator Frequency1 Frequency2 SYNC Source Current SYNC Sink Impedance Can sync ...

Page 7

Symbol Parameter Thermal Shutdown T Thermal Shutdown SD Temp. Thermal Shutdown Hysteresis Thermal Resistance θ Junction to Ambient MTC Package JA SDA Package Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings ...

Page 8

Oscillator Frequency vs RT Overlap Time vs R Deadtime vs R www.national.com Oscillator Frequency vs Temperature 20147906 SET 20147908 SET 20147910 8 20147907 Overlap Time vs Temperature 20147909 Deadtime vs Temperature 20147911 ...

Page 9

Max Duty Cycle vs UVLO COMP Current vs INV PWM Comparator Voltage Max Duty Cycle vs DCL 20147935 20147937 9 20147936 www.national.com ...

Page 10

Detailed Operating Description The LM5026 PWM controller contains all of the features nec- essary to implement power converters utilizing the active clamp reset technique with current mode control. With the active clamp reset, higher efficiencies and greater power den- sities ...

Page 11

The rising edge overlap or deadtime and the falling edge overlap or deadtime are identical and are independent of op- erating frequency or duty cycle. The magnitude of the overlap/ deadtime can be calculated as follows: Overlap Time = 2.8 ...

Page 12

For duty cycles greater than 50 percent, current mode control circuits are subject to sub-harmonic oscillation. By adding an additional fixed slope voltage ramp signal (slope compensa- tion) to the current sense signal, this oscillation can be avoid- ed. The ...

Page 13

FIGURE 6. Maximum Duty Cycle vs UVLO Voltage Soft-Start/Soft-Stop The soft-start circuit allows the regulator to gradually reach a steady state operating point, thereby reducing start-up stress- es and current surges. Upon turn-on, the SS pin capacitor is discharged by ...

Page 14

For example, the Oscillator and Sync Capability The LM5026 oscillator frequency is set by the external resis- tance connected between the RT ...

Page 15

FIGURE 10. Oscillator Sync I/O Block Diagram Thermal Protection Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event the maximum junction temper- ature is exceeded. When activated, typically at 165°C, the controller is forced into ...

Page 16

OSCILLATOR (RT, SYNC) Oscillator (RT, SYNC) The oscillator frequency is generally selected in conjunction with the design of the system mag- netic components along with the volume and efficiency goals for a given power converter design. The total RT resistance ...

Page 17

FIGURE 15. Current Sense Using a Current Sense Transformer FIGURE 16. Current Sense Using a Source Sense Resistor (R1) HICCUP MODE CURRENT LIMIT RESTART (RES) The basic operation of the hiccup mode current limit restart is described in the functional ...

Page 18

If the application requires no delay from the first detection of a current limit condition to the onset of the hiccup mode (t1 = 0), the RES pin can be left open (no external capacitor). ...

Page 19

Layout considerations are critical for the current sense filter current sense transformer is used, both leads of the trans- former secondary should be routed to the sense filter com- ponents and to the IC pins. The ground side ...

Page 20

www.national.com 20 ...

Page 21

Physical Dimensions inches (millimeters) unless otherwise noted Note recommended that the exposed pad be connected to Pin 11 (AGND). Molded TSSOP-16 NS Package Number MTC16 16-Lead LLP Surface Mount Package NS Package Number SDA16A 21 www.national.com ...

Page 22

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com 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 LED Lighting www ...

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