LM25037MT/NOPB National Semiconductor, LM25037MT/NOPB Datasheet

IC CTLR PWM C/V MODE 16-TSSOP

LM25037MT/NOPB

Manufacturer Part Number
LM25037MT/NOPB
Description
IC CTLR PWM C/V MODE 16-TSSOP
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheet

Specifications of LM25037MT/NOPB

Pwm Type
Voltage/Current Mode
Number Of Outputs
1
Frequency - Max
578kHz
Duty Cycle
88%
Voltage - Supply
5.5 V ~ 75 V
Buck
No
Boost
No
Flyback
No
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
No
Operating Temperature
-40°C ~ 125°C
Package / Case
16-TSSOP
Frequency-max
578kHz
For Use With
LM25037EVAL - BOARD EVAL FOR LM25037
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
LM25037MT
© 2010 National Semiconductor Corporation
Dual-Mode PWM Controller With Alternating Outputs
General Description
The LM25037 PWM controller contains all the features nec-
essary to implement balanced double-ended power converter
topologies, such as push-pull, half-bridge and full-bridge.
These double-ended topologies allow for higher efficiencies
and greater power densities compared to common single-
ended topologies such as the flyback and forward. The
LM25037 can be configured for either voltage mode or current
mode control with minimum external components. Two alter-
nating gate drive outputs are provided, each capable of 1.2A
peak output current. The LM25037 can be configured to op-
erate directly from the input voltage rail over an ultra-wide
range of 5.5V to 75V. Additional features include pro-
grammable maximum duty cycle limit, line under-voltage lock-
out, cycle-by-cycle current limit and a hiccup mode fault
protection with adjustable timeout delay, soft-start and a 2
MHz capable oscillator with synchronization capability, preci-
sion reference and thermal shutdown.
Simplified Push-Pull Power Converter
300651
LM25037/LM25037Q
Features
Package
LM25037Q is an Automotive Grade product that is AEC-
Q100 grade 1 qualified (-40°C to 125°C operating junction
temperature)
Ultra wide input operating range from 5.5V to 75V
Alternating outputs for double-ended topologies
Current-mode or feed-forward voltage-mode control
Programmable maximum duty cycle limit
2.0% feedback reference accuracy
High gain-bandwidth error amplifier
Programmable line under-voltage lockout (UVLO) with
adjustable hysteresis
Versatile dual mode over-current protection with hiccup
delay timer
Programmable soft-start
Precision 5V reference output
Current sense leading edge blanking
Resistor programmed 2 MHz capable oscillator
Oscillator synchronization capability with low frequency
lockout protection
TSSOP-16
January 8, 2010
www.national.com
30065101

Related parts for LM25037MT/NOPB

LM25037MT/NOPB Summary of contents

Page 1

... MHz capable oscillator with synchronization capability, preci- sion reference and thermal shutdown. Simplified Push-Pull Power Converter © 2010 National Semiconductor Corporation LM25037/LM25037Q Features ■ LM25037Q is an Automotive Grade product that is AEC- Q100 grade 1 qualified (-40° ...

Page 2

Connection Diagram Ordering Information Order Number Package Type NSC Package Drawing LM25037MT LM25037MTX TSSOP-16 LM25037QMT LM25037QMTX *Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant with the ...

Page 3

Pin Descriptions Pin Name Description 1 RAMP Pulse width modulator ramp 2 UVLO Line under-voltage lockout 3 COMP Input to the pulse width modulator 4 FB Feedback 5 RT2 Oscillator dead-time control 6 AGND Analog ground 7 RT1 Oscillator maximum ...

Page 4

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN to GND VCC, RAMP , OUTA, OUTB to GND CS to GND UVLO, FB, RT2, RT1, SS, REF to GND COMP, RES(Note 2) Electrical Characteristics apply over full operating junction temperature range of −40° 125°C. V kΩ ...

Page 5

Symbol Parameter Soft-Stop Current Sink Oscillator (RT1 and RT2 Pins) DT Dead-Time Dead-Time Frequency 1 (at OUTA, half SW1 oscillator frequency) F Frequency 2 (at OUTA, half SW2 oscillator frequency) DC level Input Sync ...

Page 6

Typical Performance Characteristics Typical Application Circuit Efficiency Start-Up Regulator Current (UVLO = REF REF www.national.com V VCC 30065150 30065104 Feedback Amplifier Gain/Phase 30065106 6 and REF VIN 30065103 VCC VCC ...

Page 7

Oscillator Frequency vs RT1 30065108 V vs Temperature FB 30065111 Dead-Time vs Temperature 30065113 Dead-Time vs RT2 Oscillator Frequency vs Temperature Soft-Start and Restart Current vs Temperature 7 30065110 30065112 30065114 www.national.com ...

Page 8

Block Diagram www.national.com FIGURE 1. Simplified Block Diagram 8 30065118 ...

Page 9

Functional Description The LM25037 PWM controller contains all the features nec- essary to implement double-ended power converter topolo- gies such as push-pull, half-bridge and full-bridge. The unique architecture allows the modulator to be configured for either voltage-mode or current-mode control. ...

Page 10

When designing with a current sense resistor, all the noise sensitive, low power ground con- nections should be connected together near the AGND pin, and a single connection should be made to the power ground ...

Page 11

SOFT-START The soft-start circuit allows the regulator to gradually reach a steady state operating point, thereby reducing start-up stress- es and current surges. When bias is supplied to the LM25037, the SS pin capacitor is discharged by an internal MOSFET. ...

Page 12

CURRENT MODE The LM25037 can be configured for current mode control by injecting a signal representative of primary current into the RAMP pin. One way to achieve this is shown in components R and C are used to filter leading ...

Page 13

FIGURE 5. Current Mode Configuration with Slope Compensation FIGURE 6. Timing Diagram for Current Mode Configuration 13 30065122 30065123 www.national.com ...

Page 14

OSCILLATOR The LM25037 oscillator frequency and the maximum duty cy- cle are set by two external resistors connected between the RT1 and RT2 pins to AGND. The minimum dead-time be- tween OUTA and OUTB pulses is proportional to the RT2 ...

Page 15

REF) disabled. This helps to prevent catastrophic failures from accidental device overheating. During thermal shutdown, the soft-start capacitor is fully discharged and the controller follows a normal start-up sequence after the junc- tion temperature falls to the operating ...

Page 16

CURRENT MODE CONTROL USING THE LM25037 The LM25037 can be configured in current mode control by applying the primary current signal into the RAMP pin. One way to achieve this is shown in Figure plified push-pull converter. The primary current ...

Page 17

OSC current sense resistor ( mΩ, slope compensation will suffice. The slope compensation "volts" that re- sults from the above expression ...

Page 18

FIGURE 12. Current Sense Using Transformer 18 30065136 ...

Page 19

FIGURE 13. Current Sense Using Current Sense Resistor (R1) UVLO DIVIDER SELECTION A dedicated comparator connected to the UVLO pin detects an input under-voltage condition. When the UVLO pin voltage is below 0.45V, the LM25037 controller low ...

Page 20

For example, if the LM25037 enabled when V reaches 33V, and disabled when V PWR should be 113 kΩ, and R2 should be 4.42 kΩ. The voltage at the UVLO pin should not exceed 7V at any ...

Page 21

HICCUP MODE CURRENT LIMIT RESTART (RES) The basic operation of the hiccup mode current limit is de- scribed in the functional description. The delay time to the In the case of continuous cycle-by-cycle current limit detec- tion at the CS ...

Page 22

www.national.com 22 ...

Page 23

Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead TSSOP Package NS Package Number MTC16 23 www.national.com ...

Page 24

... 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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