2.5A POWER SWITCHING REGULATOR 2.5A OUTPUT CURRENT 5.1V OPUTPUT V

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2.5A POWER SWITCHING REGULATOR 2.5A OUTPUT CURRENT 5.1V OPUTPUT V

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L4960
2.5A POWER SWITCHING REGULATOR
2.5A OUTPUT CURRENT 5.1V OPUTPUT VOLTAGE RANGE PRECISE ON-CHIP REFERENCE HIGH SWITCHING FREQUENCY VERY HIGH EFFICIENCY 90%) VERY EXTERNAL COMPONENTS SOFT START INTERNAL LIMITING CURRENT THERMAL SHUTDOWN
HEPTAWATT
ORDERING NUMBERS: L4960 (Vertical) L4960H (Horizontal)
DESCRIPTION L4960 monolithic power switching regulator delivering 2.5A voltage variable from step down configuration. Features device include current limiting, soft start, thermal protection 100% duty cycle continuous operation mode.
L4960is mounted Heptawatt plastic power package requires very external components. Efficient operation switching frequencies 150KHz allows reduction size cost external filter components.
BLOCK DIAGRAM
April 1995
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L4960
CONNECTION (Top view)
ABSOLUTE MAXIMUM RATINGS
Symbol Ptot Tstg Parameter Input voltage Input output voltage difference Negative output voltage Negative output peak voltage 0.1µs; 100KHz Voltage Voltage sink current source current Power dissipation Tcase 90°C Junction storage temperature Value Unit
FUNCTIONS
NAME SUPPLY VOLTAGE FUNCTION Unregulated voltage input. internal regulator powers internal logic. feedback terminal regulation loop. output connected directly this terminal 5.1V operation; connected divider higher voltages. series network connected between this terminal ground determines regulation loop gain characteristics. Common ground terminal. parallel network connected this terminal determines switching frequency. Soft start time constant. capacitor connected between this terminal ground define soft start time constant. This capacitor also determines average short circuit output current. Regulator output.
FEEDBACK INPUT
FREQUENCY COMPENSATION GROUND OSCILLATOR
SOFT START
OUTPUT
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THERMAL DATA
Symbol j-case j-amb Thermal resistance junction-case Thermal resistance junction-ambient Parameter Value Unit °C/W °C/W
ELECTRICAL CHARACTERISTICS (Refer test circuit, 35V, unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
DYNAMIC CHARACTERISTICS
Vref Vref Output voltage range Input voltage range Line regulation Load regulation Internal reference voltage (pin Average temperature coefficient refer voltage Dropout voltage Maximum operating load current Current limiting threshold (pin Input average current Efficiency Vref Vref 2.5A Vref Vref
0.5A
125°C Vref Vref 46V; 100KHz output short-circuit Vref
mV/°C
Supply voltage ripple rejection
2Vrms fripple 100Hz Vref
fmax
Switching frequency Voltage stability switching frequency Temperature stability switching frequency Maximum operating switching frequency Thermal shutdown junction temperature
125°C
Vref
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ELECTRICAL CHARACTERISTICS (continued)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
CHARACTERISTICS
Quiescent drain current 100% duty cycle pins open duty cycle -I7L Output leakage current duty cycle
SOFT START
I6SO I6SI Source current Sink current
ERROR AMPLIFIER
I3SI -I3SO High level output voltage level output voltage Sink output current Source output current Input bias current open loop gain 4.7V 5.3V 5.3V 4.7V 5.2V 100µA 100µA
OSCILLATOR
Oscillator source current
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L4960
CIRCUIT OPERATION (refer block diagram) L4960 monolithic stepdown switching regulator providing output voltages from 5.1V delivering 2.5A. regulation loop consists sawtooth oscillator, error amplifier, comparator output stage. error signal produced comparing output voltage with precise 5.1V on-chip reference (zener trimmed 2%). This error signal isthen compared with sawtooth signal generate fixed frequency pulse width modulated pulses which drive output stage. gain frequency stability loop adjusted external network connected Closing loop directly gives output voltage 5.1V. Higher voltages obtained inserting voltage divider. Output overcurrents switch prevented soft start function. error amplifier output initially clamped external capacitor allowed rise, linearly, this capacitor charged constant current source. Output overload protection provided form current limiter. load current sensed internal metal resistor connected comparator. When load current exceeds preset threshold this comparator sets flip flop which disables output stage discharges soft start capacitor. second comparator resets flip flop when voltage across soft start capacitor fallen 0.4V. output stage thus re-enabled output voltage rises under control soft start network. overload condition still present limiter will trigger again when threshold current reached. average short circuit current limited safe value dead time introduced soft start network. thermal overload circuit disables circuit operation when junction temperature reaches about 150°C hysteresis prevent unstable conditions.
Figure Soft start waveforms
Figure Current limiter waveforms
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L4960
Figure Test application circuit
(ROE) 150µH (COGEMA 946042) CORE TYPE: MAGNETICS 58206-A2 TURNS WIRE GAUGE: 0.8mm AWG)
Figure Quiescent drain current supply voltage duty cycle)
Figure Quiescent drain current supply voltage (100% duty cycle)
Figure Quiescent drain current unction temperature duty cycle)
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L4960
Figure Quiescent drain current junction temperature (100% duty cycle) Figure Reference voltage (pin Figure Reference voltage versus junction temperature (pin
Figure Open loop frequency phase responde error amplifier
Switc hing frequency input voltage
Figur itching frequency tion mperature
Switching frequency (see test circuit)
Line transie response
Load transient response
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L4960
Figure Supply voltage ripple rejection frequency Figure Dropout voltage between current Figure Dropout voltage junction temperature
Figure Power dissipation derating curve
output current
ffic output current
Effi output current
Effi ency output voltage
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L4960
APPLICATION INFORMATION
Figure Typical application circuit
(ROE) BYW80 SCHOTTKY DIODE SUGGESTED INDUCTOR: 150µH CORE TYPE: MAGNETICS 58206 TURNS: WIRE GAUGE: 0.8mm AWG), COGEMA 946042 U15/GUP15: TURNS: WIRE GAUGE: 0.8mm AWG), GAP: 1mm, COGEMA 969051.
Figure P.C. board component layout Fig. scale)
Resistor values standard output voltages 4.7K 4.7K 4.7K 4.7K 6.2K 9.1K
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L4960
APPLICATION INFORMATION Figure minimal 5.1V fixed regulator; Very component required
COGEMA 946042 969051 (ROE)
(TOROID CORE) (U15 CORE)
Figure Programmable power supply
5.1V 2.5A Load regulation 10mV 5.1V)
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L4960
APPLICATION INFORMATION (continued) Figure Microcomputer supply with 5.1V, -5V, +12V -12V outputs
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L4960
APPLICATION INFORMATION (continued) Figure DC-DC converter 5.1V/4A, 12V/2.5A; suggestion synchronize negative output
COGEMA 946042 (969051) COGEMA 946044 (946045) BYW80
Figure multiple supplies several L4960s synchronized shown
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L4960
APPLICATION INFORMATION (continued) Figure Regulator distributed supplies
MOUNTING INSTRUCTION power dissipatedin circuit must removed adding external heatsink. Thanks Heptawatt package attaching hetsink very simple, screw compression spring (clip) being sufficient. Between heatsink package better insert layer silicon grease, optimize thermal contact, electrical isolation needed between surfaces.
Figure Mounting example
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L4960
HEPTAWATT PACKAGE MECHANICAL DATA
DIM. MIN. 3.65 15.1 5.08 3.85 0.144 10.05 16.97 14.92 21.54 22.62 15.8 0.102 0.594 0.236 0.110 0.200 0.152 2.41 4.91 7.49 2.54 5.08 7.62 0.35 TYP. MAX. 1.37 1.35 0.55 2.67 5.21 10.4 10.4 0.396 0.668 0.587 0.848 0.891 0.118 0.622 0.260 0.095 0.193 0.295 0.100 0.200 0.300 0.094 0.047 0.014 0.024 MIN. inch TYP. MAX. 0.189 0.054 0.110 0.053 0.022 0.031 0.035 0.105 0.205 0.307 0.409 0.409
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L4960
Information furnished believed accurate reliable. However, SGS-THOMSON Microelectronics assumes responsibility consequences such information infringement patents other rights third parties which result from use. license granted implication otherwise under patent patent rights SGS-THOMSON Microelectronics. Specifications mentioned this publication subject change without notice. This publication supersedes replaces information previously supplied. SGS-THOMSON Microelectronics products authorized critical components life support devices systems without express written approval SGS-THOMSON Microelectronics. 1995 SGS-THOMSON Microelectronics Rights Reserved SGS-THOMSON Microelectronics GROUP COMPANIES Australia Brazil France Germany Hong Kong Italy Japan Korea Malaysia Malta Morocco Netherlands Singapore Spain Sweden Switzerland Taiwan Thaliand United Kingdom U.S.A.
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2.5A POWER SWITCHING REGULATOR 2.5A OUTPUT CURRENT 5.1V OPUTPUT V

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