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L4976 Dataheets PDF



Part Number L4976
Manufacturers STMicroelectronics
Logo STMicroelectronics
Description 1A STEP DOWN SWITCHING REGULATOR
Datasheet L4976 DatasheetL4976 Datasheet (PDF)

® L4976 1A STEP DOWN SWITCHING REGULATOR UP TO 1A STEP DOWN CONVERTER OPERATING INPUT VOLTAGE FROM 8V TO 55V PRECISE 5.1V REFERENCE VOLTAGE OUTPUT VOLTAGE ADJUSTABLE FROM 3.3V TO 50V SWITCHING FREQUENCY ADJUSTABLE UP TO 500KHz VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING (PULSE-BYPULSE AND HICCUP MODE) PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN DESCRIPTION The L4976 is a step down monolithic power switching regulator delivering 1A at a voltage betwe.

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® L4976 1A STEP DOWN SWITCHING REGULATOR UP TO 1A STEP DOWN CONVERTER OPERATING INPUT VOLTAGE FROM 8V TO 55V PRECISE 5.1V REFERENCE VOLTAGE OUTPUT VOLTAGE ADJUSTABLE FROM 3.3V TO 50V SWITCHING FREQUENCY ADJUSTABLE UP TO 500KHz VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING (PULSE-BYPULSE AND HICCUP MODE) PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN DESCRIPTION The L4976 is a step down monolithic power switching regulator delivering 1A at a voltage between 3.3V and 50V (selected by a simple external divider). Realized in BCD mixed technology, the device uses an internal power D-MOS transistor (with a typical Rdson of 0.25Ω) to obtain very high efficency and high switching speed. A switching frequency up to 250KHz is achievable (the maximum power dissipation of the packTYPICAL APPLICATION CIRCUIT Minidip SO16W ORDERING NUMBERS: L4976 (Minidip) L4976D (SO16) ages must be observed). A wide input voltage range between 8V to 55V and output voltages regulated from 3.3V to 40V cover the majority of today’s applications. Features of this new generations of DC-DC converter include pulse-by-pulse current limit, hiccup mode for short circuit protection, voltage feedforward regulation, protection against feedback loop disconnection and thermal shutdown. The device is available in plastic dual in line, MINIDIP 8 for standard assembly, and SO16W for SMD assembly. Vi=8V to 55V 5 R1 20K 3 C1 220µF 63V C7 220nF C2 2.7nF 2 7 8 L4976 4 1 6 L1 260µH (77120) D1 GI SB360 C8 330µF VO=3.3V/1A R2 9.1K C4 22nF C6 100nF May 2000 1/11 L4976 BLOCK DIAGRAM VCC 5 THERMAL SHUTDOWN VOLTAGES MONITOR CBOOT CHARGE VREF 2 VREF 5.1V COMP FB 7 8 E/A 3.3V PWM R S Q DRIVE OSCILLATOR CBOOT CHARGE AT LIGHT LOADS INTERNAL REFERENCE 6 BOOT 3.3V 3 OSC 1 GND 4 OUT PIN CONNECTIONS N.C. GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N.C. N.C. FB COMP BOOT VCC N.C. N.C. GND VREF OSC OUT 1 2 3 4 8 7 6 5 FB COMP BOOT VCC VREF OSC OUT OUT N.C. N.C. Minidip SO16W PIN FUNCTIONS DIP 1 2 3 SO (*) 2 3 4 Name GND VREF OSC Function Ground 5.1V Reference voltage with 20mA current capability. An external resistor connected between the unregulated input voltage and this pin and a capacitor connected from this pin to ground fix the switching frequency. (Line feed forward is automatically obtained) Stepdown regulator output Unregulated DC input voltage A capacitor connected between this pin and OUT allows to drive the internal VDMOS E/A output to be used for frequency compensation Stepdown feedback input. Connecting directly to this pin results in an output voltage of 3.3V. An external resistive divider is required for higher output voltages. 4 5 6 7 8 5, 6 11 12 13 14 OUT VCC BOOT COMP FB (*) Pins 1, 7, 8, 9, 10, 15 and 16 are not internally, electrically connected to the die. 2/11 L4976 THERMAL DATA Symbol R th(j-amb) Parameter Thermal Resistance Junction to ambient Max. Minidip 90 (*) SO16 110 (*) Unit °C/W (*) Package mounted on board. OPERATING TEMPERATURE RATING Symbol TJ Parameter Junction Temperature Range Value -40 to 150 Unit °C ABSOLUTE MAXIMUM RATINGS Symbol Minidip V5 V4 I4 V6-V5 V6 V7 V8 Ptot Tj,Tstg S016 V11 V5,V6 I5,I6 V12-V11 V12 V13 V14 Bootstrap voltage Analogs input voltage (VCC = 24V) (VCC = 20V) Power dissipation a Tamb ≤ 60°C Junction and storage temperature Minidip SO16 Input voltage Output DC voltage Output peak voltage at t = 0.1µs f=200KHz Maximum output current Parameter Value 58 -1 -5 int. limit. 14 70 12 6 -0.3 1 0.8 -40 to 150 V V V V V W W °C Unit V V V ELECTRICAL CHARACTERISTICS (Tj = 25°C, Cosc = 2.7nF, Rosc = 20kΩ, VCC = 24V, unless otherwise specified.) * Specification Refered to Tj from 0 to 125 °C Symbol VI Vo Parameter Operating input voltage range Output voltage Test Condition Vo = 3.3 to 50V; Io = 1A Io = 0.5A Io = 0.2 to 1A Vcc = 8 to 55V Vcc = 10V; Io = 1A Vcc = 8 to 55V Vo = 3.3V; Io = 1A Vi = Vcc+2VRMS; Vo = Vref; Io = 1.A; f ripple = 100Hz Vcc = 8 to 55V Tj = 0 to 125°C * Min. 8 3.33 3.292 3.22 Typ. Max. 55 3.39 3.427 3.5 0.55 0.88 2.5 110 Unit V V V V V V A % KHz dB % % DYNAMIC CHARACTERISTIC 3.36 3.36 3.36 0.44 2 85 100 * * * * Vd Il fs SVRR Dropout voltage Maximum limiting current Efficiency Switching frequency Supply voltage ripple rejection Voltage stability of switching frequency Temp. stability of switching frequency 1.5 90 60 3 4 6 3/11 L4976 ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Reference Section Reference Voltage Test Condition Min. 5.0 4.950 Typ. 5.1 5.1 5 2 6 65 Max. 5.2 5.250 10 10 25 100 Unit V V mV mV mV mA Line Regulation Load Regulation Short Circuit Current Iref = 0 to 10mA; VCC = 8 to 55V Iref = 0mA; VCC = 8 to 55V Vref = 0 to 5mA; VCC = 0 to 20mA * 30 DC Characteristics Iqop Iq VFB RL Total operating quiescent current Quiescent current Voltage Feedback Input Line regulation Ref. voltage stability vs temperature High level output voltage Low level output voltage Source output current Sink output current.


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