L4978 STMicroelectronics, L4978 Datasheet

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... THERMAL SHUTDOWN ■ SOFT START FUNCTION ■ 2 DESCRIPTION The L4978 is a step down monolithic power switching regulator delivering voltage be- tween 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 R of 0.25Ω ...

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... L4978 Table 2. Block Diagram THERMAL SHUTDOWN 2 SS_INH INHIBIT SOFTSTART 7 COMP 8 E/A FB 3.3V OSCILLATOR 3 OSC Figure 3. Pins Connection (Top view) GND 1 SS_INH 2 OSC 3 OUT 4 D97IN595 DIP-8 Table 3. Pin Description N° Pin Name 1 2 GND 2 3 SS_INH 3 4 OSC 2/13 VOLTAGES MONITOR INTERNAL REFERENCE 3 ...

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... 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. Parameter Parameter = 24V 24V) CC Function Minidip SO16 Max. 90 (*) 110 (*) Value int. limit -0.3 DIP-8 1 SO16 0.8 -40 to 150 L4978 Unit °C/W Unit °C 3/13 ...

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... L4978 Table 6. Electrical Characteristcs (T = 25° 2.7nF osc osc to T from 0 to 125°C j Symbol Parameter DYNAMIC CHARACTERISTIC V Operating input voltage range I V Output voltage o V Dropout voltage d I Maximum limiting current l Efficiency f Switching frequency s SVRR Supply voltage ripple rejection Switching Frequency Stability vs ...

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... C 4 22nF " Specification Referred ● Min. Typ. 0.78 0.85 2 2. =3.3V/ 126µH R (77120 STPS3L60U 330µ D98IN834B L4978 V (V) R3(KΩ) R4(KΩ) O 3.3 0 5.1 2 4.7 L4978 Max. Unit 0.92 V 2 300 kHz 5/13 ...

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... L4978 Figure 6. Quiescent drain current vs. input voltage. Iq (mA) 200KHz R =22K 1 C =1.2nF Tamb=25˚ Figure 7. Quiescent current vs. junction temperature Iq (mA 100KHz =35V -50 -30 - 110 Tj(˚C) Figure 8. Stand by drain current vs. input voltage. Ibias (µA) Vss=GND 150 Tj=25˚C 140 130 120 110 ...

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... Vo [V] [%] 95 Vcc=8V Vcc=8V Vcc=12V Vcc=12V 90 85 Vcc=24V 80 75 Vcc=48V 70 fsw=100kHz 65 Vo=5. 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1 [A] [%] 95 Vcc= Vcc=12V 80 Vcc=24V 75 70 Vo=3.36V 65 fsw=100kHz Vcc=48V 60 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Io [A] L4978 30 2.2 7/13 ...

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... L4978 Figure 18. Efficiency vs. output current. . η (%) 90 V =12V CC V =24V =48V 0.2 0.4 0.6 0.8 1.0 1.2 1.4 I Figure 19. Efficiency vs. output current. . η (%) V = =12V =24V =48V 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 I Figure 20. Efficiency vs. Vcc [%] 90 Vo=5.1V fsw=100kHz 85 Vo=5.1V fsw=200kHz Vo=3 ...

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... Figure 28. Open loop frequency and phase of error amplifier . GAIN D97IN786 (dB -50 (mV 100 = 100KHz -100 0 -150 -100 -200 D97IN745 470nF 330nF 220nF 100nF (V) CCmax . ccmax L (µH) fsw=200KHz 300 200 100 GAIN 0 Phase L4978 D97IN746 56nF 47nF 33nF 22nF max(V) CC D97IN787 Phase 135 8 10 f(Hz) 9/13 ...

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... L4978 3 Package Informations Figure 29. DIP-8 Mechanical Data & Package Dimensions mm DIM. MIN. TYP. MAX. A 3.32 a1 0.51 B 1.15 1.65 b 0.356 0.55 b1 0.204 0.304 D 10.92 E 7.95 9.75 e 2.54 e3 7.62 e4 7.62 F 6.6 I 5.08 L 3.18 3.81 Z 1.52 10/13 inch MIN. TYP. MAX. 0.131 0.020 0.045 ...

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... Mold flash, protusions or gate burrs shall not exceed 0.15mm per side. inch MIN. TYP. MAX. 0.093 0.104 0.004 0.012 0.013 0.200 0.009 0.013 0.398 0.413 0.291 0.299 0.050 0.394 0.419 0.010 0.030 0.016 0.050 0.004 OUTLINE AND MECHANICAL DATA SO16 (Wide) 0016021 C L4978 11/13 ...

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... L4978 Table 7. Revision History Date Revision October 2001 May 2005 12/13 8 First Issue 9 Modified D1 on the Fig. 4. Description of Changes ...

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