Fujitsu MB3788 User Manual

DS04-27209-3EFUJITSU SEMICONDUCTORDATA SHEETASSPSWITCHING REGULATORCONTROLLERMB3788 DESCRIPTION The MB3788 is a dual-channel PWM-type switching reg

MB378810 STANDARD CHARACTERISTIC CURVES(Continued)2.52.01.51.00.50048121620PowercurrentlCC (mA)Supply voltage VCC (V)5432100 4 8 12 16 20Referencevol

MB378811(Continued)VCC = 6 VVFB = 1.6 VTA = +25°C1008060402000 5K 10K 50K 100K 500K 1M1.9V1.3VDutyDtr (%) Input oscillating frequency (Hz)40200-20-401

MB378812 HOW TO SET OUTPUT VOLTAGE+-VREFVOUTRNFR1R2RRVOUT = (R1 + R2)VREF2 × R2Note: Set the output voltage in the positive ra

MB378813 HOW TO SET OUTPUT CURRENTThe output circuit is configured in a push-pull type as shown in Figure 1. The ON current value of the outputcur

MB378814 HOW TO SET TIME CONSTANT FOR TIMER & LATCH-TYPE SHORT-CIRCUITPROTECTION CIRCUITIf the load conditions of the switching regulator are s

MB378815 PROCESSING WITHOUT USING SCP PINIf the timer and latch-type short-circuit protection circuit is not used, connect the SCP pin (pin 15) to

MB378816 EQUIVALENT SERIES RESISTANCE OF SMOOTHING CAPACITOR AND STABILITY OFDC/DC CONVERTERThe equivalent series resistance (ESR) of the smoothing

MB378817(Reference Data)The phase margin is halved by changing the smoothing capacitor from an aluminum electrolytic capacitor (Rc= 1.0 Ω) to a semico

MB378818 APPLICATION CIRCUIT+15 V+24 VDC motor 1DC motor 224150 Ω232021221000 pFChannel 1 (dB)<Logic power supply>(b)22 µH3 V10 µFCa2Cb2OUT2V

MB378819 NOTES ON USE• Take account of common impedance when designing the earth line on a printed wiring board.• Take measures against static elec

MB37882(Continued)• High-frequency operation: 100 kHz to 1 MHz• On-chip timer and latch-type short-circuit detection circuit• Wide error amplifier in

MB378820 PACKAGE DIMENSION24-pin plastic SSOP(FPT-24P-M03)Note 1) *1 : Resin protrusion. (Each side : +0.15 (.006) Max) .Note 2) *2 : These dimensi

MB3788FUJITSU LIMITEDAll Rights Reserved.The contents of this document are subject to change without notice. Customers are advised to consult with FUJ

MB37883 PIN DESCRIPTIONNote: The alphabetic characters in parenthesis above indicate the following input pins.(C): Comparator(E): Error amplifier

MB37884 BLOCK DIAGRAM24Channel 1-IN1 (E)FB1-IN1 (C)+IN1 (E)1254Ca1VCC(out)OUT1Cb11113143CTL2VCCCTL1VE110 12GND-IN(PWM)SCPVREF1.9 V1.3 V+-+-+-1.5 V0

MB37885 FUNCTIONAL DESCRIPTION1. Major Functions(1) Reference voltage power circuitThe reference voltage power supply produces a reference voltage

MB378863. Protection Functions(1) Timer and latch-type short-circuit protection circuitThe SCP comparator detects the output voltage levels of two com

MB37887 ABSOLUTE MAXIMUM RATINGS*: Value obtained when mounted on 4 cm × 4 cm double-sided epoxy substrateWARNING: Semiconductor devices can be perma

MB37888 ELECTICAL CHARACTERISTICS(Continued)(VCC =6V, TA = +25°C)Parameter Symbol ConditionsValueUnitMin Typ MaxReference voltageReference voltage

MB37889(Continued)Parameter Symbol ConditionsValuesUnitMin Typ MaxPWMcomparatorThreshold voltageVt0Duty cycle = 0 % 1.05 1.3 — VVt100Duty cycle = 100