FUJITSU SEMICONDUCTOR DATA SHEET DS04-27212-3E ASSP For Power Supply Applications BIPOLAR Switching Regulator Controller (Low Voltage) MB3800 DESCRIPTION The MB3800 is a single-channel switching regulator control IC for low voltage applications incorporating a soft start function and short circuit detection function. The device has a low minimum operating voltage of 1.8 V and is ideal for the power supply of battery-operated electronic equipment. FEATURES * * * * * * * * * Wide supply voltage operating range: 1.8 V to 15 V Low current consumption: Typically 5.5 mA in operation, 1 A or less in stand-by High speed operation is possible: Maximum 1 MHz The error amplifier gain is set inside the IC, so peripheral components are minimized. Incorporates a soft start circuit. Incorporates a timer-latch type short circuit detection circuit (SCP). Totem-pole type output with adjustable on/off current (for NPN transistors) Incorporates a stand-by function. Three types of packages (SOP-8 : 2 types, SSOP-8 : 1 type) PACKAGES 8-pin Plastic SOP 8-pin Plastic SOP 8-pin Plastic SSOP (FPT-8P-M01) (FPT-8P-M02) (FPT-8P-M03) MB3800 PIN ASSIGNMENT (TOP VIEW) -IN 1 8 FB SCP 2 7 OSC V CC 3 6 GND BR/CTL 4 5 OUT (FPT-8P-M01) (FPT-8P-M02) (FPT-8P-M03) PIN DESCRIPTION 2 Pin No. Symbol I/O Description 1 -IN I 2 SCP -- Soft start and SCP setting capacitor connection pin 3 VCC -- Power supply pin 4 BR/CTL I Output current setting and control pin 5 OUT O Totem-pole type output pin 6 GND -- Ground pin 7 OSC -- Capacitor and resistor connection pin for setting the oscillation frequency 8 FB O Error amplifier output pin Error amplifier inverting input pin MB3800 BLOCK DIAGRAM V CC OSC 3 7 Reference voltage supply Sawtooth wave oscillator 0.6 V- OUT 0.1 V- 5 0.1 V 1.25 V -IN 1 - PWM 36 k + 0.5 V - Comp. + + + Error Amp. 500 30 k Output drive control circuit 0.3 V DTC 0.6 V FB 8 Soft start SCP 6 2 GND 4 SCP BR/CTL (8 pin) 3 MB3800 ABSOLUTE MAXIMUM RATINGS (Ta = +25C) Parameter Symbol Power supply voltage VCC Output source current I O+ Output sink current IO- Allowable dissipation PD Operating temperature Top Storage temperature Tstg Rating Condition Unit Min Max -- 16 V -- -50 mA -- 50 mA FPT-8P-M01, Ta +25C -- 570* mW FPT-8P-M02, Ta +25C -- 430* mW SSOP-8, Ta +25C -- 580* mW -30 +85 C -55 +125 C -- -- *: When mounted on a 10 cm square double-sided epoxy board. WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. RECOMMENDED OPERATING CONDITIONS (Ta = +25C) Parameter Symbol Value Unit Min Typ Max VCC 1.8 -- 15 V VI -0.2 -- 1.0 V VBR -0.2 -- VCC V O+ -40 -- -- mA Output sink current O- I -- -- 40 mA SCP pin capacitance CPE -- 0.1 -- F Phase compensation capacitance CP -- 0.1 -- F Output current setting resistance RB 150 390 5000 Timing resistance RT 1.0 3.0 10.0 k Timing capacitance CT 100 270 10000 pF Oscillation frequency fOSC 10 500 1000 kHz Operating temperature TOP -30 +25 +85 C Power supply voltage Error amplifier input voltage BR/CTL pin input voltage Output source current I WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device's electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within their recommended operating condition ranges. Operation outside these ranges may adversely affect reliability and could result in device failure. No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representatives beforehand. 4 MB3800 ELECTRICAL CHARACTERISTICS (VCC = +2 V, Ta = +25C) Parameter Circuit to prevent malfunction at low input voltage (U.V.L.O.) Symbol Reset voltage VR Threshold voltage VTH Condition Value Unit Min Typ Max -- -- 0.9 V 1.1 1.3 1.5 V -1.5 -1.0 -0.7 A 0.7 0.8 0.9 V -1.5 -1.0 -0.7 A 0.7 0.8 0.9 V 400 500 600 kHz -- Charging current ICS Soft start Voltage at soft start completion VtS Short circuit detection (S.C.P.) Charging current ICPC Threshold voltage VtPC Oscillation frequency fOCS RT = 3.0 k, CT = 270 pF Frequency input stability fdV VCC = 2 V to 15 V -- 2 10 % Frequency variation with temperature fdT Ta = -30C to +85C -- 5 -- % Input threshold voltage VT VFB = 450 mV 480 500 520 mV VT input stability VTdV VCC = 2 V to 15 V -- 5 20 mV VT variation with temperature VTdT Ta = -30C to +85C -- 1 -- % Input bias current IB -1.0 -0.2 1.0 A Voltage gain AV 70 100 145 V/V Frequency bandwidth BW -- 6 -- MHz 0.78 0.87 -- V -- 0.05 0.2 V -- -40 -24 A 24 40 -- A 65 75 85 % Sawtooth wave oscillator (OSC) Error amplifier Idle period adjustment section VSCP = 0 V -- VSCP = 0 V -- VIN = 0 V -- AV = 0 dB OM+ Maximum output voltage range V Output source current IOM+ -- VOM- Output sink current I Maximum duty cycle tDUTY OM- VFB = 0.45 V RT = 3.0 k, CT = 270 pF VFB = 0.8 V (Continued) 5 MB3800 (Continued) Parameter Symbol Min Typ Max 1.0 1.2 -- V VOH2 RB = 750 , VCC = 1.8 V IO = -10 mA 0.8 1.0 -- V VOL1 RB = 390 , IO = 15 mA -- 0.1 0.2 V VOL2 RB = 750 , VCC = 1.8 V IO = 10 mA -- 0.1 0.2 V Output source current IO+ RB = 390 , VO = 0.9 V -- -30 -20 mA Output sink current IO- RB = 390 , VO = 0.3 V 30 60 -- mA Pull down resistance RO 20 30 40 k Pin voltage VBR 0.2 0.3 0.4 V Input off condition IOFF -20 -- 0 A Input on condition ION -- -- -45 A Pin current range IBR -1.8 -- -0.1 mA Stand-by current ICCS BR/CTL pin open or VCC -- -- 1 A Average supply current ICC RB = 390 -- 5.5 9.3 mA -- RB = 390 -- DIAGRAM FB pin voltage Reference input for short circuit detection comparator Idle period setting voltage Sawtooth wave output Soft start setting voltage OUT pin waveforms SCP pin waveforms Soft start tS ON Power supply control SW OFF 6 Unit RB = 390 , IO = -15 mA Output section Entire device Value VOH1 Output voltage Output current setting section/ Control section Condition Output short circuit t PE Output short circuit Short circuit detection MB3800 HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION 1. Soft Start At power on, the capacitor CPE connected to the SCP pin starts charging. The PWM comparator compares the soft start setting voltage as a proportion of the voltage at the SCP pin with the sawtooth waveform. The comparison controls the ON duty of the OUT pin, causing the soft start operation. On completion of soft start operation, the voltage at the SCP pin stays low, the soft start setting voltage stays high, and the circuit enters the output short circuit detection wait state. Soft start time (The time until the output ON duty reaches approximately 50%) tS [s] 0.35 x CPE [F] 2. Short Circuit Protection If the switching regulator output suddenly drops due to load effect, the error amplifier output (FB pin) is fixed at VOM+ and capacitor CPE starts charging. When the voltage at the SCP pin reaches approximately 0.8 V, the output pin is set low and the SCP pin stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply. * Short circuit detection time tPE [s] 0.8 x CPE [F] 7 MB3800 TYPICAL CHARACTERISTICS Supply voltage vs. Supply current T a = +25C R B = 390 1.0 Input threshold voltage V T (V) 10 Supply current I CC (mA) Supply voltage vs. Input threshold voltage 8 6 4 2 0 0 4 8 12 16 0.8 0.6 0.4 0.2 0 20 T a = +25C 0 4 Supply voltage vs. Input threshold voltage 0.8 0.6 0.4 0.2 0 High level output voltage V OUT (V) T a = +25C 0 1.0 2.0 3.0 4.0 5.0 V CC = 2 V 5 0 -5 -10 -15 -40 -20 0 20 40 80 60 Low level output 1.6 1.2 0.8 0.4 -10 10 High level output V CC = 2 V R B = 390 T a = +25C 0 -20 -30 20 Ambient temperature vs. Input threshold voltage variation ratio Ambient temperature T a (C) 2.0 0 16 Supply voltage V CC (V) -40 High level output current I OUT (mA) -50 Low level output voltage V OUT (mV) Input threshold voltage V T (V) 1.0 12 Supply voltage V CC (V) Input threshold voltage variation ratio V T/V T (%) Supply voltage V CC (V) 8 100 V CC = 2 V R B = 390 T a = +25C 500 400 300 200 100 0 0 20 40 60 80 100 High level output current I OUT (mA) (Continued) 8 MB3800 (Continued) BR/CTL pin current vs. BR/CTL pin voltage -50 500 BR/CTL pin voltage V BR (mV) Output source current I OUT (mA) BR/CTL pin current vs. Output source current -40 V CC = 2 V V OUT = 0.9 V T a = +25C -30 -20 -10 0 -0.4 0 -0.8 -1.2 -1.6 400 300 200 100 0 -2.0 V CC = 2 V T a = +25C 0 -0.4 BR/CTL pin current I BR (mA) -0.8 -1.2 -1.6 -2.0 BR/CTL pin current I BR (mA) Timing resistor vs. Oscillation frequency BR/CTL pin current vs. Supply current 1M V CC = 2 V T a = +25C Oscillation frequency f OSC (Hz) Supply current I CC (mA) 5.0 4.0 3.0 2.0 1.0 0 -20 0 -40 -60 -80 500 k 200 k C T = 1000 pF 100 k 50 k 20 k C T = 10000 pF 10 k 5k 2k 1k -100 BR/CTL pin current I BR (A) 10 k 5k 20 k Ambient temperature vs. Frequency variation ratio 10 10 C T = 270 pF R T = 3.0 k Ta = +25C 5 Frequency variation ratio f/f (%) Frequency variation ratio f/f (%) 2k Timing resistor R T () Supply voltage vs. Frequency variation ratio 0 -5 -10 -15 V CC = 2 V T a = +25C C T = 100 pF 0 2 4 6 8 10 12 Supply voltage V CC (V) 14 16 V CC = 2 V C T = 270 pF R T = 3.0 k 5 0 -5 -10 -15 -40 -20 0 20 40 60 80 100 Ambient temperature T a (C) (Continued) 9 MB3800 (Continued) Oscillation frequency vs. Maximum duty cycle V CC = 2 V C T = 270 pF Ta = +25C Maximum duty cycle t DUTY (%) 100 80 60 40 20 0 10 K 100 K 1M Oscillation frequency f OSC (Hz) Output pin voltage and current waveforms (reference data) 2V (V) 6 V CC = 2 V C T = 270 pF R T = 1.0 k 4 V OUT 2 0 (mA) 50 I OUT 0 -50 10 mV 0 200 ns 0.4 0.8 1.2 1.6 2.0 t (s) Note: The OFF delay time of V OUT depends on the characteristics of the external transistor. Measurement circuit diagram V CC (5 V) 22 H 18 k MB3800 5 I OUT V OUT 10 F 4 2 k 390 -IN 10 MB3800 FUNCTIONAL DESCRIPTION 1. Switching Regulator Function (1) Reference voltage circuit The reference voltage circuit generates a temperature-compensated reference voltage (1.25V) from voltage supplied from the power supply pin (pin 3). In addition to providing the reference voltage for the switching regulator, the circuit also sets the idle period. (2) Sawtooth wave oscillator The sawtooth oscillator generates a sawtooth wave (up to 1 MHz) that is stable with respect to the supply voltage and temperature. The capacitor and resistor that set the oscillation frequency are connected to the OSC pin (pin 7). (3) Error amplifier (Error Amp.) The error amplifier detects the output voltage of the switching regulator and outputs the PWM control signal. The voltage gain is fixed, and connecting a phase compensation capacitor to the FB pin (pin 8) provides stable phase compensation for the system. (4) PWM comparator (PWM Comp.) The voltage comparator has one inverting and three non-inverting inputs. The comparator is a voltage/pulse width converter that controls the ON time of the output pulse depending on the input voltage. The output level is high (H) when the sawtooth wave is lower than the error amplifier output voltage, soft start setting voltage, and idle period setting voltage. (5) Output circuit The output circuit has a totem pole type configuration and can drive an external NPN transistor directly. The value of the ON/OFF current can be set by a resistor connected to the BR/CTL pin (pin 4). 2. Power Supply Control Function Stand-by mode (supply current 1 A or less) can be set by connecting the BR/CTL pin (pin 4) to VCC or by making the pin open circuit. SW Mode OFF Stand-by mode ON Operating mode MB3800 4 BR/CTL RB SW 11 MB3800 3. Other Functions (1) Soft start and short circuit detection Soft start operation is set by connecting capacitor CPE to the SCP pin (pin 2). Soft start prevents a current spike on start-up. On completion of soft start operation, the SCP pin (pin 2) stays low and enters the short circuit detection wait state. When an output short circuit occurs, the error amplifier output is fixed at VOM+ and capacitor CPE starts charging. After charging to approximately 0.8 V, the output pin (pin 5) is set low and the SCP pin (pin 2) stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply. (See " HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION".) (2) Circuit to prevent malfunction at low input voltage Transients when powering on or instantaneous glitches in the supply voltage can lead to malfunction of the control IC and cause system damage or failure. The circuit to prevent malfunction at low input voltage detects a low input voltage by comparing the supply voltage to the internal reference voltage. On detection, the circuit fixes the output pin to low. The system recovers when the supply voltage rises back above the threshold voltage of the malfunction prevention circuit. APPLICATION EXAMPLE 18 k 22 H -IN SCP V in (3 V) 1 8 2 7 FB OSC MB3800 V CC 3 6 BR/CTL 4 0.1 F 5 33 F 390 2 k 10 F GND OUT 0.1 F 270 pF 3 k CTL 12 Vo (5 V) MB3800 NOTES ON USE * Take account of common impedance when designing the earth line on a printed wiring board. * Take measures against static electricity. - For semiconductors, use antistatic or conductive containers. - When storing or carrying a printed circuit board after chip mounting, put it in a conductive bag or container. - The work table, tools and measuring instruments must be grounded. - The worker must put on a grounding device containing 250 k to 1 M resistors in series. * Do not apply a negative voltage - Applying a negative voltage of -0.3 V or less to an LSI may generate a parasitic transistor, resulting in malfunction. ORDERING INFORMATION Part number Package MB3800PF 8-pin Plastic SOP (FPT-8P-M01) MB3800PNF 8-pin Plastic SOP (FPT-8P-M02) MB3800PFV 8-pin Plastic SSOP (FPT-8P-M03) Remarks 13 MB3800 PACKAGE DIMENSIONS Note 1) Note 2) Note 3) Note 4) 8-pin Plastic SOP (FPT-8P-M01) +0.25 *1 : These dimensions include resin protrusion. *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder. +.010 +0.03 *1 6.35 -0.20 .250 -.008 0.17 -0.04 +.001 8 .007 -.002 5 *2 5.300.30 7.800.40 (.209.012) (.307.016) INDEX Details of "A" part +0.25 2.00 -0.15 +.010 .079 -.006 1 1.27(.050) "A" 4 0.470.08 (.019.003) 0.13(.005) (Mounting height) 0.25(.010) 0~8 M 0.500.20 (.020.008) 0.600.15 (.024.006) +0.10 0.10 -0.05 +.004 .004 -.002 (Stand off) 0.10(.004) C 2002 FUJITSU LIMITED F08002S-c-6-7 Dimensions in mm (inches) . Note : The values in parentheses are reference values. (Continued) 14 MB3800 Note 1) Note 2) Note 3) Note 4) 8-pin Plastic SOP (FPT-8P-M02) +0.25 *1 : These dimensions include resin protrusion. *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder. +.010 +0.03 *1 5.05 -0.20 .199 -.008 0.22 -0.07 +.001 .009 -.003 8 5 *2 3.900.30 6.000.40 (.154.012) (.236.016) Details of "A" part 45 1.550.20 (Mounting height) (.061.008) 0.25(.010) 0.40(.016) 1 "A" 4 1.27(.050) 0.440.08 (.017.003) 0.13(.005) 0~8 M 0.500.20 (.020.008) 0.600.15 (.024.006) 0.150.10 (.006.004) (Stand off) 0.10(.004) C 2002 FUJITSU LIMITED F08004S-c-4-7 Dimensions in mm (inches) . Note : The values in parentheses are reference values. (Continued) 15 MB3800 (Continued) Note 1) Note 2) Note 3) Note 4) 8-pin Plastic SSOP (FPT-8P-M03) *1 : Resin protrusion. (Each side : +0.15 (.006) Max) . *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder. +0.03 *1 3.500.10(.138.004) 0.17 -0.04 +.001 8 .007 -.002 5 *2 4.200.10 6.200.20 (.165.004) (.244.008) INDEX Details of "A" part +0.20 1.25 -0.10 +.008 .049 -.004 (Mounting height) 0.25(.010) 1 "A" 4 0.80(.031) 0.370.08 (.015.003) 0.10(.004) 0~8 M 0.500.20 (.020.008) 0.600.15 (.024.006) 0.100.10 (.004.004) (Stand off) 0.10(.004) C 2002 FUJITSU LIMITED F08005S-c-3-5 Dimensions in mm (inches) . Note : The values in parentheses are reference values. 16 MB3800 FUJITSU LIMITED All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU sales representatives before ordering. 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