SWITCHING REGULATOR CONTROLLER MB3788 DESCRIPTION 24-PI

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SWITCHING REGULATOR CONTROLLER MB3788 DESCRIPTION 24-PI

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DS04-27209-1E
SWITCHING REGULATOR CONTROLLER
MB3788
DESCRIPTION
24-PIN PLASTIC SSOP
MB3788 dual-channel PWM-type switching regulator controller; incorporates reference voltage. MB3788 circuit output circuit well reference voltage power supply with voltage accuracy ±1%. maximum operating frequency MHz. designed voltage-drop output switching regulator suitable logic power supply speed control motor. MB3788 compatible with master producing triangular waves, sawtooth waves sine waves with amplitude used high-performance portable equipment such video camcorder notebook personal computer (word processor).
FEATURES
Wide operating power supply voltage range: power dissipation Operating: (standard) Standby: max. High-frequency operation: On-chip timer latch-type short-circuit detection circuit Wide error amplifier input voltage range: -0.2 On-chip high-accuracy reference voltage circuit: 2.50 Output circuit transistor drive output pin: Push-pull type ON/OFF current values independently On-chip standby function output control function High-density packaging: SSOP-24P
This device contains circuitry protect inputs against damage high static voltages electric fields. However, advised that normal precautions taken avoid application voltage higher than maximum rated voltages this high impedance circuit.
(FPT-24P-M03)
MB3788
ASSIGNMENT
(TOP VIEW) VCC(out) OUT1 -IN1(E) +IN1(E) -IN1(C) -IN(PWN) VREF (FPT-24P-M03) OUT2 -IN2(E) +IN2(E) -IN2(C) CTL2 CTL1
MB3788
DESCRIPTION
Channel Channel Control circuit name OUT1 -IN1(E) +IN1(E) -IN1(C) -IN2(C) +IN2(E) -IN2(E) OUT2 CTL1 Descriptions
Channel push-pull type output Channel output current setting Channel output transistor current setting: Output transistor current connecting capacitor between pins Cb1. Channel error amplifier output Channel error amplifier inversion input Channel error amplifier non-inversion input Channel comparator inversion input Channel comparator inversion input Channel error amplifier non-inversion input Channel error amplifier inversion input Channel error amplifier output Channel output transistor current setting: Output transistor current connecting capacitor between pins Cb2. Channel output current setting Channel push-pull type output Power channel control level: Power channel operating level: Standby Channel control When CTL1 level, level: Channel operating level: Channel Short-circuit protection circuit capacitor connection Output circuit power Master oscillating waveform input Reference power control circuit power Reference voltage output Ground
CTL2 VCC2 -IN(PWM) VCC1 VREF
Power circuit
Note:
alphabetic characters parenthesis above indicate following input pins. (C): Comparator (E): Error amplifier
MB3788
BLOCK DIAGRAM
Channel
+IN1 -IN1
Error amplifier comparator
current setting
VCC(out)
OUT1
-IN1
Comparator
Channel
+IN2 -IN2
Error amplifier comparator
current setting
OUT2
-IN2
Comparator
Timer circuit
comparator
CTL2
VREF latch circuit input voltage protection circuit
Reference Power/channel ON/OFF voltage circuit power (2.5
CTL1
-IN(PWM)
VREF
MB3788
FUNCTIONAL DESCRIPTION
Major Functions
Reference voltage power circuit
reference voltage power supply produces reference voltage 2.50 which temperature-compensated voltage supplied from power (pin 11); used internal circuit operating power supply. reference voltage also output externally from VREF (pin12).
Error amplifier
error amplifier detects switching regulator output voltage outputs control signal. wide in-phase input voltage range -0.2 make setting from external power supply easy. Connecting output inversion input error amplifier through feedback resistor capacitor allows setting loop gain provide stable phase compensation.
comparator
comparator controls output pulse time according input voltage. voltage input (PWM) turns output transistor when lower than output voltage error amplifier.
Output circuit
output circuit configured push-pull form uses transistor drive system drive transistor (See Output Current.)
Channel Control Function
Channels ON/OFF combining voltage levels CTL1 (pin CTL2 (pin 14).
Channel ON/OFF Setting Conditions
Voltage level CTL1 CTL2
Channel ON/OFF status Power circuit Channel Stand state* Channel
*The power current standby state max.
MB3788
Protection Functions
Timer latch-type short-circuit protection circuit
comparator detects output voltage levels comparators detect output short circuit. output voltage comparator increases transistor timer circuit turned short circuit protection capacitor connected externally (pin starts charging. latch circuit turns output transistor simultaneously clears duty cycle when output voltage level comparator does return normal voltage level until capacitor voltage rises base-emitter junction voltage 0.65 transistor. (See Time Constant Timer Latch-Type Short-Circuit Protection Circuit.) When protection circuit operates, recycle power reset circuit.
input voltage malfunction fail-safe circuit
transient power-on, instantaneous supply voltage drop cause control malfunction, which damage system. input voltage malfunction fail-safe circuit detects internal reference voltage level based supply voltage level, resets latch circuit, turns output transistor, clears duty cycle holds (pin level. circuits recovered when supply voltage greater than threshold voltage fail-safe circuit.
MB3788
ABSOLUTE MAXIMUM RATINGS
+25°C) Parameter Symbol VICTL Tstg Conditions
Ratings 500* +125
Unit
Supply voltage Control input voltage Allowable loss Operating ambient temperature Storage temprature
+25°C
Value obtained when mounted double-sided epoxy substrate
RECOMMENDED OPERATING CONDITIONS
+25°C) Parameter Symbol VICTL fosc Conditions Values Min. -0.2 -0.2 -0.2 Typical Max. 1000 Unit
Supply voltage Reference voltage output curren Error amplifier input voltage Error amplifier input voltage Control input voltage Output current Operating frequency Operating ambient temperature
MB3788
ELECTICAL CHARACTERISTICS
(VCC =6V, +25°C) Value Parameter Reference voltage Output voltage temperature variation Input stability Load stability Short-circuit output current Symbol VREF VREF/ VREF Line Load Conditions Min. -30° +85°C -0.1 VREF 2.475 0.58 -200 -0.2 0.60 -1.4 -100 -200 -0.2 VREF-0.3 Typical 2.500 ±0.2 2.65 2.45 0.65 -100 0.65 -1.0 0.05 Max. 2.525 0.72 VCC-1.8 0.70 -0.6 VCC-1.8 Unit
Reference voltage
voltage malfunction fail-safe circuit
Threshold voltage Hysteresis width Reset voltage VHYS VICM VtPC VSTB IIbpc VICM CMRR VOM+ Maximum output voltage width VOMOutput sink current Output source current IOM+ IOM-
Short-circuit detection comparator
Input offset voltage Input bias current In-phase input voltage range Threshold voltage
Short-circuit detector
Input standby voltage Input latch voltage Input source current Input offset voltage Input offset current Input bias current In-phase input voltage range Voltage gain
Error amplifier
Frequency bandwidth In-phase signal rejection ratio
MB3788
Values Parameter
Threshold voltage Vt100 comparator Input sink current Input source current Input bias current Threshold voltage Control Input current Source current Output Sink curren Output leak current Standby current devices Power current output ICCO VCTL IIM+ IIMIIB VCTL Duty cycle -1.0 -0.5 2.25
Symbol
Conditions
Duty cycle
Min.
1.05
Typical
Max.
Unit
MB3788
STANDARD CHARACTERISTIC CURVES
Power current supply voltage characteristic CTL1, Power current (mA) Supply voltage 3.Reference voltage, output current setting voltage supply voltage characteristic +25°C Output current setting voltage Supply voltage Reference voltage control voltage characteristic +25°C Control current control voltage characteristic +25°C Reference voltage VREF +25°C CTL1 Reference voltage supply voltage characteristic +25°C
Supply voltage Reference voltage ambient temperature characteristic 2.56 Reference 2.54 voltage VREF 2.52 2.50 2.48 2.46 2.44 Ambient temperature (°C) VCTL1,
Reference voltage VREF
VREF
Reference voltage VREF
Control current lCTL1 (µA)
Control voltage VCTL1
Control voltage VCTL1
MB3788
Duty input oscillating frequency characteristic Input waveform K100 K500 Input oscillating frequency (Hz) 1.9V 1.3V +25°C
8.Gain frequency characteristic phase frequency characteristic +25°C Phase (deg) -180 K100 (Hz)
Duty
Gain (dB)
Power dissipation ambient temperature characteristic 1000 Circuit measuring gain frequency characteristic phase frequency characteristic Power dissipation (mW) Error amplifier
4060 Ambient temperature (°C)
MB3788
OUTPUT VOLTAGE
VREF VOUT VOUT VREF
Note: output voltage positive range (VOUT
MB3788
OUTPUT CURRENT
output circuit configured push-pull type shown Figure current value output current waveform shown Figure constant current value time constant. Each output current calculated from following expression: current 1.5/RE (Output current setting voltage: current time constant proportional value
Drive current
current setting part
current
Output current current
current
Fig.1 Output Circuit Diagram
Fig.2 Output Current Waveform
1000
Vout
-IN1
Iout MB3788 1000
-IN1
Fig.3 Output Voltage Current Waveforms (Channel
Fig.4 Measurement Circuit Diagram
MB3788
TIME CONSTANT TIMER LATCH-TYPE SHORT-CIRCUIT PROTECTION CIRCUIT
load conditions switching regulator stable, outputs comparators change, comparator outputs High level. this time, (pin held about load conditions change suddenly load short-circuit, example, output voltage comparator channel becomes High-level signal (more than Then, comparator outputs level transistor turned off. short-circuit protection capacitor externally connected starts charge. 10-6/CPE 0.65 10-6/CPE /0.6 Once capacitor charged about 0.65 latch output drive transistor turned off. this time, duty cycle made output voltage (pin held level. This closes latch input discharge CPE.
input voltage comparator protection circuit
Comparator Comparator
latch-type circuit
Fig. Latch-Type Short-Circuit Protection Circuit
MB3788
PROCESSING WITHOUT USING
timer latch-type short-circuit protection circuit used, connect (pin close possible. Also, connect input each channel comparator (pin 11).
-IN1
-IN2
Fig. Processing without using
MB3788
EQUIVALENT SERIES RESISTANCE SMOOTHING CAPACITOR STABILITY DC/DC CONVERTER
equivalent series resistance (ESR) smoothing capacity DC/DC converter great effect loop phase characteristics. causes small delay capacitor with series resistance (Figures thus improving system stability. other hand, using smoothing capacitor with reduces system stability. Therefore, attention should paid using semiconductor electrolytic capacitors (such capacitors) tantalum capacitors with (Phase margin reduction using capacitor explained next page.)
Fig. Basic Voltage-Drop Type DC/DC Converter Circuit
Gain (dB) (1): (2): Phase (deg) (1): (2): -180
101001 k100 Frequency (Hz)
101001 k100 Frequency (Hz)
Fig.8 Gain Frequency Characteristic
Fig.9 Phase Frequency Charecteristic
MB3788
(Reference Data) phase margin halved changing smoothing capacitor from aluminum electrolytic capacitor semiconductor electrolytic capacitor capacitor: with (Figures 12).
VOUT
VREF/2 Error amplifier
characteristic between VOUT
Fig. DC/DC Converter Characteristic Measurement Diagram
Aluminum electrolytic capacitor gain frequency phase frequency characteristics (DC/DC converter output) Gain (dB) Phase (deg) 101001 Frequency (Hz) Fig. Gain Frequency Characteristic -180 Aluminum electrolytic capacitor fOSC
capacitor gain frequency phase frequency characteristics (DC/DC converter output) Gain (dB) 101001 Frequency (Hz) Fig.12 Phase Frequency Characteristic Curves Phase (deg) capacitor fOSC
-180
MB3788
APPLICATION CIRCUIT
CTL1 CTL2
+IN1
<Logic power supply> 1000
-IN1
0.22
Channel (dB)
VCC(out) OUT1
-IN1
<Logic power supply> +IN2
1000
-IN2
0.22
Channel (deg)
OUT2
-IN2
VREF
-IN(PWM)
Triangular wave signal
<Analog power supply> <Sensor power supply> <MB3785A-used DC/DC converter> motor speed control> motor speed control>
motor motor
MB3788
PRECAUTIONS
apply voltage greater than maximum rating, damaged. MB3788 under recommended operating conditions. voltage greater than maximum voltage applied, electrical characteristics guaranteed; voltage smaller than minimum voltage applied, operation will become unstable. ground board, thickest cable possible because high frequencies used which easily produce high-frequency noise. Connecting unused channel unused channels, output voltage comparator detecting short-circuit must fixed level. Take measures against static electricity. Carry semiconductors conductive container anti-static case. Carry board conductive container stored transported after packaging. Ground workbench, tools measuring instruments. Workers should grounded through resistance
MB3788
FUJITSU LIMITED
further information please contact:
Japan FUJITSU MEDIA DEVICES LIMITED Marketing Technical Support Dept. HAMADA BLDG 1-19-20, Shin-yokohama kouhoku-ku Yokohama-shi Kanagawa 222-0033, Japan Tel: 81(45) 471-0061 Fax: 81(45) 471-0076
Rights Reserved. contents this document subject change without notice. Customers advised consult with FUJITSU sales representatives before ordering. information circuit diagrams this document presented examples semiconductor device applications, intended incorporated devices actual use. Also, FUJITSU unable assume responsibility infringement patent rights other rights third parties arising from this information circuit diagrams. FUJITSU semiconductor devices intended standard applications (computers, office automation other office equipment, industrial, communications, measurement equipment, personal household devices, etc.). CAUTION: Customers considering products special applications where failure abnormal operation directly affect human lives cause physical injury property damage, where extremely high levels reliability demanded (such aerospace systems, atomic energy controls, floor repeaters, vehicle operating controls, medical devices life support, etc.) requested consult with FUJITSU sales representatives before such use. company will responsible damages arising from such without prior approval. semiconductor devices have inherent chance failure. must protect against injury, damage loss from such failures incorporating safety design measures into your facility equipment such redundancy, fire protection, prevention over-current levels other abnormal operating conditions. products described this document represent goods technologies subject certain restrictions export under Foreign Exchange Foreign Trade Japan, prior authorization Japanese government will required export those products from Japan.
North South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street Jose, 95134-1804, Tel: (408) 922-9000 Fax: (408) 922-9179 Customer Response Center Mon. Fri.: (PST) Tel: (800) 866-8608 Fax: (408) 922-9179
http://www.fujitsumicro.com/
Europe FUJITSU MIKROELEKTRONIK GmbH Siebenstein 6-10 D-63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122
http://www.fujitsu-ede.com/
Asia Pacific FUJITSU MICROELECTRONICS ASIA #05-08, Lorong Chuan Tech Park Singapore 556741 Tel: (65) 281-0770 Fax: (65) 281-0220
http://www.fmap.com.sg/
F9902 FUJITSU LIMITED Printed Japan

SWITCHING REGULATOR CONTROLLER MB3788 DESCRIPTION 24-PI

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