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PDF MB3817 Data sheet ( Hoja de datos )
| Número de pieza | MB3817 | |
| Descripción | Switching Regulator Controller | |
| Fabricantes | Fujitsu Media Devices | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MB3817 (archivo pdf) en la parte inferior de esta página. Total 29 Páginas | ||
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FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27216-2E
ASSP For Power Supply Applications
BIPOLAR
Switching Regulator Controller
MB3817
s DESCRIPTION
The MB3817 is a pulse width modulator (PWM) type switching regulator controller IC designed for low-voltage
and high-speed operation. This can be used in applications as down-conversion or down/up-conversion (Zeta
method).
With fewer external components and faster operating speed, the MB3817 enables reduction in power supply unit
size, making it ideal for use with internal power supplies in compact, high-performance portable devices.
s FEATURES
• Wide range of operating power supply voltages: 2.5 V to 18 V
• Built-in high-precision reference voltage generator: 1.5 V ± 2%
• High speed operation is possible: Max. 500 kHz
• Wide input voltage range of error amplifier: 0 to VCC – 0.9 V
• Built-in soft start function
• Built-in timer/latch-actuated short-circuiting protection circuit
• Totem-pole type output with adjustable on/off current (for PNP transistors)
• Built-in standby function
• Small package: SSOP-16P (FPT-16P-M05)
s PACKAGE
16-pin Plastic SSOP
(FPT-16P-M05)
1 page  
MB3817
s ABSOLUTE MAXIMUM RATINGS
Parameter
Power supply voltage
Power dissipation
Storage temperature
Symbol
VCC
PD
Tstg
Condition
—
Ta +25°C
—
Min.
—
—
–55
Rating
Max.
20
440*
+125
Unit
V
mW
°C
* : The package is mounted on the epoxy board (10 cm × 10 cm).
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.
s RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Condition
Min.
Value
Typ.
Max.
Unit
Power supply voltage
VCC
— 2.5 6.0 18 V
Reference voltage output
current
IOR
—
–1 —
0 mA
Error amp. input voltage
VIN
— 0 — VCC – 0.9 V
Control input voltage
VCTL
— 0 — 18 V
Output current
IO
— 3 — 30 mA
Timing capacitance
CT
—
150
—
1500
pF
Timing resistance
RT
— 5.1 — 100 kΩ
Oscillation frequency
fOSC
— 10 200 500 kHz
Soft start capacitance
CS
— — 0.1 1.0 µF
Short detection capacitance CSCP
— — 0.1 1.0 µF
Boot capacitance
CB
— — — 0.1 µF
Operating temperature
Ta
— –40 +25 +85 °C
WARNING: Recommended operating conditions are normal operating ranges for the semiconductor device. All
the device’s electrical characteristics are warranted when operated within these ranges.
Always use semiconductor devices within the recommended operating conditions. 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 representative beforehand.
5
5 Page 
MB3817
s FUNCTIONAL DESCRIPTION
1. Switching Regulator Functions
(1) Reference voltage circuit (Ref)
The reference voltage circuit generates a temperature-compensated stable voltage (.=.1.50 V). This reference
voltage is used as the reference voltage and bias level for the power control unit.
(2) Triangular-wave oscillator circuit
By connecting a timing capacitor and a resistor to the CT (pin1) and the RT (pin2) terminals, it is possible to
generate any desired triangular oscillation waveform.
(3) Error amplifier
The error amp. is an amplifier circuit that detects the output voltage from the switching regulator and produces
the PWM control signal. The broad in-phase input voltage range of 0 V to Vcc – 0.9 V provides easy setting
from external power supplies and enables use with applications such as DC motor speed control systems.
Also, it is possible to provide stable phase compensation for a system by setting up any desired level of loop
gain, by connecting feedback resistance and a capacitor between the error amp. output pin (FB pin (pin 5))
and the inverse input pin (–IN pin (pin 4)).
(4) PWM comparator (PWM Comp.)
This is a voltage comparator with one inverted input and three non-inverted inputs, and operates as a voltage-
pulse width modulator controlling output duty in relation to input voltage.
The output transistor is turned on during the interval in which the triangular waveform is lower than any of three
voltages: the error amp. output voltage (FB pin (pin 5)), soft start set voltage (CS pin (pin 13)), or dwell time
setting voltage (DTC pin (pin 6)).
(5) Output circuits (OUT)
The output circuit has totem pole type configuration, and can drive an external PNP transistor.
The on current value can be set up to a maximum of 30 mA using the resistance (RE) connected to the VE pin
(pin 11).
The off current is set by connecting a bootstrap capacitor CB between the CP1 pin (pin 7) and CP2 pin (pin 8).
2. Power Supply Control Functions
The output is switched on and off according to the voltage level at the CTL pin (pin 15).
CTL pin voltage level
Channel on/off status
L ( 0.7 V)
Standby mode*
H ( 2.1 V)
Operating mode
* : Supply current in standby mode is 10 µA or less.
3. Protective Circuit Functions
(1) Soft start and short protection circuits (CS, SCP)
Soft starting, by preventing a rush current at power-on, can be provided by connecting a capacitor CS to the
CS pin (pin 13).
After the soft start operation is completed, the CSCP pin (pin 14) is held at “L” level (standby voltage VSTB),
which functions as short detection standby mode. If an output short causes the error amp. output to rise above
1.5 V, capacitor CSCP begins charging, and after reaching threshold voltage VTH of 0.65 V causes the OUT pin
(pin 10) to be fixed at “H” level and the dwell time to be set to 100%, and the CSCP pin (pin 14) is held at “L” level.
Once the protection circuit has been activated, the power supply must be reset to restore operation.
11
11 Page | ||
| Páginas | Total 29 Páginas | |
| PDF Descargar | [ Datasheet MB3817.PDF ] | |
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