|
|
PDF MB3789 Data sheet ( Hoja de datos )
| Número de pieza | MB3789 | |
| Descripción | Switching Regulator Controller | |
| Fabricantes | Fujitsu Media Devices | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MB3789 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27211-3E
ASSP For Power Supply Applications
BIPOLAR
Switching Regulator Controller
(Supporting External Synchronization)
MB3789
s DESCRIPTION
The MB3789 is a PWM (pulse width modulation) switching regulator controller supporting an external sync signal.
The MB3789 incorporates two error amplifiers which can be used respectively for voltage control and current
control, allowing the IC to serve as a DC/DC converter with current regulating functions.
The MB3789 is the ideal IC for supplying power to the back-lighting fluorescent tube for a liquid crystal display
(LCD) device such as a camera-integrated VTR.
s FEATURES
DataSheet4U.com
• Wide range of operating power supply voltages: 3 V to 18 V
• Low current consumption: 1.5 mA (Typ.)
• Wide input voltage range of error amplifier: –0.2 V to VCC – 1.8 V
• Built-in two error amplifier
• Oscillator capable of operating with an external sync signal
• Built-in timer latch short protection circuit
• Variable dead time provides control over total operating range
• Output supporting a power MOSFET
• 16-pin SSOP package mountable at high density
DataShee
s PACKAGE
16-pin Plastic SSOP
DataSheet4U.com
DataSheet4 U .com
(FPT-16P-M05)
1 page  
www.DataSheet4U.com
MB3789
et4U.com
s FUNCTIONAL DESCRIPTION
1. Switching Regulator Functions
(1) Reference voltage generator
The reference voltage generator uses the voltage supplied from the power supply pin (pin 1) to generate a
temperature-compensated, reference voltage (about 2.50 V) as the reference supply voltage for the IC’s internal
circuitry.
The reference voltage can be output, up to 50 µA, to an external device through the VREF pin (pin 2).
This regulated reference voltage can be used as the reference voltage for the switching regulator and also
used for setting the dead time.
(2) Sawtooth waveform oscillator
With a timing capacitor and a timing resistor connected to the CT pin (pin 3), the sawtooth waveform oscillator
generates a sawtooth wave which remains stable even with supply voltage variations or temperature changes.
The sawtooth wave is input to the PWM comparator. The amplitude of oscillating waveform is 0.3 V to 0.9 V.
In addition, the oscillator can be used for external synchronization, where it generates a sawtooth waveform
synchronous to the input signal from the SYNC pin (pin 4).
(3) Error amplifiers
The error amplifiers detect the output voltage from the switching regulator and outputs the PWM control signal.
Since they support a wide range of in-phase input voltages from –0.2 V to “VCC – 1.8 V”, they can be set easily
from an external power supply.
An arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the error amplifier output
pin to the inverting input pin, enabling stablDeapthaaSsheeceot4mUp.ceonmsation to the system.
The MB3789 can make a current-regulated DC/DC converter using the two internal error amplifiers respectively
for voltage control and current control.
(4) PWM comparator
The PWM comparator is a voltage comparator with one inverting input and three noninverting inputs, serving
as a voltage-pulse width converter for controlling the output duty depending on the input voltage.
The PWM comparator turns on the output transistor during the interval in which the sawtooth wave voltage
level is lower than the voltage levels at all of the error amplifier output pins, the SCP pin (pin 5), and at the
DTC pin (pin 12).
(5) Output circuit
The output circuit is a power MOSFET driven, output circuit in a totem-pole configuration. It can drive the gate
voltage up to near the supply voltage with a bootstrap capacitor connected between the OUT pin (pin 15) and
CB pin (pin 13). (See “s SETTING THE BOOTSTRAP CAPACITOR (CBS).”)
2. Protection Functions
(1) Timer-latch short-circuit protection circuit
SCP comparator 1 detects the output voltage levels of error amplifiers 1 and 2. When the output voltage level
of either (or both) of the two error amplifiers reaches 1.25 V, the timer circuit is actuated to start charging the
external protection-enable capacitor connected to the SCP pin (pin 5).
If the error amplifier output is not restored to the normal voltage level before the capacitor voltage reaches
1.8 V, the latch circuit is actuated to turn off the output transistor while making the dead time 100%.
To reset the actuated protection circuit, turn the power supply on back. (See “s SETTING THE SOFT START/
SHORT-CIRCUIT DETECTION TIME.”)
DataSheet4U.com
DataShee
DataSheet4 U .com
5
5 Page 
www.DataSheet4U.com
MB3789
Sawtooth waveform period vs.
timing capacitance characteristics
(With CT/RT oscillation)
500
VCC1 = 5 V
100 VCC2 = 6 V
50
RT = 39 kΩ
SYNC = GND
Ta = +25°C
10
5
Duty vs. sawtooth wave
frequency characteristics
(With CT/RT oscillation)
100
VCC1 = 5 V
VCC2 = 6 V
80 VDT = 0.6 V
CT = Variable
RT = 39 kΩ
SYNC = GND
60 Ta = −25°C
40
20
et4U.com
2
2 × 10 5 × 10 102 5 × 102 103
5 × 103 104
Timing capacitance CT (pF)
5 × 104
Sawtooth wave frequency vs.
ambient temperature characteristics
(With CT/RT oscillation)
0
200
500 1 k
5 k 10 k 50 k 100 k
Sawtooth wave frequency f (Hz)
500 k
Sawtooth wave frequency vs.
ambient temperature characteristics
(In external synchronization)
VCC1 = 5 V
VCC1 = 5 V
+10
VCC2 = 6 V
CT = 1500pF
+10
VCC2 = 6 V
CT = 1500pF
RT = 39
SYNC =
kGΩNDD ataSheet4U.com
RT = 43 kΩ
fSYNC = 15.0 kHz
+5 +5
00
−5 −5
−10 10
DataShee
−40 −20 0 20 40 60 80 100
Ambient temperature Ta (°C)
Gain vs. frequency and phase vs.
frequency characteristics
40
VCC1 = 5 V
180
VCC2 = 6 V
Ta = +25°C
20 Av 90
−40 −20 0 20 40 60 80 100
Ambient temperature Ta (°C)
Measurement circuit for gain-frequency
characteristics and phase-frequency characteristics
2.5 V 2.5 V
4.7 kΩ
4.7 kΩ 240 kΩ
0
−20
−40
1k
DataSheet4U.com
φ
10 k 100 k
Frequency f (Hz)
1M
0
−90
−180
10 M
10 µF
IN
4.7 kΩ
DataSheet4 U .com
4.7 kΩ
Error amp.
OUT
(Continued)
11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet MB3789.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MB3780A | Battery Backup IC |  Fujitsu |
| MB3782 | Switching Regulator Controller | Fujitsu Media Devices |
| MB3785A | Switching Regulator Controller | Fujitsu Media Devices |
| MB3788 | SWITCHING REGULATOR CONTROLLER | Fujitsu Media Devices |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |