BD8964FVM-TR Ver la hoja de datos (PDF) - ROHM Semiconductor
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BD8964FVM-TR Datasheet PDF : 25 Pages
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BD8964FVM
Datasheet
Application Information
1. Operation
BD8964FVM is a synchronous step-down switching regulator that achieves fast transient response by employing current
mode PWM control system.
(1) Synchronous Rectifier
Integrated synchronous rectification using two MOSFETS reduces power dissipation and increases efficiency when
compared to converters using external diodes. Internal shoot-through current limiting circuit further reduces power
dissipation.
(2) Current Mode PWM Control
The PWM control signal of this IC depends on two feedback loops, the voltage feedback and the inductor current
feedback.
(a) PWM (Pulse Width Modulation) Control
The clock signal coming from OSC has a frequency of 1Mhz. When OSC sets the RS latch, the P-Channel
MOSFET is turned on and the N-Channel MOSFET is turned OFF. The opposite happens when the current
comparator (Current Comp) resets the RS latch i.e. the P-Channel MOSFET is turned OFF and the N-Channel
MOSFET is turned on. Current Comp’s output is a comparison of two signals, the current feedback control
signal “SENSE” which is a voltage proportional to the current IL, and the voltage feedback control signal, FB.
VOUT
SENSE
Current
Comp
RESET
Level
RQ
Shift FB
Gm Amp
SET S
RITH
OSC
Driver
Logic
IL
SW
Load
VOUT
Figure 18. Diagram of Current Mode PWM Control
Current
Comp
SET
RESET
SW
IL
PVCC
SENSE
FB
GND
GND
GND
IL(AVE)
VOUT
VOUT(AVE)
Figure 19. PWM Switching Timing Diagram
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