BD9673AEFJ Datasheet, PDF (3/23 Pages) Rohm – Flexible Step-down Switching Regulators with Built-in Power MOSFET

BD9673AEFJ
Datasheet
●Description of Blocks
1. Reference
This Block generates Error Amp Standard Voltage.
Standard Voltage is 1.0V.
2. REG
This is a Gate Drive Voltage Generator and 5V Low Saturation regulator for internal Circuit Power supply.
3. OSC
This is a precise wave Oscillation Circuit with Operation Frequency fixed to 300 kHz fixed (self-running mode).
To implement the synchronization feature connect a square wave (Hi Level: higher than 2V Low Level: lower than 0.8V )
to the SYNC pin. The synchronization frequency range is 200 kHz to 500 kHz.
After connecting the rising edge of LX will be synchronized to the falling edge of SYNC pin signal after 3 count.
At the synchronization remove the external clock, the device transitions self-running mode after 7 microseconds.
4. Soft Start
A Circuit that does Soft Start to the Output Voltage of DC/DC Comparator, and prevents Rush Current during Start-up.
Soft Start Time is set at IC internal, after 10ms from starting-up EN Pin, Standard Voltage comes to 1.0V, and Output
Voltage becomes set Voltage.
5. ERROR AMP
This is an Error amplifier what detects Output Signal, and outputs PWM Control Signal.
Internal Standard Voltage is set to 1.0V. Also, C and R are connected between the Output (VC) Pin GND of Error Amp
as Phase compensation elements. (See P.11)
6. ICOMP
This is a Voltage-Pulse Width Converter that controls Output Voltage in response to Input Voltage.
This compares the Voltage added to the internal SLOPE waveform in response to the FET WS Current with Error
amplifier Output Voltage, controls the width of Output Pulse and outputs to Driver.
7. Nch FET SW
This is an internal commutation SW that converts Coil Current of DC/DC Comparator.
It contains 45V” with stand pressure” 200mΩ SW.
Because the Current Rating of this FET is 2.0A included ripple current, please use at within 2.0A.
The device has the circuit of over current protection for protecting the FET from over current.
To detect OCP 2 times sequentially, the device will stop and after 13 msec restart.
8. UVLO
This is a Low Voltage Error Prevention Circuit.
This prevents internal circuit error during increase of Power supply Voltage and during decline of Power supply Voltage.
It monitors VCC Pin Voltage and internal REG Voltage, And when VCC Voltage becomes 6.4V and below, it turns OFF
all Output FET and turns OFF DC/DC Comparator Output, and Soft Start Circuit resets.
Now this Threshold has Hysteresis of 200mV.
9. TSD
This is a Heat Protect (Temperature Protect) Circuit.
When it detects an abnormal temperature exceeding Maximum Junction Temperature (Tj=150℃), it turns OFF all
Output FET, and turns OFF DC/DC Comparator Output. When Temperature falls, it has/with Hysteresis and
automatically returns.
10. EN
With the Voltage applied to EN Pin(6pin), IC ON/OFF can be controlled.
When a Voltage of 2.0V or more is applied, it turns ON, at Open or 0V application, it turns OFF.
About 550kΩ Pull-down Resistance is contained within the Pin.
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TSZ22111・15・001
3/20
TSZ02201-0Q1Q0AJ00190-1-2
28.JAN.2014 Rev.003