BD9102FVM_13 Datasheet, PDF (13/29 Pages) Rohm – Synchronous Buck Converter Integrated FET

BD9102FVM BD9104FVM
2. Description of Functions
(1) Soft-Start Function
During start-up, the soft-start circuit gradually establishes the output voltage to limit the input current. This prevents the
overshoot in the output voltage and inrush current.
(2) Shutdown Function
When the EN terminal is “low”, the device operates in Standby Mode and all functional blocks, such as reference
voltage circuit, internal oscillator and drivers, are turned OFF. Circuit current during standby is 0μA (Typ).
(3) UVLO Function
The UVLO circuit detects whether the supplied input voltage is sufficient to obtain the output voltage of this IC. The
UVLO threshold, which has a hysteresis of 50mV to 300mV (Typ), prevents output bouncing.
(4) BD9102FVM BD9104FVM
tSS=1msec(Typ)
Hysteresis 100mV
VCC
EN
VOUT
Standby mode
tSS
Soft start
Operating mode
tSS
tSS
Standby
mode
Operating mode
Standby
mode
Operating mode
Standby mode
UVLO
UVLO
EN
Figure 33. Soft Start, Shutdown, UVLO Timing Chart
UVLO
(5) Short-Circuit Protection with Time Delay Function
To protect the IC from breakdown, the short-circuit protection turns the output OFF when the internal current limiter is
activated continuously for at least 1 ms. The output that is kept off may be turned ON again by restarting EN or by
resetting UVLO.
EN
VOUT
Limit
IL
Standby
mode
EN
Output OFF
latch
Operating mode
1msec
Standby
mode
Operating mode
Timer latch
EN
Figure 34. Short-Circuit Protection with Time Delay Timing Diagram
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