BD91361MUV_14 Datasheet, PDF (10/27 Pages) Rohm – Synchronous Buck Converter with Integrated FET

BD91361MUV
Datasheet
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 EN terminal is set to “Low”, the device operates in Standby Mode, and all the functional blocks such as
reference voltage circuit, internal oscillator and drivers are turned to OFF. Circuit current during standby is 0µA
(Typ).
(3) UVLO Function
This circuit detects whether the supplied input voltage is sufficient to provide the output voltage of this IC.
A hysteresis width of 50mV (Typ) is provided to prevent the output from chattering.
Hysteresis 50mV
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 24. Soft-Start, Shutdown, UVLO Timing Chart
UVLO
(4) Short-Circuit Protection with Time Delay Function
To protect the IC from breakdown, the short-circuit turns the output OFF when the internal current limiter is
activated continuously for a fixed time (tLATCH) or more. The output that is kept OFF may be turned ON again by
restarting EN or by resetting UVLO.
EN
1msec
VOUT
Limit
Output Current in non-control
1/2VOUT
Until output voltage goes up the half of
VO or over, timer latch is not operated.
(No timer latch, only limit to the output current)
Output voltage OFF Latch
IL
Output Current in control by limit value
(With fall of the output voltage, limit value goes down)
Standby Mode
EN
Operated Mode
Standby Mode
Operated Mode
Timer Latch
EN
Figure 25. Short-Circuit Protection with Time Delay Diagram
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111ï½¥15ï½¥001
10/23
TSZ02201-0J3J0AJ00200-1-2
06.Oct.2014 Rev.002