BD90541MUV-C Datasheet, PDF (22/40 Pages) Rohm – Synchronous Step-Down Converter

BD90541MUV-C
Datasheet
Setting Phase Compensation Circuit
Actually, characteristics will vary depending on PCB layout, arrangement of wiring, kinds of parts used and use
conditions (temperature, etc.). Be sure to check stability and responsiveness with actual apparatus. Gain phase
analyzer or FRA is used to check frequency characteristics with actual apparatus. Contact the measurement apparatus
manufacturer for measurement method, etc. When these measurement apparatuses are not available, there is a
method of assuming margin by load response. Variation of output when the apparatus shifts from no load state to
maximum load is monitored, and it can be said that responsiveness is low if variation amount is large, and phase margin
is small if ringing occurs frequently (twice or more as a guide) after variation.
However, confirmation of quantitative phase margin is not possible.
Load
IO
Output voltage
V_O
0
Maximum load
Inadequate phase margin
Adequate phase margin.
t
Measurement of Load Response
(8) Setting the Soft Start Time
Soft start is necessary for prevention of overshoot of output voltage at startup. Soft start time varies depending on
capacitance value of capacitor connected between “SS” terminal and “GND” terminal. Set the startup time on input
voltages, VIN and PVIN, earlier than soft start time. Capacitance value of 2200pF to 0.047μF is recommended.
. _[s]
||
(9) Setting the Input filter (RIN, CIN2)
Since VIN is used as power source voltage for internal control circuit, input filter for VIN terminal is necessary in order to
prevent malfunction due to transient VIN variation. Connect RIN of 10Ω and CIN2 of 1μF. It is necessary to verify under
actual use conditions that there is no operation problem such as output off state and overshoot of output due to
reduction of VIN during transient response.
www.rohm.co.jp
© 2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
22/36
TSZ02201-0J3J0AL01140-1-2
26.Apr.2016 Rev.001