BD9123MUV_11 Datasheet, PDF (9/18 Pages) Rohm – Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET

BD9123MUV
Technical Note
●About setting the output voltage
Output voltage shifts step by step as often as bit setting to control the overshoot/undershoot that happen when changing the
setting value of output voltage. From the bit switching until output voltage reach to setting value, 8 steps (max) delay will
occur.
VID<2:0>
(0,0,1)
(1,1,1)
1.2V
VOUT
0.85V
tVID (max)=0.06ms
ⅰ) Switching 3 bit synchronously
VID<2>
VID<1>
VID<0>
Count STOP
VOUT
5µs(max)
About 10µs from bit switching
ⅱ) Switching 3 bit with the time lag
VID<2>
VID<1>
VID<0>
ⅲ) Switching the bit during counting
V2D〈2〉
〈1〉
〈0〉
Count STOP
VOUT
About 10µs from bit switching
Count STOP
VOUT
About 10µs from switching the last bit
Fig.31 Timing chart of setting the output voltage
It is possible to set output voltage, shown the diagram 1 below, by setting VID<0>～<2> 0 or 1.
VID<2:0> terminal is set to VID<2:0>=(0,0,0) originally by the pull down resistor with high impedance inside IC.
By pulling up/ pulling down about 10kΩ, the original value is changeable optionally.
Table of output voltage setting
VID<2>
VID<1>
VID<0>
VOUT
0
0
0
1.0V
0
0
1
0.85V
0
1
0
0.9V
0
1
1
0.95V
1
0
0
1.05V
1
0
1
1.1V
1
1
0
1.15V
1
1
1
1.2V
*After 10µs(max) from the bit change, V_OUT change starts.
*Requiring time for one step (50 mV shift) of V_OUT is 5µs(max).
*From the bit switching until output voltage reach to setting value, tVID(max)=0.06ms delay will occur.
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2011.01 - Rev.A