SI9138 Datasheet, PDF (9/14 Pages) Vishay Siliconix – Multi-Output, Individual On/Off Control Power-Supply Controller

New Product
Si9138
Vishay Siliconix
TIMING DIAGRAMS
ON 3 or ON 5
V_IN
V_L
V_REF
OSC EN
(Sysmon EN)
OSC
2.4 V
f_max (SS)
DH
t_BBM
4 ms
The converter is enabled
V_IN is applied
LDO is activated after V_IN is
applied
REF circuit is activated after V_L
becomes available
After V_REF goes above 2.4 V,
the converter is turned on
Oscillator is activated
Slow soft-start gradually increases
the maximum inductor current
High-side gate drive duty ratio
gradually increases to maximum
D_L
Low-side gate drive
FIGURE 2. Converter is Enabled Before V_IN is Applied, 3.3 V or 5 V controllers
ON 3 or ON 5
V_IN
V_L
V_REF
OSC EN
(Sysmon EN)
OSC
f_max (SS)
DH
2.4 V
4 ms
The converter is enabled
V_IN is applied
LDO is activated after V_IN is
applied
REF circuit is activated after V_L
becomes available
After V_REF goes above 2.4 V,
the converter is turned on
Oscillator is activated
Slow soft-start gradually increases
the maximum inductor current
DL
FIGURE 3. Converter is Enabled After V_IN is Applied, 3.3 V or 5 V Controllers
Document Number: 71446
S-20642—Rev. B, 13-May-02
www.vishay.com
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