Si9139 Datasheet, PDF (15/17 Pages) Vishay Siliconix – Multi-Output, Individual On/Off Control Power-Supply Controller

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DETAILED FUNCTIONAL BLOCK DIAGRAMS
5-V
V_IN
Linear
Regulator
V_L
ON_A
ON_B
4V
3.3-V
Reference
2.4 V
Reset
Handler
FIGURE 7. Complete Si9139 Block Diagram
Si9139
Vishay Siliconix
Enable
A
SMPS
Controller
Good A
Enable
B
SMPS
Controller
Good B
Enable
Auxiliary
1.2- to 20-V
Adjustable
Buck-Boost
Controller
C
FB_A
CS_A
BST_A
DH_A
LX_A
DL_A
FB_B
CS_B
BST_B
DH_B
LX_B
DL_B
FB_C
CSP
CSN
BST_C
DH_C
LX_C
DL_C
RESET
DESCRIPTION OF OPERATION
Shutdown Mode
The logic threshold for the ON_A and ON_B pins is 1.6 V. Input
voltage must be 0.8 V or less for logic low and 2.4 V or higher
for logic high.
Start-up Sequence
Start-up is controlled by individual ON/OFF control. The A
output is controlled by ON_A whilst the B and the C adjustable
outputs are both controlled by ON_B.
When both the A and B SMPS outputs are within tolerance and
32,000 clock cycles (typically equal to 107 ms) have elapsed
since the second SMPS output went into regulation, the
RESET pin will go high, signifying that all converters are
operating correctly (see RESET Power Good Voltage
Monitor).
The Si9139 converts a 4.5-V to 30-V input voltage to five
different output voltages; two buck (step-down) high current,
PWM, switch-mode supplies of 1.5-V to 3.3-V, one
“Buck-Boost” PWM switch-mode supply adjustable from
1.24 V to 20 V, one precision 3.3-V reference and one 5-V low
drop out (LDO) linear regulator output. Switch-mode supply
output current capabilities depend on external components
(can be selected to exceed 10 A). In the standard application
circuit illustrated in Figure 1, each buck converter is capable of
delivering 5 A, with the buck-boost converter delivering
500 mA.
Document Number: 71841
S-22317—Rev. A, 16-Dec-02
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