AN8018SA Ver la hoja de datos (PDF) - Panasonic Corporation
Número de pieza
componentes Descripción
Fabricante
AN8018SA
Panasonic Corporation
AN8018SA Datasheet PDF : 26 Pages
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Voltage Regulators
AN8018SA
s Application Notes (continued)
[8] Setting of Off-terminal connection resistor
The start circuit starts its operation when Q1 is turned
on. In case of the resistor ROFF is connected externally as
shown in figure 9, the input voltage VCTL at which the start
circuit operates is obtained by the equation:
VCTL > VBEQ1 × (ROFF + R1 + R2) / R2
Therefore, ROFF can be set by:
ROFF < R2 · VCTL / VBEQ1 − R1 − R2
Set the value of ROFF according to above equations.
(Typical value)
ROFF < 25 kΩ including temperature characteristics
and sample to sample variations at VCTL = 3 V.
CTL
ROFF
Off 15
R1
30 kΩ
R2
60 kΩ
Start circuit
Q1
Figure 9. Off terminal peripheral circuit
[9] Sequential operation
In the case of sequential operation is necessary for each channel at IC operation, it is possible to turn on/off the
output of DC-DC converter individually by turning on/off Q1 and Q2 as shown in figure 10.
In the channel 1 side, if Q1 turns on and the DT1 terminal (pin 6) becomes 0.2 V or less, the output transistor turns
off due to lower voltage than the OSC terminal (pin 1). Simultaneously, unlatch circuit 1 block operates, and the timer
latch short-circuit protection does not operate because the FB1 terminal (pin 5) becomes fixed to low even if output
of channel 1 downs.
In the channel 2 side, if Q1 turns on and the DT2 terminal (pin 12) becomes 0.9 V or more, the output transistor
turns off due to higher voltage than the OSC terminal (pin 1). Simultaneously, unlatch circuit 2 block operates, and
the timer latch short-circuit protection does not operate because the FB2 terminal (pin 13) becomes fixed to high even
if output of channel 2 downs.
1.19 V
Q2
Unlatch2
0.9 V
0.9 V
Unlatch1
0.2 V
Q1
Figure 10
V2
Control block
V1
19
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