HV9150(2013) データシートの表示（PDF） - Supertex Inc
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HV9150 Datasheet PDF : 15 Pages
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HV9150
Shutdown Timer and Timing Capacitor (CT)
A shutdown timer is also integrated into the controller for
safety purposes. When the controller shuts down from its
normal operation, the converter initial output is still at its high
level. If the feedback ground return switch is disabled at the
same time, a current path is created from the output via the
feedback resistor, and the internal protection clamping diode
at the FB pin. Depending upon the value of the FB resistor,
this momentarily conducting current can be high enough to
damage this clamping diode. In order to avoid this potential
problem, a timer is added to the disable function to keep the
feedback ground switch to the on position for a short period
of time. This on time duration is controlled by an external
capacitor CT. The larger the capacitor value is, the longer
this on time is. Its characteristic is shown in the performance
section.
Internal
Protection
Diode
FB
R2
R1
0V/3.3V
EN
Delay
FB_RTN
CT
GND
VOUT
Duty Cycle Control (VCONTROL)
The input voltage at the VCONTROL pin controls the duty
cycle of the internal oscillator output to the GATE driver. The
internal comparators are all powered by the VLL supply and
their input threshold voltages are all referenced to VLL volt-
age. A voltage divider formed by the two resistors can be
adjusted accordingly to select the desired duty cycle of the
pulse signal to the gate driver. Please see the table below.
VCONTROL
0 to 0.18VLL
0.22 to 0.38VLL
0.42 to 0.58VLL
0.62 to 0.78VLL
0.82 to 1.0VLL
VLL
VLL
Duty Cycle
0%
50%
62.5%
75%
87.5%
VCONTROL
+
Duty Cycle 87.5%
-
Internal Protection Diode at FB Pin
Hysteretic Controller Enable (EN)
The controller enable pin (EN), serves two main purposes.
The most obvious function is to turn the controller on and off,
and the other function is to act as a trigger to activate the
device to accept external voltage reference.
For any applications required a highly precise voltage
reference, an external voltage reference should be used. To
activate the device to accept the external voltage reference,
a low to high transition has to appear at the EN pin while the
voltage at the EXT_REF pin is above 0.5V.
If the system lacks enable function control, a RC circuit can
be used to mimic this function to allow the external voltage
reference.
3.3V (min)
R
EN
C
GND
Simple RC Circuit for EN Pin
Doc.# DSFP-HV9150
NR120213
7
+
Duty Cycle 75.0%
-
+
Duty Cycle 62.5%
-
+
Duty Cycle 50.0%
-
Supertex inc.
www.supertex.com
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