om5448 Hendon Semiconductors, om5448 Datasheet - Page 18

• Manufacturer Part Number: om5448
• Description: Low Voltage Led Driver And Boost Converter
• Manufacturer: Hendon Semiconductors

9.13
The circuit shown in figure 22 shows
how the OM5448 can generate a
regulated -5 volt supply from a single
cell battery. The pulsed signal on OP
is level shifted in a capacitor, and
rectified to provide the negative
output voltage. This output voltage is
monitored, and once it has reached
the set negative level the enable pin
EN is pulled low, disabling the
OM5448, and preventing further
charging until the voltage has fallen
back below the set negative
magnitude.
2007 May 28, Revision 1.0
Negative regulated power
supply
Fig.21 Regulated voltage multiplier boost power supply circuit using the OM5448.
9.14
As has been seen in the example
circuit above, the current flowing into
the SETI pin can be varied to give an
adjustable output from the OM5448.
This can be done mechanically by
switching in other resistances, by use
of a continuously variable
potentiometer, or via electronic
feedback to control the output power
by electronic means.
Use of pin SETI as a control
input
18
Low Voltage LED Driver
9.15
In addition to being able to vary the
output power via the SETI pin, the
enable input is also used in the circuit
above to disable the OM5448, and to
use this control input to limit the
power needs of the circuit.
and Boost Converter
Use of enable (pin EN) as a
control input
Product Specification
OM5448