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IC Pair Exhibits Less Than 10 mW No-Load Input Power Consumption
(Power Electronics Technology Via Acquire Media NewsEdge) ON
Semiconductor's NCP1246 is a fixed-frequency current-mode
controller featuring Dynamic Self-Supply. This function greatly
simplifies the design of the auxiliary supply and the Vcc capacitor
by activating the internal startup current source to supply the
controller during start-up, transients, latch, stand-by etc. This
device contains a special HV detector which detects the application
unplug from the AC input line and triggers the X2 discharge
current. The HV structure also includes brown-out detection
circuitry.
The NCP1246 features a timer-based fault detection that ensures
the detection of overload and an adjustable power compensation to
help keep the maximum power independent of the input voltage. Due
to frequency foldback, the controller exhibits excellent efficiency
in light load condition while still achieving very low standby
power consumption. Internal frequency jittering, ramp compensation,
and a versatile latch input make this controller an excellent
candidate for robust power supply designs.
A dedicated off mode allows the SMPS to reach extremely low no
load input power consumption when combined with secondary side
controller NCP4353 or NCP4354. When used together, the SMPS is
capable of achieving <10 mW no load input power consumption. The
secondary side controller signals the NCP1246 to enter a sleep
mode, minimizing the power consumption of the control
circuitry.
The NCP4353 and NCP4354 are secondary side SMPS controllers
designed for use in applications which require extremely low no
load power consumption. The device is capable of detecting 'no
load' conditions and entering the power supply into a low
consumption OFF mode. During OFF mode, the primary side controller
is turned off and energy is provided by the output capacitors thus
eliminating the power consumption required to maintain regulation.
During OFF mode, the output voltage relaxes and is allowed to
decrease to an adjustable level. Once more energy is required, the
NCP4353 or NCP4354 automatically restarts the primary side
controller.
During normal power supply operation, the devices provide
integrated voltage feedback regulation, replacing the need for a
shunt regulator. The A versions include a current regulation loop
in addition to voltage regulation. Feedback control as well as
ONOFF signal can be provided with only one optocoupler.
The NCP4354 includes a LED driver pin implemented with an open
drain MOSFET driven by a 1 kHz square wave with a 12.5% duty cycle
for indication purpose. The NCP4354 is available in SOIC-8 package
and the NCP4353 is available in TSOP-6.
© 2012 Penton Media
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