PLC810PG Datasheet, PDF (3/26 Pages) Power Integrations, Inc. – Continuous Mode PFC & LLC Controller Continuous Mode PFC & LLC Controller

PLC810PG
Pin Description
VCC Pins
VCC
VCC powers the small signal analog circuitry inside the IC. A
bypass capacitor must be connected from the VCC pin to the
GND pin. This capacitor needs to be a 10 mF ceramic capacitor,
or a parallel combination of a 10 mF electrolytic capacitor and a
0.1 mF ceramic capacitor.
VCCL
VCCL is the supply pin for the LLC low side driver. It powers only
the LLC low side MOSFET driver and the communications circuitry
between the analog circuitry and the LLC drivers. A 1 mF ceramic
bypass capacitor must be connected from the VCCL pin to the
GNDL pin. This capacitor provides the instantaneous current for
turning on the gate of the LLC low-side MOSFET.
VCCHB
VCCHB is the floating supply pin for the LLC high-side driver,
which is referenced to the HB pin. The HB pin is in turn
connected to the LLC MOSFET half-bridge center point. A 1 mF
ceramic bypass capacitor must be connected from the VCCHB
pin to the HB pin. This capacitor provides the instantaneous
current for turning on the gate of the high side LLC MOSFET.
In a typical application, VCC is connected to the standby
supply. VCCL should be connected to the VCC pin through a
5 W resistor for noise immunity. VCCHB is connected to the
standby supply through a series combination of a high voltage
diode and a 5 W resistor. This diode plus resistor combination
charges the 1 mF decoupling capacitor whenever the LLC low-
side MOSFET is on. The resistor limits the peak instantaneous
charging current. See R42 and D8 in Figure 4.
GND Pins
GND
GND is the return node for all analog small signals. All small
signal pin bypass capacitors must be connected to this pin via
short traces. This pin must have a single point connection, via
a dedicated trace to the PFC current sense resistor, which in
turn must be placed close to the PFC MOSFET. It must not be
connected to any other point in the PFC/LLC power train. The
VCC bypass capacitor must also be connected to this pin.
GNDP
GNDP is the return for the PFC gate drive signal only. This pin
must be connected on the PCB directly to the GND pin.
GNDL
GNDL is the return for the LLC low side gate driver only. This pin
must be connected to the LLC low side MOSFET Source pin,
with a dedicated trace, and a small ferrite bead. This pin must be
connected to the GND pin via a 1 W resistor for noise immunity.
The VCCL bypass capacitor must also be returned to this pin.
Other Pins
HB
Half-bridge pin. This pin is the return of the LLC high side
MOSFET driver. It must be connected to the center of the half-
bridge formed by the LLC MOSFETs. The VCCHB bypass
capacitor must also be returned to this pin.
ISP
Current sense, PFC. It is for sensing the negative voltage on
the current sense resistor (which describes PFC inductor
current). This sense resistor is connected between PFC
MOSFET Source and Bridge ‘-’ terminal. The signal must pass
through an RC low-pass filter with a time constant between 100
and 200 ns. The resistor must be no greater than 150 W due to
internal offset current requirements for the ISP pin. The average
inductor current (measured over several switching cycles) is
used for the PFC control algorithm. This pin also Implements
pulse-by-pulse current limiting.
ISL
Current sense, LLC. This pin is for sensing transformer primary
current, to detect LLC overload. It should be connected to the
current sense resistor, which is connected between the LLC low
side MOSFET Source pin and the bottom side of the trans-
former primary. The signal must pass through an RC low-pass
filter with a time constant between 200 ns and 1 ms. The
capacitor in the low-pass filter must be connected to the GND
pin. The current limit has 2 levels, a lower, slow current limit for
output overload, and a higher, fast current limit for component
failure protection. The series resistor in the low-pass filter
should be 1 kW or greater to limit current into the ISL pin.
GATEP
Gate drive output signal for the PFC MOSFET gate drive circuit.
GATEL
Gate drive for the low side LLC MOSFET.
GATEH
Gate drive for the high side LLC MOSFET.
VREF
3.3 V reference pin for the LLC feedback circuitry. A 1 mF
ceramic decoupling capacitor must be connected from the V_REF
pin to the GND pin.
FBP
The Feedback PFC pin is connected to the external resistor
divider that senses PFC output voltage. This is a non-inverting
input to a transconductance amplifier. The transconductance
amplifier output is connected to the VCOMP pin, to which the
feedback compensation is also connected. A 10 nF decoupling
capacitor must be connected from the FBP pin to the GND pin.
VCOMP
This pin is the connection point for PFC feedback loop
components. The voltage on this pin is used as an input to the
PFC controller multiplier. The linear voltage range for this pin is
nominally 0.5 V to 2.5 V, where higher voltage signifies less power.
FBL
LLC Feedback pin. Current entering this pin determines LLC
switching frequency. It has a Thevenin equivalent circuit of
nominally 0.65 V and 3.3 kW. FBL must be decoupled to the
GND pin with a 1 nF capacitor. Note that this capacitor forms a
pole with the input resistance.
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Rev. F 08/09