ICE2QS02G Datasheet, PDF (5/17 Pages) Infineon Technologies AG – Quasi-Resonant PWM Controller

Quasi-Resonant PWM Controller
ICE2QS02G
Pin Configuration and Functionality
1 Pin Configuration and Functionality
1.1
Pin Configuration
Pin Symbol
1
BL
2
ZC
3
FB
4
CS
5
VINS
6
GATE
7
VCC
8
GND
Function
Blanking Time
Zero Crossing
Feedback
Primary Current Sensing
Input Voltage Sensing
Gate Driver Output
Controller Supply Voltage
Controller Ground
1.2
Package
the transformer is detected when the ZC voltage falls
below V_ZCCT(100mV). Second, after the MOSFET is
turned off, an output overvoltage fault will be assumed
if V_ZC is higher than V_ZCOVP (4.5V). Finally, during the
MOSFET on time, a current depending on the main
input voltage flows out of this pin. Information on this
current is then used to adjust the maximum current
limit. More details on this function are provided in
Section 3.4.
FB (Feedback)
Usually, an external capacitor is connected to this pin
to smooth the feedback voltage. Internally, this pin is
connected to the PWM signal generator for switch-off
determination (together with the current sensing
signal), and to the digital signal processing for the
frequency reduction with decreasing load during
normal operation. Additionally, the openloop/overload
protection is implemented by monitoring the voltage at
this pin.
BL
1
ZC
2
CS (Current Sensing)
8
GND
This pin is connected to the shunt resistor for the
primary current sensing, externally, and the PWM
signal generator for switch-off determination (together
with the feedback voltage), internally. Moreover, short-
7
VCC
winding protection is realised by monitoring the V_cs
voltage during on-time of the main power switch.
FB
CS
Figure 1
3
6
GATE
4
5
VINS
Pin configuration PG-DSO-8-8 (top view)
VINS (Input Voltage Sensing)
The voltage at this pin is used for Mains Undervoltage
Protection. The protection is triggered, once V_VINS
drops below 1.25V. For a stable operation, a hysteresis
operation is ensured using an internal current source
(See Section 3.5). When the V_VINS exceeds the
hysteresis point, the system resumes its operation with
a soft-start.
1.3
Pin Functionality
BL (Adjustable Blanking Time)
By connecting a capacitor and a resistor in parallel
between this pin and the ground, the blanking time for
can be fully adjusted, as well as the restart time. This
allows the system to face a sudden power surge for a
short period of time without triggering the overload
protection. Once the protection triggered, the IC will
restart using the internal soft-start circuit, after a period
of time fixed by the external resistance and capacitor.
ZC (Zero Crossing)
Three functions are incorporated at the ZC pin. First,
during MOSFET off time, the full demagnetization of
Gate(Gate drive output)
The GATE pin is the output of the internal driver stage,
which has a rise time of 100ns and a fall time of 25ns
when driving a 2.2nF capacitive load.
VCC (Power supply)
The VCC pin is the positive supply of the IC and should
be connected to an external auxiliary supply.
GND (Ground)
This is the common ground of the controller.
Version 2.0
5
13 June 2008