ICE2QS01 Infineon Technologies, ICE2QS01 Datasheet - Page 8

• Manufacturer Part Number: ICE2QS01
• Description: IC PWM CONTROLLER 8DIP
• Manufacturer: Infineon Technologies
• Type: Quasi-resonant PWM Controllerr

Specifications of ICE2QS01

• Package / Case: 8-DIP (0.300", 7.62mm)
• Frequency - Switching: 80kHz
• Current - Startup: 300µA
• Voltage - Supply: 11 V ~ 25 V
• Operating Temperature: -25°C ~ 125°C
• Mounting Type: Through Hole
• Switching Frequency: 80 KHz
• Maximum Operating Temperature: + 125 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Mode: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: SP000269328

controller is implemented to avoid mistriggering by the
ring after MOSFET is turned off. Functionality of these
parts is described as in the following.
3.3.1.1
The up/down counter stores the number of zero
crossing to be ignored before the main power switch is
switched on after demagnetisation of the transformer.
This value is a function of the regulation voltage, which
contains
Generally, a high output power results in a high
regulation voltage. According to this information, the
value in the up/down counter is changed to a low value
in case of high regulation voltage, and to a high value
in case of low regulation voltage. In ICE2QS01, the
lowest value of the counter is 1 and the highest 7.
Following text explains how the up/down counter value
changes in responding to the regulation voltage v
The regulation voltage v
three thresholds V
results, the value in the up/down counter is changed,
which is summarised in Table 1 and Figure 4
respectively.
Table 1
Figure 4
According to the comparison results the up/down
counter counts upwards, keeps unchanged or counts
downwards. However, the value in up/down counter is
Version 2.1
always lower than V
always lower than V
v
Always lower than V
Once higher than V
Once higher than V
Once higher than V
REG
Case 1
Case 2
Case 3
clock
V
V
V
V
RM
FB
RH
RL
information
Up/down Counter
4
2
7
Operation of the up/down counter
Up/down counter operation
5
3
7
6
4
7
RL
, V
RH
RM
RL
RH
RM
RL
6
4
7
, but
, but
REG
RH
about
6
4
7
T=48ms
and V
is internally compared with
6
4
7
the
up/down counter
action
Count upwards till
7
Stop counting, no
value changing
Count downwards
till 1
Set up/down
counter to 1
RM
5
3
6
. According to the
4
2
5
output
3
1
4
1
1
1
1
power.
t
t
REG
.
8
limited between 1 and 7. If the counter tends to count
beyond this range, the attempt is ignored.
In normal case, the up/down counter can only be
changed by one each time at the clock period of 48ms.
However, to ensure a fast response to sudden load
increase, the counter is set to 1 in the following
switching period after the regulation voltage v
exceeds the threshold V
3.3.1.2
In the system, the voltage from the auxiliary winding is
applied to the zero-crossing pin through a RC network,
which provides a time delay to the voltage from the
auxiliary winding. Internally, this pin is connected to a
clamping network, a zero-crossing detector, an output
overvoltage (OP OVP) detector and a ringing
suppression time controller.
During on-state of the power switch a negative voltage
applies to the ZC pin. Through the internal clamping
network, the voltage at the pin is clamped to certain
level. However, it is highly recommended that a fast-
recovery diode D
voltage when the power switch is on. This is because
the device in MOS technology is sensitive to negative
voltage.
The voltage at the ZC pin v
threshold V
threshold at its falling edge, a pulse is generated which
is fed to the zero-crossing counter and the counter
value increases by 1.
After MOSFET is turned on, there will be some
oscillation on V
on ZC pin. To avoid the MOSFET is turned on
mistriggerred by such oscillation, a ringing suppression
timer is implemented. The time is dependent on the
voltage v
threshold V
shorter time is set when the voltage v
the threshold.
The voltage v
protection, as well. Once the voltage at this pin is
higher than the threshold V
main switch, the IC is latched off after a fixed blanking
time.
To achieve the switch-on at voltage valley, the voltage
from the auxiliary winding is fed to a time delay network
(the RC network consists of D
shown in typical application circuit) before it is applied
to the zero-crossing detector through the ZC pin. The
needed time delay to the main oscillation signal ∆t
should be approximately one fourth of the oscillation
period (by transformer primary inductor and drain-
source capacitor) minus the propagation delay from the
Quasi-Resonant PWM Controller
ZC
. When the voltage v
ZCT2
Zero-Crossing Counter and Ringing
Suppression Time Controller
ZCT1
ZC
DS
, a longer preset time applies, while a
. Once the voltage v
, which will also appear on the voltage
is used for the output overvoltage
zc
is added to block the negative
Functional Description
RM
.
OPOVP
ZC
zc
, R
is compared with the
during off-time of the
ZC
zc1
is lower than the
, R
ZC
October 2007
ZC
ICE2QS01
is higher than
zc2
crosses the
and C
zc
REG
as