INFINEON ICE2QS03

Datasheet,Version 2.0, December 4, 2009
ICE2QS03
Quasi-Resonant
Controller
PWM
Power Management & Supply
N e v e r
s t o p
t h i n k i n g .
ICE2QS03
Revision History:
December 4, 2009
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Edition December 4, 2009
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 12/4/09.
All Rights Reserved.
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characteristics (“Beschaffenheitsgarantie”). With respect to any examples or hints given herein, any typical values
stated herein and/or any information regarding the application of the device, Infineon Technologies hereby
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ICE2QS03
Quasi-Resonant PWM Controller
Product Highlight
• Active burst mode for low standby power
• Digital frequency reduction for better overall system efficiency
• Integrated power cell for IC self-power supply
Features
Description
•
•
ICE2QS03 is a quasi-resonant PWM controller
optimized for off-line switch power supply applications
such as LCD TV, CRT TV and notebook adapter. The
digital frequency reduction with decreasing load
enables a quasi-resonant operation till very low load.
As a result, the overall system efficiency is significantly
improved compared to other conventional solutions.
The active burst mode operation enables an ultra-low
power consumption at standby mode with small and
controllable output voltage ripple. Based on the
BiCMOS technology, the product has a wide operation
range (up to 26V) of IC power supply and lower power
consumption. The numerous protection functions give
a full protection of the power supply system in failure
situations. All of these make the ICE2QS03 an
outstanding controller for quasi-resonant flyback
converter in the market.
•
•
•
•
•
•
•
•
•
Quasiresonant operation till very low load
Active burst mode operation at light/no load for low
standby input power (< 100mW)
Digital frequency reduction with decreasing load
Power cell for VCC pre-charging with constant
current
Built-in digital soft-start
Foldback correction and cycle-by-cycle peak
current limitation
Auto restart mode for VCC Overvoltage protection
Auto restart mode for VCC Undervoltage protection
Auto restart mode for openloop/overload protection
Latch-off mode for adjustable output overvoltage
protection
Latch-off mode for Short-winding protection
Typical Application Circuit
Wp
Snubber
Cbus
85 ~ 265Vac
RVCC
Lf
DO
DVCC
CVCC
VO
Cf
Ws
CO
RZC2
RZC1
Wa
Dr1~Dr4
CZC
HV
VCC
ZC
CPS
Power
Cell
GND
Control Unit
Q1
Rb1
Zero Crossing Detection
Active Burst Mode
FB
Gate
Driver
GATE
Optocoupler
Current
Limitation
Protection Block
ICE2QS03
Version 2.0
Rovs1
Rc1
CS
RCS
Current Mode Control
Type
ICE2QS03
Rb2
Power Management
Digital Process Block
CFB
CDS
TL431
Cc1
Cc2
Rovs2
Package
PG-DIP-8-6
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December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Table of Contents
Page
1
1.1
1.2
1.3
Pin Configuration and Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Pin Configuration with PG-DIP-8-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Package PG-DIP-8-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Pin Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2
Representative Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3
3.1
3.2
3.3
3.3.1
3.3.1.1
3.3.1.2
3.3.2
3.3.3
3.4
3.4.1
3.5
3.5.1
3.5.2
3.5.3
3.6
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
VCC Pre-Charging and Typical VCC Voltage During Start-up . . . . . . . . . . .7
Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Digital Frequency Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Up/down counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Zero crossing (ZC counter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Ringing suppression time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Switch Off Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Current Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Foldback Point Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Active Burst Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Entering Active Burst Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . .10
During Active Burst Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Leaving Active Burst Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Protection Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.3.6
4.3.7
4.3.8
4.3.9
4.3.10
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Supply Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Internal Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
PWM Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Current Sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Soft Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Foldback Point Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Digital Zero Crossing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Active Burst Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Gate Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5
Outline Dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Version 2.0
4
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Pin Configuration and Functionality
1
Pin Configuration and
Functionality
1.1
1.3
ZC (Zero Crossing)
At this pin, the voltage from the auxiliary winding after
a time delay circuit is applied. Internally, this pin is
connected to the zero-crossing detector for switch-on
determination. Additionally, the output overvoltage
detection is realized by comparing the voltage Vzc with
an internal preset threshold.
Pin Configuration with PG-DIP8-6
Pin
Symbol
Function
1
ZC
Zero Crossing
2
FB
Feedback
3
CS
Current Sense
4
HV
High Voltage Input
5
HV
High Voltage Input
6
GATE
Gate Drive Output
7
VCC
Controller Supply Voltage
8
GND
Controller Ground
1.2
FB (Feedback)
Normally, an external capacitor is connected to this pin
for a smooth voltage VFB. Internally, this pin is
connected to the PWM signal generator for switch-off
determination (together with the current sensing
signal), the digital signal processing for the frequency
reduction with decreasing load during normal
operation, and the Active Burst Mode controller for
entering Active Burst Mode operation determination
and burst ratio control during Active Burst Mode
operation. Additionally, the open-loop / over-load
protection is implemented by monitoring the voltage at
this pin.
CS (Current Sense)
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, shortwinding protection is realised by monitoring the voltage
Vcs during on-time of the main power switch.
Package PG-DIP-8-6
ZC
1
8
GND
FB
2
7
VCC
CS
3
6
GATE
HV
4
5
HV
Figure 1
Pin Functionality
GATE (Gate Drive Output)
This output signal drives the external main power
switch, which is a power MOSFET in most case.
HV (High Voltage)
The pin HV is connected to the bus voltage, externally,
and to the power cell, internally. The current through
this pin pre-charges the VCC capacitor with constant
current once the supply bus voltage is applied.
VCC (Power supply)
VCC pin is the positive supply of the IC. The operating
range is between VVCCoff and VVCCOVP.
Pin Configuration PG-DIP-8-6(top view)
GND (Ground)
This is the common ground of the controller.
Version 2.0
5
December 4, 2009
Figure 2
Version 2.0
6
2pF
25kO
RFB
VREF
D1
C3
C2
VFBBOff
VFBBOn
VFBEB
VFBZL
VFBZH
VFBR1
VFBOLP
VZCRS
VZCOVP
C10
C9
C8
C7
C6
C5
C4
Count=7
C1
Comparator
ZC counter
tBEB
&
Active
Burst Mode
Ringing
Suppression
G1
Active Burst Block
Regulation
tOLP_B
Delay
tZCOVP
tCOUNT
Up/down counter
clk
Zero Crossing
VVCCOVP
VPWM
q
OSC
f
en sB
PWM
Comparator
Soft-start
18V
Current Mode
10.5
Undervoltage Lockout
Power Management
GPWM
1
G3
1
G4
R
S
G8
C15
Q
G2
1
G7
1
S
Q
C14
Leading
Edge
Blanking
tLEB
TOnMax
1pF
VCSSW
10kO
Current Limiting
D2
Gate
Drive
Depl. CoolMOS®
Gate Drive
R
latched
Protect
&
G9
Protection
R
Autorestart
Protect
S Q
TOffMax
Delay
tCSSW
OTP
Foldback
Correction
C13 VCSB
10us
Internal
Bias
PWM Control
PWM OP
&
G6
&
G5
C12
Voltage
Reference
Startup Cell
HV
CS
GND
GATE
2
FB
ZC
VZCC
VCC
Quasi-Resonant PWM Controller
ICE2QS03
Representative Block diagram
Representative Block diagram
Representative Block diagram
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Functional Description
3
Functional Description
then will reach a constant value depending on output
load.
3.1
VCC Pre-Charging and Typical
VCC Voltage During Start-up
3.2
At the time ton, the IC begins to operate with a soft-start.
By this soft-start the switching stresses for the switch,
diode and transformer are minimised. The soft-start
implemented in ICE2QS03 is a digital time-based
function. The preset soft-start time is 12ms with 4
steps. If not limited by other functions, the peak voltage
on CS pin will increase step by step from 0.32V to 1V
finally.
In ICE2QS03, a high voltage startup cell is integrated.®.
As shown in Figure 2, the start cell consists of a high
voltage device and a controller, whereby the high
voltage device is controlled by the controller. The
startup cell provides a pre-charging of the VCC
capacitor till VCC voltage reaches the VCC turned-on
threshold VVCCon and the IC begins to operate.
Once the mains input voltage is applied, a rectified
voltage shows across the capacitor Cbus. The high
voltage device provides a current to charge the VCC
capacitor Cvcc. Before the VCC voltage reaches a
certain value, the amplitude of the current through the
high voltage device is only determined by its channel
resistance and can be as high as several mA. After the
VCC voltage is high enough, the controller controls the
high voltage device so that a constant current around
1mA is provided to charge the VCC capacitor further,
until the VCC voltage exceeds the turned-on threshold
VVCCon. As shown as the time phase I in Figure 3, the
VCC voltage increase near linearly and the charging
speed is independent of the mains voltage level.
Vcs_sst
(V)
1.00
0.83
0.66
0.49
0.32
ton
Figure 4
VVCC
VVCCon
i
ii
3.3
iii
Figure 3
t2
t
VCC voltage at start up
The time taking for the VCC pre-charging can then be
approximately calculated as:
t
V
⋅C
VCCon vcc
= -----------------------------------------1
I VCCch arg e2
[1]
where IVCCcharge2 is the charging current from the
startup cell which is 1.05mA, typically.
Exceeds the VCC voltage the turned-on threshold
VVCCon of at time t1, the startup cell is switched off, and
the IC begins to operate with a soft-start. Due to power
consumption of the IC and the fact that still no energy
from the auxiliary winding to charge the VCC capacitor
before the output voltage is built up, the VCC voltage
drops (Phase II). Once the output voltage is high
enough, the VCC capacitor receives then energy from
the auxiliary winding from the time point t2 on. The VCC
Version 2.0
3
6
9
12
Time(ms)
Maximum current sense voltage during
softstart
Normal Operation
The PWM controller during normal operation consists
of a digital signal processing circuit including an up/
down counter, a zero-crossing counter (ZC counter)
and a comparator, and an analog circuit including a
current measurement unit and a comparator. The
switch-on and -off time points are each determined by
the digital circuit and the analog circuit, respectively. As
input information for the switch-on determination, the
zero-crossing input signal and the value of the up/down
counter are needed, while the feedback signal VFB and
the current sensing signal VCS are necessary for the
switch-off determination. Details about the full
operation of the PWM controller in normal operation
are illustrated in the following paragraphs.
VVCCoff
t1
Soft-start
3.3.1
Digital Frequency Reduction
As mentioned above, the digital signal processing
circuit consists of an up/down counter, a ZC counter
and a comparator. These three parts are key to
implement digital frequency reduction with decreasing
load. In addition, a ringing suppression time controller
is implemented to avoid mistriggering by the high
frequency oscillation, when the output voltage is very
low under conditions such as soft start or output short
circuit . Functionality of these parts is described as in
the following.
7
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Functional Description
threshold voltages, VFBZL and VFBZH, are changed
internally depending on the line voltage levels.
3.3.1.1
Up/down counter
The up/down counter stores the number of the zero
crossing to be ignored before the main power switch is
switched on after demagnetisation of the transformer.
This value is fixed according to the feedback voltage,
VFB, which contains information about the output
power. Indeed, in a typical peak current mode control,
a high output power results in a high feedback voltage,
and a low output power leads to a low regulation
voltage. Hence, according to VFB, the value in the up/
down counter is changed to vary the power MOSFET
off-time according to the output power. In the following,
the variation of the up/down counter value according to
the feedback voltage is explained.
The feedback voltage VFB is internally compared with
three threshold voltages VRL, VRH and VRM, at each
clock period of 48ms. The up/down counter counts then
upward, keep unchanged or count downward, as
shown in Table 1.
up/down counter
action
Always lower than VFBZL
Count upwards till
7
Once higher than VFBZL, but
always lower than VFBZH
Stop counting, no
value changing
Once higher than VFBZH, but
always lower than VFBR1
Count downwards
till 1
Once higher than VFBR1
VFBR1
VFBZH
VFBZL
n+2
n+2
n+2
n+2
n+1
n
n-1
t
n+1
Up/down
counter
Case 1
4
5
6
6
6
6
5
4
3 1
Case 2
2
3
4
4
4
4
3
2
1 1
Case 3
7
7
7
7
7
7
6
5
4 1
Figure 5
1
Up/down counter operation
3.3.1.2
Zero crossing (ZC counter)
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 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.
The ZC counter has a minimum value of 0 and
maximum value of 7. After the internal MOSFET is
turned off, every time when the falling voltage ramp of
on ZC pin crosses the 100mV threshold, a zero
crossing is detected and ZC counter will increase by 1.
It is reset every time after the GATE output is changed
to high.
The voltage vZC is also used for the output overvoltage
protection. Once the voltage at this pin is higher than
the threshold VZCOVP during off-time of the 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 Dzc, Rzc1, Rzc2 and Czc as
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 drainsource capacitor) minus the propagation delay from
Set up/down
counter to 1
In the ICE2QS03, the number of zero crossing is
limited to 7. Therefore, the counter varies between 1
and 7, and any attempt beyond this range is ignored.
When VFB exceeds VFBR1 voltage, the up/down counter
is initialised to 1, in order to allow the system to react
rapidly to a sudden load increase. The up/down
counter value is also intialised to 1 at the start-up, to
ensure an efficient maximum load start up. Figure 5
shows some examples on how up/down counter is
changed according to the feedback voltage over time.
The use of two different thresholds VFBZL and VFBZH to
count upward or downward is to prevent frequency
jittereing when the feedback voltage is close to the
threshold point. However, for a stable operation, these
two thresholds must not be affected by the foldback
current limitation (see Section 3.4.1), which limits the
VCS voltage. Hence, to prevent such situation, the
Version 2.0
t
VFB
Operation of the up/down counter
vFB
T=48ms
n
Table 1
clock
8
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Functional Description
thedetected zero-crossing to the switch-on of the main
switch tdelay, theoretically:
T osc
∆t = ------------ – t
delay
4
To avoid mistriggering caused by the voltage spike
across the shunt resistor at the turn on of the main
power switch, a leading edge blanking time, tLEB, is
applied to the output of the comparator. In other words,
once the gate drive is turned on, the minimum on time
of the gate drive is the leading edge blanking time.
In addition, there is a maximum on time, tOnMax,
limitation implemented in the IC. Once the gate drive
has been in high state longer than the maximum on
time, it will be turned off to prevent the switching
frequency from going too low because of long on time.
[2]
This time delay should be matched by adjusting the
time constant of the RC network which is calculated as:
τ
td
= C
R zc1 ⋅ R zc2
⋅ --------------------------------zc R
+R
zc1
zc2
[3]
3.4
3.3.2
Ringing suppression time
After MOSFET is turned off, there will be some
oscillation on VDS, which will also appear on the voltage
on ZC pin. To avoid that the MOSFET is turned on
mistriggerred by such oscillations, a ringing
suppression timer is implemented. The timer is
dependent on the voltage vZC. When the voltage vZC is
lower than the threshold VZCRS, a longer preset time
applies, while a shorter time is set when the voltage vZC
is higher than the threshold.
There is a cycle by cycle current limitation realized by
the current limit comparator to provide an overcurrent
detection. The source current of the MOSFET is
sensed via a sense resistor RCS. By means of RCS the
source current is transformed to a sense voltage VCS
which is fed into the pin CS. If the voltage VCS exceeds
an internal voltage limit, adjusted according to the
Mains voltage, the comparator immediately turns off
the gate drive.
To prevent the Current Limitation process from
distortions caused by leading edge spikes, a Leading
Edge Blanking time (tLEB) is integrated in the current
sensing path.
A further comparator is implemented to detect
dangerous current levels (VCSSW) which could occur if
one or more transformer windings are shorted or if the
secondary diode is shorted. To avoid an accidental
latch off, a spike blanking time of tCSSW is integrated in
the output path of the comparator .
3.3.2.1
Switch on determination
After the gate drive goes to low, it can not be changed
to high during ring suppression time.
After ring suppression time, the gate drive can be
turned on when the ZC counter value is higher or equal
to up/down counter value.
However, it is also possible that the oscillation between
primary inductor and drain-source capacitor damps
very fast and IC can not detect enough zero crossings
and ZC counter value will not be high enough to turn on
the gate drive. In this case, a maximum off time is
implemented. After gate drive has been remained off
for the period of TOffMax, the gate drive will be turned on
again regardless of the counter values and VZC. This
function can effectively prevent the switching
frequency from going lower than 20kHz, otherwise
which will cause audible noise, during start up.
3.4.1
Foldback Point Correction
When the main bus voltage increases, the switch on
time becomes shorter and therefore the operating
frequency is also increased. As a result, for a constant
primary current limit, the maximum possible output
power is increased, which the converter may have not
been designed to support.
To avoid such a situation, the internal foldback point
correction circuit varies the VCS voltage limit according
to the bus voltage. This means the VCS will be
decreased when the bus voltage increases. To keep a
constant maximum input power of the converter, the
3.3.3
Switch Off Determination
In the converter system, the primary current is sensed
by an external shunt resistor, which is connected
between low-side terminal of the main power switch
and the common ground. The sensed voltage across
the shunt resistor vCS is applied to an internal current
measurement unit, and its output voltage V1 is
compared with the regulation voltage VFB. Once the
voltage V1 exceeds the voltage VFB, the output flip-flop
is reset. As a result, the main power switch is switched
off. The relationship between the V1 and the vCS is
described by:
V
1
= 3.3 ⋅ V
Version 2.0
CS
+ 0.7
Current Limitation
[4]
9
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Functional Description
about Active Burst Mode operation are explained in the
following paragraphs.
required maximum VCS versus various input bus
voltage can be calculated, which is shown in Figure 6.
3.5.1
Entering Active Burst Mode Operation
For determination of entering Active Burst Mode
operation, three conditions apply:
• the feedback voltage is lower than the threshold of
VFBEB(1.25V). Accordingly, the peak current sense
voltage across the shunt resistor is 0.17;
• the up/down counter is 7; and
• a certain blanking time (tBEB).
Once all of these conditions are fulfilled, the Active
Burst Mode flip-flop is set and the controller enters
Active Burst Mode operation. This multi-condition
determination for entering Active Burst Mode operation
prevents mistriggering of entering Active Burst Mode
operation, so that the controller enters Active Burst
Mode operation only when the output power is really
low during the preset blanking time.
1
Vcs-max(V)
0.9
0.8
0.7
0.6
80
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400
Vin(V)
Figure 6
Variation of the VCS limit voltage according
to the IZC current
According to the typical application circuit, when
MOSFET is turned on, a negative voltage proportional
to bus voltage will be coupled to auxiliary winding.
Inside ICE2QS03, an internal circuit will clamp the
voltage on ZC pin to nearly 0V. As a result, the current
flowing out from ZC pin can be calculated as
I
V BUS N a
= -----------------------ZC
R
N
ZC1 P
3.5.2
During Active Burst Mode Operation
After entering the Active Burst Mode the feedback
voltage rises as VOUT starts to decrease due to the
inactive PWM section. One comparator observes the
feedback signal if the voltage level VBH (3.6V) is
exceeded. In that case the internal circuit is again
activated by the internal bias to start with swtiching.
Turn-on of the power MOSFET is triggered by the
timer. The PWM generator for Active Burst Mode
operation composes of a timer with a fixed frequency of
52kHz, typically, and an analog comparator. Turn-off is
resulted by comparison of the voltage signal v1 with an
internal threshold, by which the voltage across the
shunt resistor VcsB is 0.34V, accordingly. A turn-off can
also be triggered by the maximal duty ratio controller
which sets the maximal duty ratio to 50%. In operation,
the output flip-flop will be reset by one of these signals
which come first.
If the output load is still low, the feedback signal
decreases as the PWM section is operating. When
feedback signal reaches the low threshold VBL(3.0V),
the internal bias is reset again and the PWM section is
disabled until next time regultaion siganl increases
beyond the VBH threshold. If working in Active Burst
Mode the feedback signal is changing like a saw tooth
between 3.0V and 3.6V shown in Figure 7.
[5]
When this current is higher than IZC_1, the amount of
current exceeding this threshold is used to generate an
offset to decrease the maximum limit on VCS. Since the
ideal curve shown in Figure 6 is a nonlinear one, a
digital block in ICE2QS03 is implemented to get a
better control of maximum output power. Additional
advantage to use digital circuit is the production
tolerance is smaller compared to analog solutions. The
typical maximum limit on VCS versus the ZC current is
shown in Figure 7.
1
Vcs-max(V)
0.9
0.8
0.7
3.5.3
Leaving Active Burst Mode Operation
The feedback voltage immediately increases if there is
a high load jump. This is observed by one comparator.
As the current limit is 34% during Active Burst Mode a
certain load is needed so that feedback voltage can
exceed VLB (4.5V). After leaving active busrt mode,
maximum current can now be provided to stabilize VO.
In addition, the up/down counter will be set to 1
0.6
300
500
700
900
1100
1300
1500
1700
1900
2100
Iz c(uA)
Figure 7
3.5
VCS-max versus IZC
Active Burst Mode Operation
At light load condition, the IC enters Active Burst Mode
operation to minimize the power consumption. Details
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Quasi-Resonant PWM Controller
ICE2QS03
Functional Description
IC is reset and the main power switch is then kept off.
After the VCC voltage falls below the threshold VVCCoff,
the startup cell is activated. The VCC capacitor is then
charged up. Once the voltage exceeds the threshold
VVCCon, the IC begins to operate with a new soft-start.
In case of open control loop or output over load, the
feedback voltage will be pulled up . After a blanking
time of 24ms, the IC enters auto-restart mode. The
blanking time here enables the converter to provide a
high power in case the increase in VFB is due to a
sudden load increase. During off-time of the power
switch, the voltage at the zero-crossing pin is
monitored for output over-voltage detection. If the
voltage is higher than the preset threshold vZCOVP, the
IC is latched off after the preset blanking time.
If the junction temperature of IC exceeds 140 °C, the IC
enter into autorestart mode.
If the voltage at the current sensing pin is higher than
the preset threshold vCSSW during on-time of the power
switch, the IC is latched off. This is short-winding
protection.
During latch-off protection mode, when the VCC
voltage drops to 10.5V,the startup cell is activated and
the VCC voltage is charged to 18V then the startup cell
is shut down again and repeats the previous procedure.
There is also an maximum on time limitation inside
ICE2QS03. Once the gate voltage is high longer than
tOnMAx, it is turned off immediately.
immediately after leaving Active Burst Mode. This is
helpful to decrease the output voltage undershoot.
VFB
Leaving
Active Burst
Mode
Entering
Active Burst
Mode
VFBLB
VFBBOn
VFBBOff
VFBEB
Blanking Window (tBEB)
VCS
1.0V
t
Current limit level
during Active Burst
Mode
VCSB
VVCC
t
VVCCoff
VO
t
Max. Ripple < 1%
t
Figure 8
3.6
Signals in Active Burst Mode
Protection Functions
The IC provides full protection functions. The following
table summarizes these protection functions.
Table 2
Protection features
VCC Overvoltage
Auto Restart Mode
VCC Undervoltage
Auto Restart Mode
Overload/Open Loop
Auto Restart Mode
Over temperature
Auto Restart Mode
Output Overvoltage
Latched Off Mode
Short Winding
Latched Off Mode
During operation, the VCC voltage is continuously
monitored. In case of an under- or an over-voltage, the
Version 2.0
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Quasi-Resonant PWM Controller
ICE2QS03
Electrical Characteristics
4
Electrical Characteristics
Note:
All voltages are measured with respect to ground (Pin 8). The voltage levels are valid if other ratings are
not violated.
4.1
Note:
Absolute Maximum Ratings
Absolute maximum ratings are defined as ratings, which when being exceeded may lead to destruction
of the integrated circuit. For the same reason make sure, that any capacitor that will be connected to pin 7
(VCC) is discharged before assembling the application circuit.
Parameter
Symbol
Limit Values
min.
max.
Unit
Remarks
HV Voltage
VHV
-
500
V
VCC Supply Voltage
VVCC
-0.3
27
V
FB Voltage
VFB
-0.3
5.0
V
ZC Voltage
VZC
-0.3
5.0
V
CS Voltage
VCS
-0.3
5.0
V
GATE Voltage
VOUT
-0.3
27
V
Maximum current out from ZC pin
IZCMAX
3
-
mA
Junction Temperature
Tj
-40
125
°C
Storage Temperature
TS
-55
150
°C
Thermal Resistance
Junction -Ambient
RthJA
-
90
K/W
PG-DIP-8
ESD Capability (incl. Drain Pin)
VESD
-
2
kV
Human body model1)
1)
According to EIA/JESD22-A114-B (discharging a 100pF capacitor through a 1.5kΩ series resistor)
4.2
Note:
Operating Range
Within the operating range the IC operates as described in the functional description.
Parameter
Symbol
Limit Values
min.
max.
Unit
VCC Supply Voltage
VVCC
VVCCoff
VVCCOVP V
Junction Temperature of
Controller
TjCon
-25
125
Version 2.0
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Remarks
°C
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Electrical Characteristics
4.3
4.3.1
Note:
Characteristics
Supply Section
The electrical characteristics involve the spread of values within the specified supply voltage and junction
temperature range TJ from – 25 °C to 125 °C. Typical values represent the median values, which are
related to 25°C. If not otherwise stated, a supply voltage of VCC = 18 V is assumed.
Parameter
Symbol
Limit Values
min.
typ.
max.
Unit
Test Condition
Start Up Current
IVCCstart
-
300
550
µA
VVCC =VVCCon -0.2V
VCC Charge Current
IVCCcharge1
-
5.0
-
mA
VVCC = 0V
IVCCcharge2
0.8
-
-
mA
VVCC = 1V
IVCCcharge3
-
1.0
-
mA
VVCC =VVCCon -0.2V
Maximum Input Current of
Startup Cell and CoolMOS®
IDrainIn
-
-
2
mA
VVCC =VVCCon -0.2V
Leakage Current of
Startup Cell and CoolMOS®
IDrainLeak
-
0.2
50
µA
VDrain = 610V
at Tj=100°C
Supply Current in normal
operation
IVCCNM
-
1.5
2.3
mA
output low
Supply Current in
Auto Restart Mode with Inactive
Gate
IVCCAR
-
300
-
µA
IFB = 0A
Supply Current in Latch-off Mode
IVCClatch
-
300
-
µA
Supply Current in Burst Mode with
inactive Gate
IVCCburst
-
500
950
µA
VCC Turn-On Threshold
VVCCon
17.0
18.0
19.0
V
VCC Turn-Off Threshold
VVCCoff
9.8
10.5
11.2
V
VCC Turn-On/Off Hysteresis
VVCChys
-
7.5
-
V
4.3.2
VFB = 2.5V, exclude the
current flowing out from
FB pin
Internal Voltage Reference
Parameter
Internal Reference Voltage
Version 2.0
Symbol
VREF
Limit Values
min.
typ.
max.
4.80
5.00
5.20
13
Unit
Test Condition
V
Measured at pin FB
IFB=0
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Electrical Characteristics
4.3.3
PWM Section
Parameter
Symbol
Limit Values
min.
typ.
max.
Unit
Feedback Pull-Up Resistor
RFB
14
23
33
kΩ
PWM-OP Gain
GPWM
3.18
3.3
-
-
Offset for Voltage Ramp
VPWM
0.63
0.7
-
V
Maximum on time in normal
operation
tOnMax
22
30
41
µs
4.3.4
Current Sense
Parameter
Symbol
Limit Values
min.
typ.
max.
Unit
Peak current limitation in normal
operation
VCSth
0.97
1.03
1.09
V
Leading Edge Blanking time
tLEB
200
330
460
ns
Peak Current Limitation in
Active Burst Mode
VCSB
0.29
0.34
0.39
V
4.3.5
Test Condition
Soft Start
Parameter
Symbol
Limit Values
min.
typ.
max.
Unit
Soft-Start time
tSS
8.5
12
-
ms
soft-start time step
tSS_S1)
-
3
-
ms
Internal regulation voltage at
first step
VSS11)
-
1.76
-
V
Internal regulation voltage step
at soft start
VSS_S1)
-
0.56
-
V
1)
Test Condition
Test Condition
The parameter is not subjected to production test - verified by design/characterization
4.3.6
Foldback Point Correction
Parameter
Symbol
Limit Values
min.
typ.
max.
Unit
ZC current first step threshold
IZC_FS
0.35
0.5
0.621
mA
ZC current last step threshold
IZC_LS
1.8
2
2.2
mA
CS threshold minimum
VCSMF
-
0.66
-
V
Version 2.0
14
Test Condition
Izc=2.2mA, VFB=3.8V
December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Electrical Characteristics
4.3.7
Digital Zero Crossing
Parameter
Symbol
Limit Values
Unit
Test Condition
min.
typ.
max.
Zero crossing threshold voltage VZCCT
50
100
170
mV
Ringing suppression threshold
VZCRS
-
0.7
-
V
Minimum ringing suppression
time
tZCRS1
1.8
2.5
3.4
µs
VZC > VZCRS
Maximum ringing suppression
time
tZCRS2
-
25
-
µs
VZC < VZCRS
Threshold to set Up/Down
Counter to one
VFBR1
3.9
V
Threshold for downward
counting at low line
VFBZHL
3.2
V
Threshold for upward counting
at low line
VFBZLL
2.5
V
Threshold for downward
counting at hig line
VFBZHH
2.9
V
Threshold for upward counting
at highline
VFBZLH
2.3
V
ZC current for IC switch
threshold to high line
IZCSH
-
1.3
-
mA
ZC current for IC switch
threshold to low line
IZCSL
-
0.8
-
mA
Counter time1)
tCOUNT
Maximum restart time in normal
operation
tOffMax
1)
48
30
42
ms
57.5
µs
The parameter is not subjected to production test - verified by design/characterization
Version 2.0
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Quasi-Resonant PWM Controller
ICE2QS03
Electrical Characteristics
4.3.8
Active Burst Mode
Parameter
Symbol
Limit Values
Unit
min.
typ.
max.
-
1.25
-
V
Feedback voltage for entering
Active Burst Mode
VFBEB
Minimum Up/down value for
entering Active Burst Mode
NZC_ABM
Blanking time for entering Active
Burst Mode
tBEB
-
24
-
ms
Feedback voltage for leaving
Active Burst Mode
VFBLB
-
4.5
-
V
Feedback voltage for burst-on
VFBBOn
-
3.6
-
V
Feedback voltage for burst-off
VFBBOff
Fixed Switching Frequency in
Active Burst Mode
fsB
-
52
-
Max. Duty Cycle in Active Burst
Mode
DmaxB
-
0.5
-
4.3.9
7
3.0
V
kHz
Protection
Parameter
Symbol
Limit Values
min.
typ.
max.
24.0
25.0
26.0
Unit
VCC overvoltage threshold
VVCCOVP
Over Load or Open Loop
Detection threshold for OLP
protection at FB pin
VFBOLP
Over Load or Open Loop
Protection Blanking Time
tOLP_B
20
30
44
ms
Output Overvoltage detection
threshold at the ZC pin
VZCOVP
3.55
3.7
3.84
V
Blanking time for Output
Overvoltage protection
tZCOVP
Threshold for short winding
protection
VCSSW
1.63
1.68
1.78
V
Blanking time for short-windding
protection
tCSSW
-
190
-
ns
Over temperature protection1)
TjCon
-
140
-
0
Note:
Test Condition
4.5
Test Condition
V
V
µs
100
C
The trend of all the voltage levels in the Control Unit is the same regarding the deviation except VVCCOVP
Version 2.0
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ICE2QS03
Electrical Characteristics
4.3.10
Gate Drive
Parameter
Symbol
Limit Values
min.
Output voltage at logic low
VGATElow
Output voltage at logic high
VGATEhigh
9.0
Unit
Test Condition
V
VVCC=18V
IOUT = 20mA
V
VVCC=18V
IOUT = -20mA
1.0
V
V
VVCC = 7V
IOUT = 20mA
typ.
max.
-
1.0
10.0
Output voltage active shut down VGATEasd
Rise Time
trise
-
117
-
ns
COUT = 1.0nF
VGATE= 2V ... 8V
Fall Time
tfall
-
27
-
ns
COUT = 1.0nF
VGATE= 8V ... 2V
Version 2.0
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December 4, 2009
Quasi-Resonant PWM Controller
ICE2QS03
Outline Dimension
5
Outline Dimension
PG-DIP-8-6 / PG-DIP-8-9
(Leadfree Plastic Dual In-Line Outline)
Figure 9
PG-DSO-8 (Pb-free lead plating Plastic Dual Small Outline)
Dimensions in mm
Version 2.0
18
December 4, 2009
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