iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
1.0 Features
●
Primary-side feedback eliminates opto-isolators and
simplifies design
● Quasi-resonant operation for highest overall efficiency
●
EZ-EMI
®
design to easily meet global EMI standards
● Up to 130 kHz switching frequency enables small
adapter size
●
Built-in cable drop compensation
● Very tight output voltage regulation
● No external compensation components required
● Complies with CEC/EPA no-load power consumption
and average efficiency regulations
●
Built-in output constant-current control with primary-side
feedback
● Low start-up current (10 µA typical)
●
Built-in soft start
● Built-in short circuit protection and output overvoltage
protection
● Optional AC line under/overvoltage protection
● PFM operation at light load
●
Current sense resistor short protection
● Overtemperature Protection
2.0 Description
The iW1691 is a high performance AC/DC power supply
controller which uses digital control technology to build
peak current mode PWM flyback power supplies. The
device operates in quasi-resonant mode at heavy load to
provide high efficiency along with a number of key built-in
protection features while minimizing the external component
count, simplifying EMI design and lowering the total bill of
material cost. The iW1691 removes the need for secondary
feedback circuitry while achieving excellent line and load
regulation. It also eliminates the need for loop compensation
components while maintaining stability over all operating
conditions. Pulse-by-pulse waveform analysis allows for a
loop response that is much faster than traditional solutions,
resulting in improved dynamic load response. The built-in
current limit function enables optimized transformer design
in universal off-line applications over a wide input voltage
range.
The ultra-low operating current at light load ensures that
the iW1691 is ideal for applications targeting the newest
regulatory standards for average efficiency and standby
power.
3.0 Applications
● AC/DC adapter/chargers for cell phones, PDAs, digital
still cameras
● AC/DC adapters for consumer electronics
L
N
+
+
V
OUT
RTN
+
1
2
3
4
NC
V
SENSE
V
IN
SD
V
CC
8
OUTPUT
7
I
SENSE
6
GND
5
Optional
NTC
Thermistor
U1
iW1691
Figure 3.1 : Typical Application Circuit
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iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
4.0 Pinout Description
1
2
3
4
iW1691
NC
V
SENSE
V
IN
SD
V
CC
OUTPUT
I
SENSE
GND
8
7
6
5
Pin #
1
2
3
4
5
6
7
8
Name
NC
V
SENSE
V
IN
SD
GND
I
SENSE
OUTPUT
V
CC
Type
-
Pin Description
No connection.
Analog Input Auxiliary voltage sense (used for primary side regulation).
Analog Input Rectified AC line average voltage sense.
Analog Input
Ground
External shutdown control. Connect to ground through a resistor if not used.
(see section 10.16)
Ground.
Analog Input Primary current sense (used for cycle-by-cycle peak current control and limit).
Output
Power Input
Gate drive for external MOSFET switch.
Power supply for control logic and voltage sense for power-on reset circuitry.
5.0 Absolute Maximum Ratings
Absolute maximum ratings are the parameter values or ranges which can cause permanent damage if exceeded. For
maximum safe operating conditions, refer to Electrical Characteristics in Section 6.0.
Parameter
DC supply voltage range (pin 8, I
CC
= 20mA max)
DC supply current at V
CC
pin
Output (pin 7)
V
SENSE
input (pin 2, I
Vsense
≤ 10 mA)
V
IN
input (pin 3)
I
SENSE
input (pin 6)
SD input (pin 4)
Power dissipation at T
A
≤ 25°C
Maximum junction temperature
Storage temperature
Lead temperature during IR reflow for ≤ 15 seconds
Thermal Resistance Junction-to-Ambient
ESD rating per JEDEC JESD22-A114
Latch-Up test per JEDEC 78
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Symbol
V
CC
I
CC
Value
-0.3 to 18
20
-0.3 to 18
-0.7 to 4.0
-0.3 to 18
-0.3 to 4.0
-0.3 to 18
Units
V
mA
V
V
V
V
V
mW
°C
°C
°C
°C/W
V
mA
P
age
2
P
D
T
J MAX
T
STG
T
LEAD
526
125
–65 to 150
260
160
2,000
±100
θ
JA
iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
6.0 Electrical Characteristics
V
CC
= 12 V, -40°C ≤ T
A
≤ 85°C, unless otherwise specified (Note 1)
Parameter
V
IN
SECTION (Pin 3)
Start-up low voltage threshold
Start-up current
Shutdown low voltage threshold
Input
impedance
V
SENSE
SECTION (Pin 2)
Input leakage current
Nominal voltage threshold
Output OVP threshold
- 00, -01, -03 , -11 (Note 2)
OUTPUT OVP threshold -09 (Note 2)
Output OVP threshold -04, -08
(Note 2)
Output OVP threshold -10 (Note 2)
OUTPUT SECTION (Pin 7)
Output low level ON-resistance
Output high level ON-resistance
Rise time (Note 2)
Fall time (Note 2)
Maximum switching frequency
-00, -01, -03, -04, -08, -09,-10, -11
(Note 3)
Symbol
V
INSTLOW
I
INST
V
UVDC
Z
IN
Test Conditions
T
A
= 25°C, positive edge
V
IN
= 10 V, C
VCC
= 10 µF
T
A
= 25°C, negative edge
After start-up
Min
335
Typ
369
10
Max
406
15
243
Unit
mV
µA
mV
kW
201
221
25
I
BVS
V
SENSE(NOM)
V
SENSE(MAX)
V
SENSE(MAX)
V
SENSE(MAX)
V
SENSE(MAX)
V
SENSE
= 2 V
T
A
=25°C, negative edge
T
A
=25°C, negative edge
T
A
=25°C, negative edge
T
A
=25°C, negative edge,
Load = 100%
T
A
=25°C, negative edge,
Load = 100%
1.523
1.754
1.797
1.836
1.871
1.538
1.846
1.892
1.933
1.969
1
1.553
1.938
1.987
2.030
2.067
μA
V
V
V
V
V
R
DS(ON)LO
R
DS(ON)HP
t
R
t
F
f
SW(MAX)
I
SINK
= 5 mA
I
SOURCE
= 5 mA
T
A
= 25°C, C
L
= 330 pF
10% to 90%
T
A
= 25°C, C
L
= 330 pF
90% to 10%
Any combination of
line and load
40
175
200
40
300
60
W
W
ns
ns
130
140
kHz
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iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
6.0 Electrical Characteristics (cont.)
V
CC
= 12 V, -40°C ≤ T
A
≤ 85°C, unless otherwise specified (Note 1)
Parameter
V
CC
SECTION (Pin 8)
Maximum operating voltage (Note 2)
Start-up threshold
Undervoltage lockout threshold
Operating current
I
SENSE
SECTION (Pin 6)
Peak limit threshold
Isense short protection reference
CC regulation threshold limit (Note 2)
SD SECTION (Pin 4)
Shutdown threshold
Shutdown threshold in Startup
(Note 2)
Input leakage current
Pull down resistance
Symbol
V
CC(MAX)
V
CC(ST)
V
CC(UVL)
I
CCQ
Test Conditions
Min
Typ
Max
16
Unit
V
V
V
mA
V
CC
rising
V
CC
falling
C
L
= 330 pF,
V
SENSE
= 1.5 V
10.8
5.5
12
6.0
3.5
13.2
6.6
5
V
PEAK
V
RSNS
V
REG-TH
1.045
0.127
1.1
0.15
1.0
1.155
0.173
V
V
V
V
SD-TH
V
SD-TH(ST)
I
BVSD
R
SD
T
A
= 25°C
0.95
1.0
1.2
1.05
V
V
V
SD
= 1.0 V
T
A
= 25°C
7916
8333
1
8750
µA
W
Notes:
Note 1. Adjust VCC above the start-up threshold before setting at 12 V.
Note 2. Guaranteed by design and characterization. Minimum output OVP threshold is specified for 100% load; for loads
less than 100% the minimum output OVP threshold will be less.
Note 3. Operating frequency varies based on the line and load conditions, see Theory of Operation for more details.
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iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
7.0 Typical Performance Characteristics
V
CC
Supply Start-up Current (µA)
V
CC
Start-up Threshold (V)
2.0
4.0
8.0
6.0
V
CC
(V)
10.0
12.0
14.0
9.0
12.2
6.0
12.0
3.0
11.8
0.0
0.0
11.6
-50
-25
Ambient Temperature (°C)
0
25
50
75
100
125
Figure 7.1 : V
CC
vs. V
CC
Supply Start-up Current
% Deviation of Switching Frequency from Ideal
Figure 7.2 : Start-Up Threshold vs. Temperature
0.3 %
Internal Reference Voltage (V)
-25
0
25
50
75
100
125
2.01
-0.3 %
2.00
-0.9 %
1.99
-1.5 %
-50
Ambient Temperature (°C)
1.98
-50
Figure 7.3 : % Deviation of Switching Frequency to
Ideal Switching Frequency vs. Temperature
Ambient Temperature (°C)
Figure 7.4 : Internal Reference vs. Temperature
-25
0
25
50
75
100
125
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