iW1677 Product Brief
Low-Power Off-Line Digital Green-Mode PWM Controller
1.0 Features
●
No-load power consumption < 20 mW at 230 V
ac
with
typical application circuit (5 star rating)
●
Fast dynamic load response for both one-time and
repetitive load transients
●
Very tight constant voltage and constant current
regulation over entire operating range
●
Primary-side feedback eliminates opto-isolators and
simplifies design
●
EZ-EMI
®
design enhances manufacturability
●
Intrinsically low common mode noise
●
Optimized 72 kHz maximum PWM switching frequency
achieves best size and efficiency
●
Active start-up scheme enables fastest possible start-up
●
Adaptive multi-mode PWM/PFM control improves
efficiency
●
Quasi-resonant operation for highest overall efficiency
●
Direct drive of low-cost BJT switch
●
Dynamic base current control
●
No external compensation components required
●
Complies with EPA 2.0 energy-efficiency specifications
with ample margin
●
Built-in soft start
●
Built-in short circuit protection and output overvoltage
protection
●
Built-in current sense resistor short circuit protection
●
No audible noise over entire operating range
L
V
OUT
GND
Intelligent AC-DC and LED Power™
2.0 Description
The iW1677 is a high performance AC/DC power supply
controller which uses digital control technology to build
peak current mode PWM
fl
yback power supplies. The
device together with an external active device (depletion
mode NFET or NPN BJT) provides a fast start-up without
compromising no-load power loss. The device directly
drives a power BJT and operates in quasi-resonant mode
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 iW1677 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 for both one-
time and repetitive load transients. The built-in power limit
function enables optimized transformer design in universal
off-line applications and allows for a wide input voltage
range.
iWatt’s innovative proprietary technology ensures that power
supplies built with the iW1677 can achieve both highest
average efficiency and less than 20 mW no-load power
consumption, and have fast dynamic load response in a
compact form factor. The active start-up scheme enables
shortest possible start-up time without sacrificing no-load
power loss.
3.0 Applications
●
Compact AC/DC adapter/chargers for cell phones,
PDAs, digital still cameras
●
Linear AC/DC replacement
+
N
+
U1
iW1677
1
2
3
V
CC
V
SENSE
ASU
OUTPUT
GND
I
SENSE
6
5
4
Figure 3.1: iW1677 Typical Application Circuit
(Achieving < 20 mW No-load Power Consumption. Using Depletion Mode NFET as the Active Start-up Device)
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iW1677 Product Brief
Low-Power Off-Line Digital Green-Mode PWM Controller
Intelligent AC-DC and LED Power™
L
+
+
N
V
OUT
GND
U1
iW1677
1
2
3
V
CC
V
SENSE
ASU
OUTPUT
GND
I
SENSE
6
5
4
Figure 3.2: iW1677 Typical Application Circuit
(Achieving < 20 mW No-load Power Consumption. Using NPN BJT as the Active Start-up Device)
4.0 Pinout Description
iW1677
1
2
3
V
CC
V
SENSE
ASU
OUTPUT
GND
I
SENSE
6
5
4
Figure 4.1: 6 Lead SOT-23 Package
Pin #
1
2
3
4
5
6
Name
V
CC
V
SENSE
ASU
I
SENSE
GND
OUTPUT
Type
Power Input
Pin Description
Power supply for control logic.
Analog Input Auxiliary voltage sense (used for primary regulation).
Output
Control signal for active start-up device (BJT or depletion NFET).
Analog Input Primary current sense. Used for cycle-by-cycle peak current control and limit.
Ground
Output
Ground.
Base drive for BJT.
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iW1677 Product Brief
Low-Power Off-Line Digital Green-Mode PWM Controller
5.0 Absolute Maximum Ratings
Absolute maximum ratings are the parameter values or ranges which can cause permanent damage if exceeded.
Intelligent AC-DC and LED Power™
Parameter
DC supply voltage range (pin 1, I
CC
= 20mA max)
Continuous DC supply current at V
CC
pin (V
CC
= 15 V
)
ASU output (pin 3)
Output (pin 6)
V
SENSE
input (pin 2, I
Vsense
≤
10 mA)
I
SENSE
input (pin 4)
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
Symbol
V
CC
I
CC
Value
-0.3 to 18
20
-0.3 to 18
-0.3 to 4.0
-0.7 to 4.0
-0.3 to 4.0
Units
V
mA
V
V
V
V
°C
°C
°C
°C/W
V
mA
T
J MAX
T
STG
T
LEAD
150
–65 to 150
260
190
2,000
±100
θ
JA
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iW1677 Product Brief
Low-Power Off-Line Digital Green-Mode PWM Controller
6.0 Physical Dimensions
6-Lead SOT Package
D
Symbol
Intelligent AC-DC and LED Power™
Millimeters
MIN
-
0.00
0.90
0.30
MAX
1.45
0.15
1.30
0.50
6
5
4
E1
1
2
3
E
A
A1
A2
B
C
e
e1
D
E
E1
e
L
C
e1
L
0.08
0.22
2.90 3.00
2.80 BSC
2.80 BSC
1.60 BSC
0.95 BSC
1.90 BSC
0.30
0°
0.60
8°
A1
A2
A
B
COPLANARITY
0.10
Compliant to JEDEC Standard MO-178AB
Controlling dimensions are in millimeters
SEATING
PLANE
Figure 6.1 : Physical dimensions, 6-lead SOT-23 package
This package is RoHS compliant and Halide free.
Soldering Temperature Resistance:
[a] Package is IPC/JEDEC Std 020D Moisture Sensitivity Level 1
[b] Package exceeds JEDEC Std No. 22-A111 for Solder Immersion Resistance;
packages can withstand 10 s immersion < 270ºC
Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions
or gate burrs shall not exceed 0.25 mm per side. D and E1 dimensions are determined at
datum H.
The package top may be smaller than the package bottom. Dimensions D and E1 are
are determined at the outermost extremes of the plastic body exclusive of mold flash, tie bar
burrs and interlead flash, but including any mismatch between top and bottom of the plastic
body. D and E1 dimensions are determined at datum H.
7.0 Ordering Information
Part Number
iW1677-00
iW1677-01
iW1677-03
iW1677-05
Options
Cable Comp = 0 mV
Cable Comp = 300 mV
Cable Comp = 450 mV
Cable Comp = 150 mV
Package
SOT-23
SOT-23
SOT-23
SOT-23
Description
Tape & Reel
1
Tape & Reel
1
Tape & Reel
1
Tape & Reel
1
Note 1: Tape & Reel packing quantity is 3,000 per reel. Minimum ordering quantity is 3,000.
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iW1677 Product Brief
Low-Power Off-Line Digital Green-Mode PWM Controller
About iWatt
iWatt Inc. is a fabless semiconductor company that develops intelligent power management ICs for computer, communication,
and consumer markets. The company’s patented
pulseTrain™
technology, the industry’s
fi
rst truly digital approach to power
system regulation, is revolutionizing power supply design.
Intelligent AC-DC and LED Power™
Trademark Information
© 2009 iWatt, Inc. All rights reserved. iWatt,
EZ-EMI
and
pulseTrain
are trademarks of iWatt, Inc. All other trademarks and
registered trademarks are the property of their respective companies.
Contact Information
Web:
http://www.iwatt.com
E-mail:
info@iwatt.com
Phone:
408-374-4200
Fax:
408-341-0455
iWatt Inc.
101 Albright Way
Los Gatos CA 95032-1827
Disclaimer
iWatt reserves the right to make changes to its products and to discontinue products without notice. The applications
information, schematic diagrams, and other reference information included herein is provided as a design aid only and are
therefore provided as-is. iWatt makes no warranties with respect to this information and disclaims any implied warranties of
merchantability or non-infringement of third-party intellectual property rights.
iWatt cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an iWatt product. No
circuit patent licenses are implied.
Certain applications using semiconductor products may involve potential risks of death, personal injury, or severe property
or environmental damage (“Critical Applications”).
IWATT SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED, OR WARRANTED TO
BE SUITABLE FOR USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS, OR OTHER CRITICAL
APPLICATIONS.
Inclusion of iWatt products in critical applications is understood to be fully at the risk of the customer. Questions concerning
potential risk applications should be directed to iWatt, Inc.
iWatt semiconductors are typically used in power supplies in which high voltages are present during operation. High-voltage
safety precautions should be observed in design and operation to minimize the chance of injury.
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