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PDF IW1706 Data sheet ( Hoja de datos )
| Número de pieza | IW1706 | |
| Descripción | Low-Power Off-Line Digital Green-Mode PWM Controller | |
| Fabricantes | iWatt | |
| Logotipo |  |
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iW1706
Low-Power Off-Line Digital Green-Mode PWM Controller
1.0 Features
2.0 Description
●● Primary-side feedback eliminates opto-isolators and
simplifies design
●● Adaptively controlled soft start-up enables fast and
smooth start-up for a wide range of capacitive loads
(from 330 μF to 6000 μF)
●● Very tight constant voltage regulation
●● EZ-EMI ® design enhances manufacturability
●● Intrinsically low common mode noise
●● Optimized 72 kHz maximum PWM switching frequency
achieves best size and efficiency
●● 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 short circuit protection and output overvoltage
protection
The iW1706 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
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 iW1706 features a distinctive
soft-start scheme, which allows for fast and yet smooth
start-up with both small and large capacitive loads. The
iW1706 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
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 iW1706 can achieve both
highest average efficiency and fast yet smooth start-up with
a wide range of capacitive loads, and are ideal for network
power adapter applications.
●● Built-in current sense resistor short circuit protection
●● Constant current control enables output current limit and
overload protection
●● No audible noise over entire operating range
3.0 Applications
●● Network power adapters for ADSL, wireless access
points, routers.
L
+
N
+ VOUT
GND
U1
iW1706
1 VCC
OUTPUT 5
2 GND
3 VSENSE
ISENSE 4
Figure 3.1: iW1706 Typical Application Circuit
Rev. 1.1
iW1706
February 1, 2012
Page 1
1 page  
iW1706
Low-Power Off-Line Digital Green-Mode PWM Controller
8.0 Functional Block Diagram
ENABLE
Start-up
VSENSE 3
Signal
VFB
Conditioning
Digital
Logic
Control
GND 2
VSENSE(NOM)
= 1.533 V
DAC
OCP
IPK
VIPK
1 VCC
BJT
Base
Drive
5 Output
1.15 V
4 ISENSE
Figure 8.1: iW1706 Functional Block Diagram
9.0 Theory of Operation
The iW1706 is a digital controller which uses a new,
proprietary primary-side control technology to eliminate the
opto-isolated feedback and secondary regulation circuits
required in traditional designs. This results in a low-cost
solution for low power AC/DC adapters. The core PWM
processor uses fixed-frequency Discontinuous Conduction
Mode (DCM) operation at higher power levels and switches
to variable frequency operation at light loads to maximize
efficiency. Furthermore, iWatt’s digital control technology
enables fast dynamic response, tight output regulation, and
full featured circuit protection with primary-side control.
Referring to the block diagram in Figure 8.1, the digital
logic control block generates the switching on-time and
off-time information based on the output voltage and
current feedback signal and provides commands to
dynamically control the external BJT base current. The
system loop is automatically compensated internally by a
digital error amplifier. Adequate system phase margin and
gain margin are guaranteed by design and no external
analog components are required for loop compensation.
The iW1706 uses an advanced digital control algorithm to
reduce system design time and increase reliability.
Furthermore, accurate secondary constant-current operation
is achieved without the need for any secondary-side sense
and control circuits.
The iW1706 uses adaptive multi-mode PWM/PFM control
to dynamically change the BJT switching frequency for
efficiency, EMI, and power consumption optimization. In
addition, it achieves unique BJT quasi-resonant switching to
further improve efficiency and reduce EMI. Built-in single-
point fault protection features include overvoltage protection
(OVP), output short circuit protection (SCP), over current
protection (OCP), and ISENSE fault detection. In particular,
it ensures that power supplies built with the iW1706 are
best suited for power adapter applications such as ADSL
modems that have large capacitive loads.
iWatt’s digital control scheme is specifically designed to
address the challenges and trade-offs of power conversion
design. This innovative technology is ideal for balancing
new regulatory requirements for green mode operation
with more practical design considerations such as lowest
possible cost, smallest size and high performance output
control.
Rev. 1.1
iW1706
February 1, 2012
Page 5
5 Page 
iW1706
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 first truly digital approach to
power system regulation, is revolutionizing power supply design.
Trademark Information
© 2012 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: https://www.iwatt.com
E-mail: [email protected]
Phone: 408-374-4200
Fax: 408-341-0455
iWatt Inc.
675 Campbell Technology Parkway, Suite 150
Campbell, CA 95008
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.
Rev. 1.1
iW1706
February 1, 2012
Page 11
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet IW1706.PDF ] | |
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