|
|
PDF IW1678 Data sheet ( Hoja de datos )
| Número de pieza | IW1678 | |
| Descripción | Low-Power Off-line Digital Green-Mode PWM Controller | |
| Fabricantes | iWatt | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de IW1678 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
|
No Preview Available !
iW1678
Low-Power Off-line Digital Green-Mode PWM Controller
1.0 Features
2.0 Description
●● Primary-side feedback eliminates opto-isolators and
simplifies design
●● 64-kHz PWM switching frequency
●● No-load power consumption < 100 mW at 230 Vac with
tight dynamic load transient response
●● Able to meet < 30 mW no-load power consumption with
large value pre-load resistor
●● Adaptive multi-mode PWM/PFM control improves
efficiency
●● Quasi-resonant operation for highest overall efficiency
●● EZ-EMI ® design to easily meet global EMI standards
●● Direct drive of low-cost BJT switch
●● Dynamic base current control
●● Very tight constant voltage and constant current
regulation with primary-side-only feedback
The iW1678 is a high performance AC/DC power supply
controller which uses digital control technology to build peak
current mode PWM flyback power supplies. The iW1678’s
64-kHz PWM switching frequency allows the design of ultra-
compact AC/DC adapters and chargers. 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 iW1678 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.
●● No external compensation components required
●● Complies with EPA 2.0 energy-efficiency specifications
with ample margin
●● Low start-up current (8 μA typical)
●● Built-in soft start
iWatt’s innovative proprietary technology ensures that power
supplies built with iW1678 can achieve both highest average
efficiency and less than 100 mW no-load power consumption
in a compact form factor.
3.0 Applications
●● Built-in short circuit protection and output overvoltage ●● Low power compact AC/DC adapter/chargers for cell
protection
phones, PDAs, digital still cameras
●● Built-in current sense resistor short circuit protection
●● Linear AC/DC replacement
●● No audible noise over entire operating range
L
+
N
+ VOUT
GND
Rev. 1.1
U1
iW1678
1 VCC
OUTPUT 5
2 GND
3 VSENSE
ISENSE 4
Figure 3.1: iW1678 Typical Application Circuit
iW1678
3/12/12
Page 1
1 page  
iW1678
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)
= 1.538 V
DAC
OCP
IPK
VIPK
1 VCC
BJT
Base
Drive
5 Output
1.1 V
4 ISENSE
Figure 8.1: iW1678 Functional Block Diagram
9.0 Theory of Operation
The iW1678 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 iW1678 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 iW1678 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 protection
features include overvoltage protection (OVP), output short
circuit protection (SCP), over current protection (OCP),
single point fault protection and ISENSE fault detection.
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
iW1678
3/12/12
Page 5
5 Page 
iW1678
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
© 2008 iWatt, Inc. All rights reserved. iWatt, the iW light bulb, 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.
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
iW1678
3/12/12
Page 11
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet IW1678.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| IW1677 | Low-Power Off-Line Digital Green-Mode PWM Controller |  Dialog Semiconductor |
| IW1678 | Low-Power Off-line Digital Green-Mode PWM Controller | iWatt |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |