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IW1697 Datasheet, PDF (1/12 Pages) Dialog Semiconductor – Low-Power Off-Line Digital Green-Mode PWM Controller | |||
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iW1697
Low-Power Off-Line Digital Green-Mode PWM Controller
1.0 Features
ââ Primary-side feedback eliminates opto-isolators and
simplifies design
ââ No-load power consumption < 20 mW at 230 Vac with
typical application circuit (5 star rating)
ââ Active start-up scheme enables fastest possible start-
up
ââ Fast dynamic load response
ââ Adaptive multi-mode PWM/PFM control improves
efficiency
ââ Quasi-resonant operation for highest overall efficiency
ââ EZ-EMI ® design to easily meet global EMI standards
ââ Direct drive of low-cost BJT switch
ââ Dynamic base current control
ââ Very tight constant voltage and constant current
regulation with primary-side-only feedback
ââ No external compensation components required
ââ Complies with EPA 2.0 energy-efficiency specifications
with ample margin
ââ Ultra-low start-up current (1.5 μA typical)
ââ Built-in soft start
ââ Built-in short circuit protection and output overvoltage
protection
ââ Built-in current sense resistor short circuit protection
ââ No audible noise over entire operating range
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2.0 Description
The iW1697 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 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 iW1697 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.
iWattâs innovative proprietary technology ensures that
power supplies built with iW1697 can achieve both highest
average efficiency and less than 20 mW no-load power
consumption, and have fast dynamic load response, all
with a typical application circuit. The active start-up scheme
enables shortest possible start-up time without sacrificing
no-load power loss.
3.0 Applications
ââ Low power AC/DC adapter/chargers for cell phones,
PDAs, digital still cameras
ââ Linear AC/DC replacement
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VOUT
GND
U1
iW1697
1 VCC
OUTPUT 6
2 VSENSE
GND 5
3 ASU
ISENSE 4
Rev. 1.1
Figure 3.1: iW1697 Typical Application Circuit
(Achieving < 20 mW No-load Power Consumption. Using Depletion Mode NFET as Active Start-up Device)
iW1697
February 1, 2012
Page 1
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