IW1677 Datasheet, PDF (1/16 Pages) Dialog Semiconductor – Low-Power Off-Line Digital Green-Mode PWM Controller

iW1677
Low-Power Off-Line Digital Green-Mode PWM Controller
1 Description
The iW1677 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 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.
Dialog’s innovative proprietary technology ensures that power supplies built with the iW1677 can achieve both highest
average efficiency and less than 20mW 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.
2 Features
●● No-load power consumption < 20mW 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
●● PrimAccurate^TM primary-side feedback eliminates
opto-isolators and simplifies design
●● Low EMI design enhances manufacturability
●● Intrinsically low common mode noise
●● Optimized 72kHz 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 loop 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
3 Applications
●● Compact low power AC/DC adapter/chargers for cell
phones, PDAs, digital still cameras
●● Linear AC/DC replacement
Datasheet
www.dialog-semiconductor.com
Rev. 2.0
1 of 16
3-June-2016
© 2016 Dialog Semiconductor