iW1696

Low-Power Off-line Digital Green-Mode PWM Controller

iW1696

1.0 Features

● Primary-side feedback eliminates opto-isolators and

simplifies design

● 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

● Very tight constant voltage and constant current

regulation with primary-side-only feedback

● No external compensation components required

● Complies with EPA 2.0 energy-efficiency specifications

with ample margin

● Able to meet < 30 mW no load power consumption

● Low start-up current (10 μA typical)

● Built-in soft start

● Built-in short circuit protection and output overvoltage

protection

● Built-in current sense resistor short protection

● No audible noise over entire operation range

Figure 3.1: iW1696 Typical Application Circuit

2.0 Description

The iW1696 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 iW1696 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 overall

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.

The ultra-low start-up power and operating current at light

load ensure that the iW1696 is ideal for applications targeting

the newest regulatory standards for average efficiency.

3.0 Applications

● Low power AC/DC adapter/chargers for cell phones,

PDAs, digital still cameras

● Linear AC/DC replacement

L

+

GND

U1

iW1696

GND

OUTPUT

1

2

5

4

3

N

+