IW1691 Datasheet, PDF (1/24 Pages) Dialog Semiconductor – Digital PWM Current-Mode Controller for Quasi-Resonant Operation

iW1691
Digital PWM Current-Mode Controller for Quasi-Resonant Operation
1.0 Features
●● Primary-side feedback eliminates opto-isolators and
simplifies design
●● Quasi-resonant operation for highest overall efficiency
●● EZ-EMI ^® design to easily meet global EMI standards
●● Up to 130 kHz switching frequency enables small
adapter size
●● Built-in cable drop compensation
●● Very tight output voltage regulation
●● No external compensation components required
●● Complies with CEC/EPA no-load power consumption
and average efficiency regulations
●● Built-in output constant-current control with primary-side
feedback
●● Low start-up current (10 µA typical)
●● Built-in soft start
●● Built-in short circuit protection and output overvoltage
protection
●● Optional AC line under/overvoltage protection
●● PFM operation at light load
●● Current sense resistor short protection
●● Overtemperature Protection
2.0 Description
The iW1691 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 operates in quasi-resonant mode at heavy load 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 iW1691 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
current limit function enables optimized transformer design
in universal off-line applications over a wide input voltage
range.
The ultra-low operating current at light load ensures that
the iW1691 is ideal for applications targeting the newest
regulatory standards for average efficiency and standby
power.
3.0 Applications
●● AC/DC adapter/chargers for cell phones, PDAs, digital
still cameras
●● AC/DC adapters for consumer electronics
L
N
+
+
V_OUT
RTN
+
Optional
NTC
Thermistor
1 NC
V_CC 8
2 V_SENSE OUTPUT 7
3 V_IN
I_SENSE 6
4 SD
GND 5
U1
iW1691
Figure 3.1 : Typical Application Circuit
Rev. 2.0
iW1691
February 3, 2012

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