iW671
Digital Green-Mode Synchronous Rectifier Controller
1 Description
The iW671 is a high performance synchronous rectifier controller with an integrated MOSFET driver for flyback
converters operating at discontinuous conduction mode. Combined with the MOSFET, the iW671 can emulate the diode
rectifier at the secondary side of the flyback to reduce conduction loss. The iW671 determines the timing of the driver
by sensing the voltage across the RDS(ON) to achieve lossless sensing. The iW671 uses proprietary digital adaptive turn-
off control technology to minimize the turn-off deadtime of the synchronous rectifier so that the parallel Schottky diode
required by conventional synchronous rectifiers can be eliminated. The integrated driver has strong driving capability for
high efficiency. The operating power consumption of the controller excluding the driver is less than 4mW at no load to
achieve the ultra-low no-load power consumption for 5V applications. The iW671 integrates a pulse linear regulator to
maintain the operation of the synchronous rectifier at low system output voltage when the system is operating in constant
current (CC) mode.
The iW671 also integrates the adaptive voltage position monitor to detect the flyback converter output voltage
undershoot, enabling faster recovery from standby. Dialog’s iW1766C1 primary-side controllers are optimized to work
with the iW671 for very low output ripple, fast dynamic load response (DLR), and very low no-load power consumption
(< 15mW) at 230VAC input in a typical 5V, 2.5A power supply.
2 Features
● Digital adaptive turn-off control minimizes deadtime
and eliminates the parallel Schottky diode
● Intelligent low power management achieves ultra-low
no-load operating current < 0.65mA
● Integrated pulse linear regulator (PLR) allows SR
operation at low system output voltage down to 2V in
typical 5V, 2.5A USB charger applications
● Lossless MOSFET VDS sensing for SR timing control
● Integrated adaptive voltage position monitor for fast
flyback output voltage undershoot detection
● Wide input operating voltage up to 30V
● Optimized 5V MOSFET gate driver
● 8-pin SOIC and 8-pin MSOP packages
3 Applications
● Compact AC/DC adapters/chargers for media tablets
and smart phones
V
OUT
+
RTN
iW671
1
8
7
VPS
V
IN
2
DRV
V
CC
+
3
4
6
5
PLRIN
DRAIN
GND
OUT
Figure 3.1 : iW671 Typical Application Circuit
02-Feb-2022
Rev. 1.3
Product Summary
© 2022 Renesas Electronics
www.renesas.com
1 of 7