Document
NCP4302
Secondary Side
Synchronous Flyback
Controller
The NCP4302 is a full featured controller and driver that provide all the control and protection functions necessary for implementing a synchronous rectifier operation in a flyback converter. With the use of the NCP4302, the space conscious flyback applications such as Adaptors, chargers, set top boxes can achieve significant efficiency improvements at minimal extra cost. In addition to the synchronous rectifier control, the IC incorporates an accurate TL431 type shunt regulator, current monitoring circuit and optocoupler driver to provide a single IC secondary solution. The NCP4302 works with any type of flyback topology (continuous mode, Quasi−resonant mode or discontinuous mode) – providing a high level of versatility.
Features
• Self−contained Control of Synchronous Rectifier in CCM, DCM, and
QR Flyback Applications
• Interface to External Signal for CCM Mode • True Secondary Zero Current Detection • High Gate Drive Currents (2.5 A Source/Sink) • High Voltage Operation • Current Sense Flexibility (MOSFET RDS(on) OR CS Resistor) • Accurate Low Voltage Reference
− NCP4302A 2.55 V, 1% − NCP4302B 1.275 V, 1%
• Programmable Independent Secondary Side ton and toff Delays • Maximum Frequency of Operation up to 250 kHz • These are Pb−Free Devices
Typical Applications
• Notebook Adapters • LCD TV Adapters • Consumer Appliances such as DVD, VCR • Power Over Ethernet Applications (IP phones, Wireless Access
Points)
• Battery Chargers
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8
1
x A L Y W G
SO−8 D SUFFIX CASE 751
MARKING DIAGRAM
8
4302x ALYW
G 1
= Reference Voltage (A or B) = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package
PIN CONFIGURATION
SYNC/CS 1 TRIG 2 CATH 3 VREF 4
8 VCC 7 DRV 6 GND 5 DLYADJ
(Top View)
ORDERING INFORMATION
Device
Package
Shipping†
NCP4302ADR2G SO−8 2500/Tape & Reel (Pb−Free)
NCP4302BDR2G SO−8 2500/Tape & Reel (Pb−Free)
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D.
© Semiconductor Components Industries, LLC, 2015
May, 2015 − Rev. 4
1
Publication Order Number: NCP4302/D
NCP4302
PIN DESCRIPTION
Pin Number
Symbol
1 SYNC/CS
2 TRIG
3 CATH 4 VREF 5 DLYADJ
6 GND 7 DRV 8 VCC
Description Connected to the flyback winding. The current on this pin is sensed and used to turn on the Synchronous Rectification MOSFET (SRFET). This pin is also used to sense the zero crossing of the MOSFET current either using the RDS(on) of the SRFET or using an external current sense resistor connected between drain of the SRFET and the flyback winding. Input pin for direct turn−off of the MOSFET. Typically connected to a signal from primary controller (for CCM mode) or a signal derived from the transformer (for QR mode). Has very short propagation delay to output (<50 ns). Feedback compensation pin for the TL431 shunt regulator. Has the capability to sinking 10 ma of opto current. Output voltage feedback through resistive divider connected to this pin. Regulated at 1.28 V (option B) or 2.55 V (option A). A resistive divider between the power supply output and ground with the center point tied to the DLYADJ input pin allows for independent adjustment of the minimum ton and toff delay time. The maximum external capacitance from this pin to ground is 25 pF. Return pin for the controller – connected to the output return. Drive output for external MOSFET – 2.5 A peak drive capability, internally clamped to 13.5 V (Maximum) Bias voltage for the controller. Maximum voltage is 28 V.
MAXIMUM RATINGS
Rating
Symbol
Value
Unit
Power Supply Input Current
VCC −0.3 to 28
V
ICC 100 mA
Drive Voltage Current
VDRV
−0.3 to 18 100
V mA
Drive Current Source Sink
IDRV
2.5 −2.5
Apk
Analog and Logic Inputs Maximum Voltage Current
TRIG, VREF, DLYADJ
SYNC/CS
−0.3 to 10 100
− 10 to 95 100
V mA V mA
Operating Junction Temperature Range
TJ −40 to 125 °C
Maximum Junction Temperature
TJmax
150
°C
Storage Temperature Range
TSmax
−65 to 150
°C
Lead Temperature (Soldering, 10 s)
TLmax
300
°C
Reference input Current, continuous
IREF
−0.05 to 10
mA
Total Power Dissipation
PD 225 mW
Thermal Resistance Junction−to−Ambient
qJA 178 °C/W
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality should not be assumed, damage may occur and reliability may be affected. 1. This device series contains ESD protection and exceeds the following tests:
Pin 1−8: Human Body Model 2000 V per JEDEC Standard JESD22, Method A114E. Machine Model (MM) 200 V per JEDEC Standard JESD22, Method A115A. 2. This device contains Latch−up protection and exceeds ±100 ma per JEDEC Standard JESD78
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NCP4302
VCC DRV GND
CS in
VCC Mngt. UVLO ON 10.4 V UVLO OFF.