NCP1235 Datasheet, PDF (1/34 Pages) ON Semiconductor – Fixed Frequency Current Mode Controller

NCP1235
Product Preview
Fixed Frequency Current
Mode Controller for Flyback
Converters
The NCP1235 is a new fixed−frequency current−mode controller
featuring Dynamic Self−Supply (DSS). This device is pin−to−pin
compatible with the previous NCP12xx families.
The DSS function greatly simplifies the design of the auxiliary
supply and the V_CC capacitor by activating the internal startup current
source to supply the controller during transients.
Due to frequency foldback, the controller exhibits excellent
efficiency in light load condition while still achieving very low
standby power consumption. Internal frequency jittering, ramp
compensation, and a versatile latch input make this controller an
excellent candidate for converters where components cost is the key
constraints.
In addition, the controller includes a new high voltage circuitry that
combines a start−up current source and a brown−out detector able to
sense the input voltage either from the rectified ac line or the dc
filtered bulk voltage. The high voltage sensing circuitry is used for the
overpower protection purposes as well. Overpower protection,
overload protection, and next protective features increases safety level
of the final application.
Finally, due to a careful design, the precision of critical parameters
is well controlled over the entire temperature range (−40°C to
+125°C).
www.onsemi.com
MARKING
DIAGRAM
SOIC−7
CASE 751U
8
35A065
ALYWX
G
1
35A065 = Specific Device Code
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W
= Work Week
G
= Pb−Free Package
PIN CONNECTIONS
Latch 1
FB 2
CS 3
GND 4
8 HV
6 V_CC
5 DRV
Features
(Top View)
• Fixed−Frequency Current−Mode Operation with Built−In Ramp
Compensation
• 65 kHz Oscillator Frequency
• Frequency Foldback then Skip Mode for Maximized Performance in
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 33 of this data sheet.
Light Load and Standby Conditions
• Timer−Based Overload Protection then Device is Latched
• High−voltage Current Source with Brown−Out
• Internal Thermal Shutdown
detection and Dynamic Self−Supply, Simplifying the
Design of the V_CC Capacitor
• Frequency Modulation for Softened EMI Signature,
including during Frequency Foldback mode
• Adjustable Overpower Compensation
• Latch−off Input for Severe Fault Conditions, Allowing
Direct Connection of an NTC for Overtemperature
Protection (OTP)
• V_CC Operation up to 28 V, with Overvoltage Detection
• $500 mA Peak Source / Sink Current Drive Capability
• Pin−to−Pin Compatible with the Existing NCP12xx
Series
• These Devices are Pb−Free, Halogen Free/BFR Free
and are RoHS Compliant
Typical Applications
• AC−DC Adapters for Notebooks, LCD, and Printers
• Offline Battery Chargers
• Consumer Electronic Power Supplies
• Auxiliary/Housekeeping Power Supplies
• 4.0 ms Soft−Start
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
© Semiconductor Components Industries, LLC, 2015
1
January, 2015 − Rev. P0
Publication Order Number:
NCP1235/D