Product Overview

Product Overview
NCP1207B: PWM Controller, Free Running Quasi-Resonant Current Mode
For complete documentation, see the data sheet
Product Description
The NCP1207A/B combines a true current mode modulator and a demagnetization detector to ensure full borderline/critical
Conduction Mode in any load/line conditions and minimum drain voltage switching (Quasi-Resonant operation). Due to its inherent
skip cycle capability, the controller enters burst mode as soon as the power demand falls below a predetermined level. As this
happens at low peak current, no audible noise can be heard. For the NCP1207A, an internal 8.0 micro s timer prevents the free-run
frequency to exceed 125 kHz (therefore below the 150 kHz CISPR-22 EMI starting limit), while the skip adjustment capability lets the
user select the frequency at which the burst foldback takes place. For the NCP1207B, the internal timer duration is reduced to 4.5
micro s to allow operation at higher frequencies (up to 200 kHz).
The Dynamic Self-Supply (DSS) drastically simplifies the transformer design in avoiding the use of an auxiliary winding to supply the
NCP1207A/B. This feature is particularly useful in applications where the output voltage varies during operation (e.g. battery
chargers). Due to its high-voltage technology, the IC is directly connected to the high-voltage DC rail. As a result, the short-circuit trip
point is not dependent upon any VCC auxiliary level.
The transformer core reset detection is done through an auxiliary winding which, brought via a dedicated pin, also enables fast
overvoltage Protection (OVP). Once an OVP has been detected, the IC permanently latches off.
Finally, the continuous feedback signal monitoring implemented with an overcurrent fault protection circuitry (OCP) makes the final
design rugged and reliable.
Features
•
•
•
•
•
•
•
Free-Running Borderline/Critical Mode Quasi-Resonant Operation
Current-Mode with Adjustable Skip-Cycle capability
Auto-Recovery Over Current Protection
500 mA Peak Current Source/Sink Capability
Internal 1.0 ms SoftStart
Internal 4.5 s Minimum TOFF
Latched Over Voltage Protection
Applications
End Products
• Auxiliary power supplies
• AC/DC adapters for notebook
• Offline battery chargers
Part Electrical Specifications
Product
Compliance
Status
Topolog
y
Control
Mode
fsw Typ
(kHz)
StandUVLO
by Mode (V)
Short
Circuit
Protecti
on
Latch
Soft
Start
VCC Max Drive
(V)
Cap.
(mA)
Packag
e Type
NCP1207BDR2G
Pb-free
Active
Flyback
Current
Mode
Up to
1000
Yes
Yes
Yes
Yes
18
SOIC-7
Halide free
Yes
500 /
500
Application Diagram
For more information please contact your local sales support at www.onsemi.com
Created on: 6/30/2016