NCP1238: Fixed Frequency Current Mode PWM Controller

The NCP1238 is a new generation of the NCP12xx fixed-frequency current-mode controllers featuring Dynamic Self-Supply (DSS), pin to pin compatible with the previous generation. The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal start-up current source to supply the controller during transients. Due to its proprietary Soft-Skip™ mode combined with frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. This Soft-Skip feature also dramatically reduces the risk of acoustic noise, which enables the use of inexpensive transformers and capacitors in the clamping network. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where ruggedness and components cost are the key constraints. In addition, the controller includes a new high voltage circuitry that combines a startup current source and a brown-out / line OVP detector able to sense the input voltage either from the rectified ac line or the dc filtered bulk voltage. Finally, due to a careful design, the precision of critical parameters is well controlled over the entire temperature range (-40°C to +125°C), enabling easier design and increased safety (e.g. ±5% for the peak current limit, ±7% for the oscillator).

技术特性

Timer−Based Overload Protections with Auto− Recovery (Option B) or Latched (Option A) Operation
High−Voltage Current Source with DSS with Built−in Brown−out and Line Overvoltage Protections
Fixed−Frequency Current−Mode Operation with Built−in Ramp Compensation
Frequency Jittering for a Reduced EMI Signature
Adjustable Overpower Compensation
Latch−off Input for Severe Fault Conditions, with Direct Connection of an NTC for Overtemperature Protection (OTP)
Protection Against Winding Short−Circuit
Frequency Foldback transitioning into Soft−Skip for Improved Performance in Standby
65 kHz Oscillator (100 kHz and 133 kHz Versions Available Upon Request)

优势

Overload protection independent of the auxiliary winding
Reduced EMI signature
Improved Performance in Standby

应用

Ac-dc Adapters for Notebooks, LCD, and Printers
Offline Battery Chargers
Consumer Electronic Power Supplies
Auxiliary/Housekeeping Power Supplies

封装图 PACKAGE DIMENSIONS

订购信息 Ordering Information

产品

状况

Compliance

具体说明

封装

MSL*

容器

预算价格 (1千个数量的单价）

类型

外形

类型

数量

NCP1238AD65R2G

Active

Pb-free

Halide free

Fixed Frequency Current Mode PWM Controller

SOIC-8

751U

Tape and Reel

2500

$0.6667

NCP1238BD65R2G