WS2259
Features
■ Burst Mode function
■ Low startup current (4uA)
■ Low operation current (1.7mA)
■ Built in Leading edge blanking (LEB)
■ Built in Synchronous slope compensation
■ Current mode operates
■ External programmable switching frequency
■ Cycle by cycle Over Current Protection
■ over temperature protection(OTP）
■ Soft-start
■ VDD over voltage protection and clamp
■ under voltage lockout with hysteresis(UVLO）
■ Driver Output clamped(13V)
■ Soft-driver function for lower EMI
■ Frequency jitter
■ Constant output power limited
■ Over load protection(OLP)
■ Free audio noise operation
General Description
WS2259 which is optimized for high performance is a
highly integrated current mode PWM control IC. It is applied
for switch power of the small-sized and medium-sized for
example the power adaptor. For lower the standby power and
higher RoHS compliant, the IC has the Burst Mode function
and very low startup current and working current. At the
condition of no load or light load, the IC operates in extended
‘burst mode’ to minimize switching loss by lower the switching
frequency. The low startup current and low operating current
contribute to a reliable power on startup design with WS2259.
A large value resistor could thus be used in the startup circuit
to minimize the power consumption and improve the efficiency
of the power convert.
The internal synchronous slope compensation circuit
improves system large signal stability and reduces the
possible subharmonic oscillation at high PWM duty cycle
output. Leading-edge blanking on current sense(SENSE)
input removes the signal glitch due to snubber circuit diode
reverse recovery and thus greatly reduces the external
component count and system cost in the design.
WS2259 offers complete protection coverage with
automatic self-recovery feature including cycle by cycle over
current protection (OCP), over load protection (OLP), over
temperature protection (OTP), VDD Over Voltage Protection,
under voltage lockout (UVLO). The gate-driven output is
clamped to maximum 13V to protect the external MOSFET.
Excellent EMI performance is achieved by using the frequency
jitter and the soft-switching at the totem pole gate drive output.
The tone energy at below 20KHZ is minimized in the design
and audio noise is eliminated during operation. The IC can be
used as the best alternative products of the linear power
supply or the RCC-mode power to improve the whole
performance of the switch power system and lower the cost.
WS2259 is offered in SOT23-6, SOP-8 and DIP-8 packages.
Applications
Universal switch power supply and offline AC/DC
flyback converter:
■ Battery Charger
■ Power Adaptor
■ Set-Top Box Power Supplies
■ Open-frame SMPS
Typical Application Circuit
Rev.A Apr.2011
WINSEMI [ SHENZHEN WINSEMI MICROELECTRONICS CO., LTD ]
