WS2596B Datasheet, PDF (6/9 Pages) List of Unclassifed Manufacturers – High Efficiency Charger Control IC

WS2596B Product Description
Constant Current Operation
WS2596B detects the falling edge of the FB input voltage on
each cycle. If a 0.1V falling edge of FB is not detected, the
WS2596B will stop switching.
Secondary current waveform
In CC operation, the CC loop control function of WS2596B
will keep a fixed proportion between D1 on-time Tons and
D1 off-time Toffs by discharging or charging the capacitance.
The fixed proportion is：
Tons _ 1
Toffs 1
The relationship between the output constant-current Iout
and secondary peak current Ipks is given by:
Iout  ¹  Ipks  ^Tons
2
Tons  Toffs
At the instant of D1 turn-on, the primary current transfers to
the secondary at an amplitude of:
Ipks  ^Np  Ipk
Ns
Thus the output constant-current is given by:
Iout  ¹  ^Np  Ipk  ^Tons  ¹  ^Np  Ipk
2 Ns
Tons  Toffs 4 Ns
Cable Compensation
WS2596B detects the duty cycle (Tons/T) of the secondary
side using internal RC filter. The larger the Tons/T， which
means the greater the load, the IC drags more current from
FB pin, thus through the feedback loop, the output voltage
would be higher.
Leading Edge Blanking
When the power switch is turned on, a turn-on spike will
occur on the sense-resistor. To avoid false-termination of the
switching pulse, a 800ns leading-edge blanking is built in.
During this blanking period, the current sense comparator is
disabled and the gate driver can not be switched off.
CCM Protection
The WS2596B is designed to operate in discontinuous
conduction mode (DCM) in both CV and CC modes. To avoid
operating in continuous conduction mode (CCM), the
VCC Over Voltage Protection and Clamp
When the VCC voltage reaches 17.9V, WS2596B will start a
5mA clamp current inside, make the VCC voltage is not up,
avoid error VCC_OVP when VCC is changed by load
changing which caused by large leakage inductance and other
factors. When the output voltage is too high, the auxiliary
winding current is greater than 5mA, resulting in VCC 18.7V,
the chip will stop the output pulse, enter the auto-restart mode
until the error is removed. Reasonable set of VCC voltage,
VCC_OVP can be used to accurately set the output
over-voltage protection.
Output Over Voltage Protection
When VFB>6V (continues for 6 cycles) since the Vout is too
high, or VCC>18.7V, WS2596B will enter Over Voltage
Protection status. The switching pulses will be stopped, and
IC auto-restart.
Output Under Voltage Protection
When Vout is less than 60% of the value of designing, and
remains more than 64mS, WS2596B will enter Under Voltage
Protection status. The switching pulses will be stopped, and
IC auto-restart.
Intelligent Thermal Control and OTP
When Tj rises to 133℃, internal intelligent thermal control will
make the output power reduced.
When Tj is 150℃, IC will enter OTP, then begin to auto-restart.
Pin Open / Short Protection
WS2596B has built-in pin open/short protections, such as
GND open protection, CS open/short protection, Rcs
open/short protection, FB resister open/short protection. Each
kind of bugs like above happened, IC will stop operating in
order to avoid any damage to the system and load.
Secondary SBD Short and Transformer Saturation
Protection
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WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
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