A LinkSwitch-HP device monolithically integrates a controller and high-voltage power MOSFET into one package. It has a newly developed analog control scheme, which enables continuous conduction mode (CCM), primary-side regulated (PSR) power supplies up to 90 W without the efficiency limitation of DCM or audible noise. It uses an enhanced peak current mode PWM control scheme with the multi-mode operation.
The multi-mode control engine uses the error amplifier output signal voltage at the COMPENSATION pin to set the operating peak current and switching frequency to maintain the output
voltage in regulation as shown in Figure 5. For COMPENSATION pin voltages lower than VC(MCM) (typ. 1.25 V) the device enters multi-cycle modulation (MCM) with a fixed peak current of 25% of the programmed current limit. Several innovative improvements have been added to the peak current mode control to allow primary side regulated CCM operation with no instability. The
device meets less than 30 mW input power with no-load at high-line (LNK67xx families).
- External current limit selection.
- Optional programmable shutdown delay time extension.• Optional remote On/Off.
- Optional fast AC reset.
- Primary-side sensed output overvoltage protection (OVP) .
- Lost regulation protection during output overload or short-circuit (auto-restart).
- Internal current limit over line compensation for constant overload power over the line.
- High-voltage bus overvoltage sense (line OV) for extended line surge withstand.
- High-voltage bus Undervoltage sense (line UV) for brown-in/ out protection.
- Accurate over-temperature protection (OTP).
- Output OVP/OCP/OTP shutdown type selection (hysteretic/
- Optional external latching shutdown input (current threshold)
- Cycle-by-cycle current limit control.
1 x LNK6667 High-Power Off-Line Switcher IC