The HT7L5600 is a single-stage, isolated, primary-side offline LED lighting controller that achieves a high power factor. Power control is implemented by controlling an external MOSFET and accurate LED constant current regulation from the primary-side information. This can significantly simplify the LED lighting system design by eliminating the secondary-side feedback components and the normally required opto-coupler. The extremely low start-up current and quiescent current reduces the total power consumption to provide a high efficiency solution for lighting applications. The HT7L5600 provides several protection functions, which include VCC Under Voltage Lockout (UVLO), Over Current Protection (OCP), Output LED String Open Protection, Output LED String Short Protection, VCC Over Voltage Protection (OVP) and Leading-Edge Blanking (LEB) for current sensing. Additionally and to ensure system reliability, the device includes a fully integrated thermal protection function. To protect the external power MOSFET from being damaged by an over voltage, the device DRV pin voltage is clamped to about 16V.
The high level of functional integration minimises the external component count giving major advantages in terms of cost and circuit board area. The device is supplied in a SOT23-6 package.
Small outline SOT23-6 package
Primary-side current sensing and regulation without an opto-coupler
Wide AC input range — from 85VAC to 265VAC
High Power Factor of >0.9 without additional circuitry
Accurate constant current (< ±3%)
Low start-up current which reduces power dissipation
Full protection functions for enhanced safety:
– Gate driver output voltage clamp
– VCC over voltage protection — VCC OVP
– VCC under-voltage lockout with hysteresis — VCC UVLO
– Output LED string over current protection
– Output LED string short / open protection
– On-chip over temperature protection — OTP