HT7L4815 Non-isolation Buck LED Lighting Driver with Active PFC Features General Description • Non-isolation buck topology The HT7L4815 is a non-isolation buck PWM controller for LED lighting applications. The device has a fully integrated PFC circuit which operates in a boundary conduction mode (BCM) to achieve high power factor values. A high voltage power MOSFETs is integrated in the device. With full control provided over the internal MOSFETs, the device can easily meet the exacting LED current and high power factor requirements. • Integrated 500V MOSFET • 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 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 protection ♦♦ Output LED string open protection ♦♦ On-chip over temperature protection – OTP The device 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. 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 8-pin SOP package. • Package: 8-pin SOP Applications • General illumination • E26/27, T5/T8 LED Lamps • Other LED Lighting Applications Block Diagram Reference & Bias UVLO VCC 3 Starter VCC OVP OTP OCP 5,6 DRAIN OTP OTP ZCD OVP ZCD 4 Logic Control ZCD Comparator Min Off Time OCP PWM Generator COMP 2 Driver LEB OCP 7,8 CS EA 0.2V 1 VSS Rev. 1.00 1 June 26, 2015 HT7L4815 Pin Assignment VSS 1 8 CS COMP 2 7 CS VCC 3 6 DRAIN ZCD 4 5 DRAIN HT7L4815 8 SOP-A Pin Description Pin No. Symbol 1 VSS 2 COMP 3 VCC Power supply pin. Zero-current detect pin. 4 ZCD 5, 6 DRAIN 7, 8 CS Description Ground pin. Loop compensation pin. A capacitor is placed between COMP and GND. Internal high voltage power MOSFET drain terminals. Current sense pin. A resistor is connected to sense the MOSFET current. Absolute Maximum Ratings Parameter Range Internal MOSFET drain source voltage -0.3V to 500V VCC supply voltage -0.3V to 33V CS pin Input voltage -0.3V to 6V COMP pin Output voltage -0.3V to 6V ZCD pin Maximum current 3mA (source), 3mA (sink) Maximum operating junction temperature 150°C Storage temperature range -55°C to 150°C Recommended Operating Ranges Parameter Range VCC Supply voltage 17V~25V Operating junction temperature -40°C~125°C 18.3W@300mA, 90~264Vac 21W@300mA, 180~264Vac Output power Rev. 1.00 2 June 26, 2015 HT7L4815 Electrical Characteristics Symbol Parameter VCC=18V, Ta=25°C Test Condition Min Typ Max Unit V Power Supply (VCC Pin) VCCON UVLOON — — 18 — VCCOFF UVLOOFF — — 10 — V VCCHYS UVLO Hysteresis — 7 — — V — VOVP VCC OVP Trip Point ISTART Start-up Current Before turn-on, @ VCC=UVLOON - 1V IQ Quiescent Current No switching 26 29 32 V — 10 20 μA — 0.6 1 mA 194 200 206 mV Error Amplifier VFB Feedback Reference Voltage Ta=25°C Current Sense Comparator TLEB Leading Edge Blanking Time — — 400 — ns VCL Current Limit Threshold — — 1.1 — V Over Current Trip Point — — 0.9 — V Over Current Release Point — — 0.2 — V — 3 — V — -0.2 — V — 1.5 — V VOCP Zero Current Detector VZCDH Upper Clamp Voltage IZCD=300μA VZCDL Lower Clamp Voltage IZCD=-2.5mA VZCDA Positive-Going Edge — VZCDT Negative-Going Edge — — 1 — V IOVP OVP Current on ZCD pin — 270 300 330 μA TB_OVP Blanking Time for OVP Detection — — 1 — μs TSTART Start Timer Period — — 40 — μs TOFF Minimum Off Time — — 4 — μs — — 150 — °C — 2.5 — Ω 500 — — V Starter Over Temperature Protection OTP Over Temperature Trip Point Power MOSFET RDS Power MOSFET Switch ON Resistance @ VGS=10V, IDS=0.5A BVDSS Power MOSFET Drain-Source Voltage Rev. 1.00 @ VGS=0V, IDS<250μA 3 June 26, 2015 HT7L4815 16 201 14 200.5 12 VFB (mV) start up current (uA) Typical Performance Characteristics 10 8 6 200 199.5 199 198.5 4 198 -40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 100 120 temperature (℃) temperature (℃) Figure 5. VFB vs. temperature Figure 1. Start-Up current vs. temperature operating current (mA) 2 1.95 1.9 1.85 1.8 1.75 1.7 1.65 1.6 -40 -20 0 20 40 60 temperature (℃) 80 100 120 Figure 2. Operation current vs. temperature Figure 6. Temperature vs. Wide AC Voltage 19 UVLO_on(V) 18.6 18.2 17.8 17.4 17 -40 -20 0 20 40 60 80 100 120 temperature (℃) Figure 7. Efficiency vs. Wide AC Voltage Figure 3. UVLO_on vs. temperature 11 UVLO_off(V) 10.6 10.2 9.8 9.4 9 -40 -20 0 20 40 60 temperature (℃) 80 100 120 Figure 8. Temperature vs. High AC Voltage Figure 4. UVLO_off vs. temperature Rev. 1.00 4 June 26, 2015 HT7L4815 Figure 9. Efficiency vs. High AC Voltage Typical Application Circuit HT7L4815 90Vac~265Vac 5 DRAIN ZCD 4 6 DRAIN CS 8 3 VCC CS 7 2 COMP LED+ VSS 1 LED- Functional Description Boundary Conduction Mode – BCM The HT7L4815 is a universal AC/DC LED driver designed for LED lighting applications. The device can achieve high Power Factor values without resorting to additional circuits and can also generate high accuracy LED drive currents with very few external components. Separate grounds are provided. One is a floating ground for the device while the other is the earth terminal. Users should be aware that the two grounds cannot be directly connected together to avoid IC damage and system malfunction. The power MOSFET is turned on by inductor current zero-crossing detection. The current zero-crossing can be detected by a ZCD voltage. When the inductor current is at the zero crossing point, the voltage on the ZCD pin will drop rapidly. The device then detects the falling edge and turns on the internal power MOSFET. The boundary conduction mode provides for low turn-on switching losses and high conversion efficiency. Zero Current Detection – ZCD Start-up Current The ZCD voltage is designed to operate between 0V and 3V for normal operation. If the voltage on the ZCD pin goes higher than 1.5V, the ZCD comparator waits until the voltage goes below 1V. When the inductor current is at the zero crossing point, the voltage on the ZCD pin will drop rapidly. The device will then detect the 1V falling edge and turn on the Power MOSFET. The 0.5V hysteresis avoids any false triggering actions due to noise. A very low start-up current, ISTART, allows the users to select a larger value of start-up resistor which reduces power dissipation. VCC Under Voltage Lockout – UVLO The device includes a UVLO feature which has 8V hysteresis. The PWM controller turns on when VCC is higher than 18V and turns off when VCC is lower than 10V. The hysteresis characteristics guarantee that the device can be powered by an input capacitor during start-up. When the output voltage increases to a certain value after start-up, VCC will be charged by an output through an auxiliary winding or a Zener Diode. VZ=VLED - VCC. Rev. 1.00 5 June 26, 2015 Preliminary HT7L4815 Constant Current Control VOVP-ZCD can be set using the following equation: VOVP-ZCD = VZCDH+IOVP×RZCD The HT7L4815 will sense the overall inductor current and form a closed-loop with an internal error amplifier to obtain high constant current accuracy. The CS voltage and the 0.2V reference voltage form the inputs to an internal Gm amplifier whose output is integrated via an external COMP capacitor. The ON time of the MOSFET is controlled by the COMP voltage to adjust the output current. VZCDH is the 3V upper clamp voltage on the ZCD pin. IOVP represents the OVP current level on the ZCD pin which is 300μA. RZCD stands for the resistor connected between the ZCD pin and the LED positive terminal. OCP – Over Current Protection LEB on CS – Leading-Edge Blanking The device includes an over current protection function on the CS pin. An internal circuit detects the current level and when the current is larger than the over current protection threshold level, VOCP/RCS, the gate output will remain at a low level. Each time the internal power MOSFET is switched on, a turn-on spike will inevitably occur at the sense resistor. To avoid faulty triggering, a 400ns leadingedge blank time is generated. As this function is provided conventional RC filtering is therefore unnecessary. During this blanking period, the currentlimit comparator is disabled and can therefore not switch off the gate driver. LED Short Protection – SCP The output voltage drops when a number of LEDs in a string are shorted resulting in a voltage drop at VCC. Once the VCC drops below 10V, the device will stop operating. Under such situations, the start-up operation will recharge the VCC pin through the startup resistor and the device will enter the UVLO hiccup mode. OVP on VCC – Over Voltage Protection In order to prevent PWM controller damage, the device includes an OVP function on VCC. Should the VCC voltage be higher than the OVP threshold voltage of 29V, the PWM controller will stop operating immediately. When the VCC voltage decreases below the UVLO off level, the controller will reset. Thermal Protection A thermal protection feature is included to protect the device from excessive heat damage. When the junction temperature exceeds a threshold of 150°C, the thermal protection function will turn off the DRAIN terminal immediately. When the VCC decreases below the UVLO off level, the controller will reset. LED Open Protection – ZCD OVP The LED voltage is reflected on the ZCD pin through a resistor RZCD. When the current on the resistor RZCD is higher than 300μA, then ZCD OVP protection will take place. Here the PWM controller will stop operating immediately. When the VCC voltage decreases below the UVLO off level, the controller will reset. Rev. 1.00 6 June 26, 2015 HT7L4815 Package Information Note that the package information provided here is for consultation purposes only. As this information may be updated at regular intervals users are reminded to consult the Holtek website for the latest version of the package information. Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be transferred to the relevant website page. • Further Package Information (include Outline Dimensions, Product Tape and Reel Specifications) • Packing Meterials Information • Carton information Rev. 1.00 7 June 26, 2015 HT7L4815 8-pin SOP (150mil) Outline Dimensions Symbol Dimensions in inch Min. Nom. A — 0.236 BSC — B — 0.154 BSC — Max. 0.020 C 0.012 — C’ — 0.193 BSC — D — — 0.069 E — 0.050 BSC — F 0.004 — 0.010 G 0.016 — 0.050 H 0.004 — 0.010 α 0° — 8° Symbol Rev. 1.00 Dimensions in mm Min. Nom. Max. A — 6.00 BSC — B — 3.90 BSC — C 0.31 — 0.51 C’ — 4.90 BSC — D — — 1.75 E — 1.27 BSC — F 0.10 — 0.25 G 0.40 — 1.27 H 0.10 — 0.25 α 0° — 8° 8 June 26, 2015 HT7L4815 Copyright© 2015 by HOLTEK SEMICONDUCTOR INC. The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. Holtek's products are not authorized for use as critical components in life support devices or systems. Holtek reserves the right to alter its products without prior notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.tw. Rev. 1.00 9 June 26, 2015