AMC7150

AMC7150 www.addmtek.com DESCRIPTION AMC7150 is a PWM power LED driver IC. The driving current from few milliamps up to 1.5A. It allows high brightness power LED operating at high efficiency from 4Vdc to 40Vdc. Up to 200KHz external controlled operation frequency. External resistor controlled the maximum output current to single LED or a LED string. 1.5A POWER LED DRIVER FEATURES Only 5 external components required. Output driving current up to 1.5A. 4V~40V wide operation voltage range. High efficiency ESD protection HBM 2KV TO-252 5-pin power package. APPLICATIONS DC/DC LED driver Automotive Lighting PACKAGE PIN OUT 5 4 3 2 1 OSC OUT GND CS VCC TO-252-5L (Top View) TYPICAL APPLICATION 4V~40V Rsense VCC CIN OSC CS OUT DF L AMC7150 GND CT DL ORDER INFORMATION TO-252 5-pin AMC7150DL AMC7150DLF (Lead Free) Note: 1. All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e. AMC7150DLT). 2. The letter ”F” is marked for Lead Free process. Copyright © 2006 ADDtek Corp. 1 DD034_A -- JUNE 2006 AMC7150 POWER DISSIPATION TABLE Package DL DLF θJA O ( CW) 80 80 TA=70 OC TA= 85OC Derating factor ( mW/OC ) TA≦25 OC TA≧25 OC Power rating (mW) Power rating (mW) Power rating (mW) 12.5 1560 1000 812 12.5 1560 1000 812 Note : Junction Temperature Calculation: TJ = TA + (PD x θJA). PD: Power Dissipation, TA: Ambient temperature, θJA: Thermal Resistance-Junction to Ambient The θJA numbers are guidelines for the thermal performance of the device/PC-board system. All of the above assume no ambient airflow. BLOCK DIAGRAM 4V~40V VCC Rsense CS 330mV OUT L CIN DRIVER CONTROL OSC DF OSC CT GND AMC7150 Copyright © 2006 ADDtek Corp. 2 DD034_A -- JUNE 2006 AMC7150 PIN DESCRIPTION Pin Number 1 2 3 4 5 Pin Name VCC CS GND OUT OSC Input Voltage 4V ~ 40V Peak current senses pin. Ground Driver output pin. Oscillator timing capacitor. Pin Function ABSOLUTE MAXIMUM RATINGS Input Voltage, VCC Output Voltage, OUT Maximum Junction Temperature , TJ Storage Temperature Range Lead Temperature (soldering, 10 seconds) Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. -0.3V to 40V -0.3V to 40V 150OC -40OC to 150OC 260OC RECOMMENDED OPERATING CONDITIONS Parameter Symbol Min Typ Supply Voltage VCC 4 Output current IOUT Operating free-air temperature range Ta -40 Max 40 1.5 85 Unit V A ℃ ELECTRICAL CHARACTERISTICS VCC=5V, Ta=25°C. ( Unless otherwise noted) Parameter Supply Current Output Drop-out Voltage Output Off Current Current Sense Voltage Maximum duty cycle OSC Charge Current Symbol ICC VDP IOFF VCS TDC ICH Condition VCC=4~40V IOUT=1A, VCS-VOUT VCS-VOUT= 40V VCC- VCS VCS=VCC 300 1 200 330 85 35 Min Typ Max 4 1.31 300 360 Unit mA V µA mV % uA Apply Pin VCC OUT CS OSC Copyright © 2006 ADDtek Corp. 3 DD034_A -- JUNE 2006 AMC7150 APPLICATION INFORMATION Low Voltage DC/DC Application The AMC7150 was designed for power LED driving application. Only 5 external components were required for low voltage application. Fig.1 shows the typical application circuit for input voltage range from 4V to 40V. Buck power conversion topology was used and total forward voltage (at expecting current) of the LED string should lower than supply voltage by 1.6V at least. 4V~40V Rsense VCC CIN OSC CS OUT DF L AMC7150 GND CT Input Bypass Capacitor The input by-pass capacitor CIN holds the input voltage and filters out the switching noise of AMC7150. Flywheel Diode The fast recovery diode was recommended for flywheel diode DF. This is because the high reverse recovery current will cause the voltage drop across Rsense being higher than 330mV, and consequently the switch will be turned off which has just been turned on. LED Driving Current The peak current IPK flow though LEDs was decided by: I PK = 330mV Rsense The average current on LEDs was determined by the peak-to-peak ripple current that was decided by inductor L. Assume the target average current 550mA on LEDs and ripple current 100mA then the Rsense should be: Rsense = 330mV = 0.55Ω 550mA + 0.5 ⋅ 100mA The Rsense value should higher than 200mΩ so that driving current won’t over the recommended maximum driving current 1.5A. Copyright © 2006 ADDtek Corp. 4 DD034_A -- JUNE 2006 AMC7150 Inductor The Inductor L stores energy during switch turn-on period and discharge driving current to LEDs via flywheel diode while switch turn-off. In order to reduce the current ripple on LEDs, the L value should high enough to keep the system working at continuous-conduction mode that inductor current won’t fall to zero. Since in steady-state operation the waveform must repeat from one time period to the next, the integral of the inductor voltage vL over one time period must be zero: ∫ Ts 0 v L dt = ∫ v L dt + ∫ v L dt = 0 0 tON tON Ts Where Ts = t ON + t OFF Therefore t ON VLED + VF = t OFF VCC − VRsense − VSAT − VLED Where, VLED is the total forward voltage (at expecting current) of the LED string, VF is the forward voltage of the flywheel diode DF, VRsense is the peak value of the voltage drop across Rsense which is 300mV, and VSAT is the saturation voltage of the switch which has a typical value of 1V. Since the operation frequency f is determined by choosing appropriate value for timing capacitor CT, the switch turn-on time can also be known by t ON = D ⋅ Ts = D f Where D( Dutycycle) = t ON t ON + t OFF With knowledge of the peak switch current and switch on time, the value of inductance can be calculated. L= VCC − VRsense − VSAT − VLED ⋅ t ON I PK Copyright © 2006 ADDtek Corp. 5 DD034_A -- JUNE 2006 AMC7150 PACKAGE ‧ 5-Pin Surface Mount TO-252 ( DL ) Copyright © 2006 ADDtek Corp. 6 DD034_A -- JUNE 2006 AMC7150 IMPORTANT NOTICE ADDtek reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. ADDtek integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of ADDtek products in such applications is understood to be fully at the risk of the customer. In order to minimize risks associated with the customer’s applications, the customer should provide adequate design and operating safeguards. ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of its products to the specifications applicable at the time of sale. ADDtek Corp. 9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105 TEL: 2-25700299 FAX: 2-25700196 Copyright © 2006 ADDtek Corp. 7 DD034_A -- JUNE 2006