A/B G2610 Global Mixed-mode Technology Inc. High Efficiency, Constant Current 40V, 1A LED Driver with Internal Switch Feature Description Operating Voltage: 7V to 40V Output driving current up to 1A (1 × LED) Internal PWM filter Shutdown Current <20μA (Typ) Digital Dimming Control Thermal Overload Protection Open/Shorted LED Protection SOT-23-5 Package The G2610 is a step-down converter, designed for driving high-brightness LED. The device operates over a 7V to 40V input voltage and driving current from few milliamps up to 1A. The device built-in Overload Protection to prevent operating fails condition. Application GPS Navigation System Compact Back Light Module Constant Current Source LED Module Ordering Information ORDER NUMBER G2610T11U Note: T1: SOT23-5 1: Bonding Code MARKIMG TEMP. RANGE PACKAGE (Green) 2610x -40°C to +85°C SOT-23-5 U: Tape & Reel Pin Configuration Typical Application Circuit D1 CS=0.1µF (Option) G2610 LX 1 GND 2 5 RS=0.1Ω VIN VIN=7V~40V VIN CIN=4.7µF SHDN 4 3 LX CDC=0.1µF GND SENSE SENSE L1=47µH SHDN SOT-23-5 *The PCB layout of G2610 must be carefully designed, otherwise the SENSE pin would be disturbed. An optioned 0.1µF decoupling capacitor(Cs) between VIN and SENSE is suggested, please place it as closely to VIN and SENSE as possible. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 1 A/B G2610 Global Mixed-mode Technology Inc. Absolute Maximum Ratings*1 SOT-23-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.5W Operating Temperature Range . . . . . . . .-40°C to +85°C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 150°C Storage Temperature Range . . . . . . . . .-65°C to +125°C Reflow Temperature (soldering, 10sec) . . . . . . . . 260°C ESD Susceptibility*2. HBM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV MM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200V LX to GND . . . . . . . . .-0.3V to +40V (42V for 0.5sec) VIN to GND . . . . . . . .-0.3V to +40V (42V for 0.5sec) SENSE to GND . . . . .-0.3V to +40V (42V for 0.5sec) SHDN to GND. . . . . . . . . . . . . . . . . . . . .-0.3V to +6V Switch Current (ILX) . . . . . . . . . . . . . . . . . . . . . . .1.5A Thermal Resistance Junction to Ambient, (θJA)* SOT-23-5 . . . . . . . . . . . . . . . . . . . . . . . . . . 250°C/W Continuous Power Dissipation (TA = +25°C)* * Please refer to “Minimum Footprint PCB Layout Section”. 1. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2. Device are ESD sensitive. Handling precaution recommended. The Human Body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. 3. Depending on PC board layout. Electrical Characteristics (VIN=12V, L=47µH, 1*LED, LED Current=330mA, TA=+25°C.) The device is not guaranteed to function outside its operating conditions. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Parameter Input Voltage Under Voltage Threshold Quiescent supply current with output off Symbol Condition VIN VSU VSD IQoff Quiescent supply current with output IQon switching Mean current sense threshold VSENSE voltage(Defines LED current setting Bin1 accuracy) Mean current sense threshold VSENSE voltage(Defines LED current setting Bin2 accuracy) Sense threshold hysteresis VSENSEHYS Maximum LED average current SENSE pin input current Temperature coefficient of VREF LX Switch on resistance LX switch leakage current IMLED Typ. Max. Unit VIN rising. VIN falling. 7 ----- --6.0 5.55 40 ----- V V V SHDN pin grounded. --- 20 40 µA SHDN pin floating, f=250kHz. --- 1.8 5.0 mA 100 103 106 mV 94 97 100 mV --- ±15 --- % --- --- 1 A ----- 5 50 10 --- µA ppm/k ----- 0.5 1 1.0 5 Ω µA --- 600 --- kHz 1.5 ----------- ----10 --150 30 --0.5 --5 ----- V V mS µA °C Measured on SENSE pin with respect to VIN. L=47µH, IOUT=330mA. Measured on SENSE pin with respect to VIN. L=47µH, IOUT=330mA. L=47µH, NOTE (1) ISENSE VSENSE=VIN-0.1V ΔVREF/ΔT RLX ILX(leak) Operating frequency fLX Logic High Logic Low SHDN low shutdown delay SHDN Input current Thermal Shutdown Thermal Shutdown Hysteresis VIH VIL --ISD Tsd --- SHDN Input level Min. LX switch ON resistance. LX switch leakage current. SHDN floating, L=47µH, IOUT=330mA. VSHDN=0V. °C NOTE (1). The power dissipation of the SOT-23-5 must be lower than 0.3W at 70°C. Suggest the number of LEDs should be one only, when LED average current is 1000mA. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 2 A/B G2610 Global Mixed-mode Technology Inc. Typical Characteristics Condition: VIN=12V, L=47µH, CIN=10µF and 0.1µF, 1*LED, LED Current=1000mA. Soft-start Power on CH1: EN Voltage(2V/div), CH2: LX Voltage(10V/div) CH3: Input Current(500mA/div), CH4: LED Current(1A/div) (100us/div) CH1: Input Voltage(10V/div), CH2: LX Voltage(10V/div) CH3: Input Current(500mA/div), CH4: LED Current(1A/div) (2ms/div) Power off LED Current Ripple CH1: Input Voltage(10V/div), CH2: LX Voltage(10V/div) CH3: Input Current(500mA/div), CH4: LED Current(1A/div) (2ms/div) CH1: LX Voltage(10V/div), CH4: LED Current(100mA/div) (2us/div) Input Voltage is Electronic transformer (AC=12V) Dimming Control Dimming Frequency=100Hz, Duty=50% CH1: Input Voltage(10V/div), CH2: LX Voltage(10V/div) CH4: LED Current(500mA/div) (5ms/div) CH1: EN Voltage(2V/div), CH2: LX Voltage(20V/div) CH3: Input Current(500mA/div), CH4: LED Current(1A/div) (5ms/div) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 3 A/B G2610 Global Mixed-mode Technology Inc. Typical Characteristics Condition: VIN=12V, L=47µH, CIN=10µF and 0.1µF, 1*LED, LED Current=1000mA. Vsense vs. Input Voltage Vsense vs. LED Current ILED=350mA ILED=700mA ILED=1000mA 7 Vsense vs. LED Current 110 108 106 104 102 100 98 96 94 92 90 Vsense(mV) Vsense(mV) Vsense vs. Input voltage 110 108 106 104 102 100 98 96 94 92 90 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 VIN(V) 100 200 300 Vsense vs. Temperature Vsense vs. T emperature Vsense(mV) Vsense(mV) 100 98 96 94 92 90 -20 0 20 40 Ta(°C) 60 80 600 700 800 900 1000 100 Vsense vs. Inductor 105 104 103 102 101 100 99 98 97 96 95 120 10 Shutdown Current vs. Input Voltage 22 33 47 Inductor(uH) 68 100 MOSFET Rds(on) vs. LED Current Shutdown Current vs. Input voltage Ron vs. LED Current 0.5 19 17 0.45 15 Ron(Ω) Ishdn(uA) 500 ILED(mA) Vsense vs. Inductor 104 102 -30 400 13 11 9 0.4 0.35 7 5 0.3 7 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 VIN(V) 100 200 Vsense vs. PWM Dimming 300 400 Vsen se(m V) Vsen se(m V) 20 30 40 50 800 900 1000 Vsense vs Duty Dimming frequency=100Hz 10 700 Vsense vs. PWM Dimming Vsense vs Duty 100 90 80 70 60 50 40 30 20 10 0 0 500 600 Iout(mA) 60 70 80 90 100 100 90 80 70 60 50 40 30 20 10 0 Dimming frequency=1kHz 0 Duty(%) 10 20 30 40 50 60 70 80 90 100 Duty(%) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 4 A/B G2610 Global Mixed-mode Technology Inc. Typical Characteristics Condition: VIN=12V, L=47µH, CIN=10µF and 0.1µF, 1*LED, LED Current=1000mA. Efficiency (LED Current=330mA) 2*LED 8*LED 3*LED 4*LED Efficiency (LED Current=650mA) 5*LED 6*LED 1*LED 7*LED 100.00 100.00 95.00 95.00 90.00 90.00 Efficiency(%) Efficiency(%) 1*LED 7*LED 85.00 80.00 75.00 2*LED 8*LED 3*LED 4*LED 5*LED 6*LED 85.00 80.00 75.00 70.00 70.00 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 VIN(V) VIN(V) Efficiency (LED Current=1000mA) 1*LED 7*LED 2*LED 8*LED 3*LED 4*LED 5*LED 6*LED 100.00 Efficiency(%) 95.00 90.00 85.00 80.00 75.00 70.00 0 5 10 15 20 VIN(V) 25 30 35 40 Minimum Footprint PCB Layout Section SOT-23-5 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 5 A/B G2610 Global Mixed-mode Technology Inc. Pin Description Pin No. Symbol 1 LX 2 GND, PGND 3 SHDN 4 SENSE 5 VIN Descript Step-down Regulator N-MOS Drain. Place output diode and inductor. Ground. Dimming and Shutdown pin. 1. For automatic startup, leave SHDN unconnected. 2. Drive to voltage below 0.5V to turn off LED Current. Connect resistor Rs from this pin to VIN to define nominal average output current. Input Voltage. Block Diagram TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 6 A/B Global Mixed-mode Technology Inc. G2610 General Description Shutdown Control Digital logic of SHDN provides an electrical ON/OFF control of the power supply. Connecting this pin to ground or to any voltage less than 0.6V and sustain the level over 10ms will completely turn off the regulator. In this state, current drain from the input supply is less than 20µA (Typ.), the internal reference, error amplifier, comparators, and biasing circuitry turn off. If holding time of low level is less than 10ms on this pin, then the device only shutdown driver logic block. Dimming Control Digital logic of SHDN also provides LEDs brightness control by applying a PWM signal on SHND pin. With this way, the LEDs operate with either zero or full current. The average LED current is proportional to the duty-cycle of the PWM signal. Typical PWM frequency should be between 100Hz to 1kHz. If dimming control is not required, SHDN works as a simple on/off control. Thermal Shutdown Thermal-overload protection limits total power dissipation in the G2610. When the junction temperature exceeds Tj=150°C, a thermal sensor activates the thermal protection, which shutdowns the IC, allowing the IC to cool. Once the device cools down by 30°C, IC will automatically recover normal operation. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 7 A/B G2610 Global Mixed-mode Technology Inc. Application Information Programming average LED current The sense resistor (Rs) and the sense voltage (VIN-Vsense) control the LED average current. 0 .1 Rs ILED = LED Current (mA) Rs(Ω) 350mA 0.285 700mA 0.142 1000mA 0.1 In order to have accurate LED current, precision resistors are preferred (1% is recommend). Operating Frequency fs = 1 TON + TOFF Where: fs is operating frequency TON is LX on time TOFF is LX off time LX on time TON = L ΔI L VIN − VLED − ILED (Rs + rL + R LX( ON) ) TONmin>250ns LX off time TOFF = VLED LΔIL + VD + ILED (Rs + rL ) TOFFmin>250ns Where: VIN is the Input Voltage VLED is the total LED forward voltage ILED is the LED average current RS is the current sense resistance rL is the inductor resistance RLX(ON) is the LX on resistance (0.5Ω typ.) L is the inductance ΔIL is the inductor peak-peak current (internally set to Iavg× 0.3) VD is the diode forward voltage at the LED average Current Recommend operating frequency not more than 1MHz. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 8 A/B Global Mixed-mode Technology Inc. G2610 Power Dissipation Calculation Power dissipation of the G2610 comes from four sources: N-MOSFET power dissipation, Diode dissipation, Input quiescent current, and Rs dissipation. The power dissipation of high side N-MOSFET: PN−MOSFET = I2 RMS × R DS(on)−N + ( ) 1 × (VIN + VD ) × IL(peak) × t r + IL(Low) × t f × f s 2 RDS(on)-N is resistance of the N-MOSFET. IL(peak) is peak value of the inductor current. IL(low) is low value of inductor current. fs is the switching frequency. tr is the switching rise time, typically<20ns. tf is the switching fall time, typically<20ns. The RMS value of the N-MOSFET: IRMS = ΔIL = (I 2 L ( peak ) ) + IL(peak ) × IL(low ) + I2 L(low ) × D 3 VIN − Vsense − VLED DTs L 1 ΔIL 2 1 − ΔIL 2 IL(peak ) = ILED + IL(low ) = ILED Quiescent current dissipation: PQ = VIN × IQ = VIN × [ IQon × D + IQoff (1 − D)] G2610 inside dissipation: PIC = PN−MOSFET + PQ Diode dissipation, and Rs dissipation: PL = ILED × VD × (1 − D ) + ILED × Rs 2 Power total dissipation: Pt = PIC + PL D is duty cycles. IQ is the quiescent current. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 9 A/B G2610 Global Mixed-mode Technology Inc. Example VIN=12V, L=47µH, fs=600kHz, Duty=30%, Rs=0.28Ω, RDS(ON)=0.5Ω, VD=0.4V, VSENSE=0.1V, VLED=3.2V, ILED=350mA, IQon=1.8mA, IQoff=20µA, tr=20ns, tf=15ns IL(peak ) = ILED + IL(low ) = ILED − IRMS = ΔIL 12 − 0.1 − 3.2 1 = 0.35 + × 0 .3 × = 396.28mA −6 2 2 × 47 × 10 600 × 103 ΔIL = 303.72mA 2 (396.28 2 ) + 396.28 × 303.72 + 303.722 × 0.3 = 192.26mA 3 PN−MOSFET = 0.19226 2 × 0.5 + ( ) 1 (12 + 0.4) × 0.39628 × 20 × 10−9 + 0.30372 × 15 × 10−9 × 600 × 103 2 = 0.065 W PQ = 12 × [1.8 × 10 −3 × 0.3 + 20 × 10 −6 (1 − 0.3 )] = 6.65mW PIC = 0.065 + 0.00665 = 0.07165 W PL = 0.35 × 0.4 × (1 − 0.3 ) + 0.35 2 × 0.28 = 0.1323 W Pt = 0.07165 + 0.1323 = 0.20395W Diode Selection When the LX switch turns off, the current through the inductor continues to flow. The path for this current is through the diode connected between the LX switch and VIN. This forward biased diode must has a minimum voltage drop and recovery times. Schottky diode is recommended and it should be able to handle those current. As usual, the reverse voltage rating of the diode should be at least 1.3 times greater than the maximum input voltage, and current rating is greater than the maximum load current. Diode Open If the diode (D1) is open circuit, the energy stored in the inductor will drive LX voltage higher. The chip will be damaged if LX voltage higher than 40V. The diode can not be opened in use. Input Capacitor An input capacitor (CIN) helps to provide additional current to the power supply as well as smooth input voltage variations in high current switching regulators. When selecting an input capacitor, a low ESR capacitor is required to keep the noise at the IC to a minimum. Ceramic capacitors are preferred, but tantalum or low-ESR electrolytic capacitors may also suffice. Choose an input capacitor with maximum voltage rating is 1.3 times greater than the maximum input voltage, and RMS current rating is equal to one-half of the maximum dc load current. It may be necessary in some designs to add a small valued ceramic type capacitor in parallel with the input capacitor to prevent any ring. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 10 A/B Global Mixed-mode Technology Inc. G2610 Decoupling Capacitor This is the decoupling capacitor (CDC) for the input voltage to the internal circuit. Use a 0.1μF capacitor and place it as closely to the VIN and GND pins as possible. Inductor Selection Recommended inductor (L1) values for the G2610 are in the range 22μH to 100μH. Once an inductance value is determined from the frequency equation, the maximum operating current must be verified. Although peak-to-peak ripple current is controlled by the hysteresis value, there is some variation due to propagation delay. This means that the inductance has a direct effect on LED current line regulation. In general, a larger inductor will result in lower frequency and better line regulation. PC Board Layout 1. The most critical aspect of the layout is the placement of the decoupling capacitor (CDC) and input capacitor (CIN). It must be placed as close as possible to the G2610 to reduce the input ripple voltage. 2. Power loops on the input and output of the converter should be laid out with the shortest and widest traces possible. The longer and narrower the trace, the higher resistance and inductance it will have. The length of traces in series with the capacitors increases its ESR and ESL and reduces their effectiveness at high frequency. 3. The SENSE pin should connect to sense resistors directly. And the route should be away from the noise source, such as inductor of LX line. Sense resistors must be placed as close as to the sense pin. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 11 A/B G2610 Global Mixed-mode Technology Inc. Package Information SOT-23-5 Package Taping Specification PACKAGE Q'TY/REEL SOT-23-5 3,000 ea GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at any time without notice to change said circuitry and specifications TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 0.2 Nov 30, 2009 12