® RT8541/A 90V Boost DC/DC Converter with APD Current Monitor General Description Features The RT8541/A is a constant frequency current mode PWM step-up DC/DC converter designed to bias avalanche photodiodes (APD) at high voltage in optical receivers. It includes a voltage doubler charge pump to significantly reduce the noise level at output up to 90V. The RT8541A switching frequency can be adjusted by a resistor while RT8541 is internally set at 650kHz. The RT8541/A has a built-in APD current mirror that delivers 1/5 of the APD current with high accuracy for monitoring the APD current from 0.25μA to 2.5mA. This current can be used as a reference to provide a digital programmed output voltage via the CTRL pin. To protect the optical receiver system, the RT8541/A provides a built-in adjustable APD current limit function by sensing a 200mV voltage threshold between VOUT2 and MONIN pins. Only one resistor is needed to program the desired current limit. A charge pump voltage doubler is designed to achieve significantly lower noise level at the APD comparing to a simple boost converter type bias circuit. Integrated Schottky Diodes for Charge Pump Voltage Doubler 50V, 400mA Internal Switch High Side Low Noise and Accurate APD Current Monitor 650kHz Fixed Switching Frequency for RT8541 and Adjustable Switching Frequency for RT8541A Wide VIN Range : 2.7V to 16V Adjustable APD Current Limit with External Resistor Low Shutdown Current <1μ μA Built-In Soft-Start CTRL Pin Allows Output Adjustment with no Polarity Inversion Thin 16-Lead WQFN Package RoHS Compliant and Halogen Free The RT8541/A also features a built-in 9ms soft-start function to eliminate the inrush current during start-up interval. The RT8541/A provides a low cost optical receiver solution and can fit in very small PCB area. Applications APD Bias PIN Diode Bias Optical Receivers and Modules Fiber Optic Network Equipment The RT8541/A is available in the WQFN-16L 3x3 package. Simplified Application Circuit C1 L VIN CIN R5 VOUT COUT VOUT1 CFB C3 RSET GND Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 R6 C2 VC FSET R4 C4 SW PUMP VIN RT8541/A MONIN CTRL SHDN VOUT2 FB MON APD R3 R2 R1 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8541/A Ordering Information Pin Configurations RT8541/A (TOP VIEW) Lead Plating System G : Green (Halogen Free and Pb Free) Adjustable Switching Frequency Fixed Switching Frequency MON NC FB CTRL Package Type QW : WQFN-16L 3x3 (W-Type) 16 15 14 13 VC APD MONIN VOUT2 1 12 2 11 GND 3 Note : 9 5 RoHS compliant and compatible with the current require- Suitable for use in SnPb or Pb-free soldering processes. 6 7 8 VOUT1 PUMP SW SW Richtek products are : 10 17 4 SHDN VIN GND GND ments of IPC/JEDEC J-STD-020. WQFN-16L 3x3 MON FSET FB CTRL RT8541 Marking Information RT8541GQW 16 15 14 13 8C= : Product Code 8C=YM DNN YMDNN : Date Code VC APD MONIN VOUT2 1 12 2 11 GND 3 9 1G= : Product Code 1G=YM DNN YMDNN : Date Code Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 6 7 8 VOUT1 PUMP SW SW 5 RT8541AGQW 10 17 4 SHDN VIN GND GND WQFN-16L 3x3 RT8541A is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A Functional Pin Description Pin No. Pin Name Pin Function 1 VC Compensation Node for Control Loop. 2 APD Output for APD. Connect this Pin to the APD Cathode. 3 MONIN Current Monitor Input Power Pin. An optional resistor between the VOUT2 and MONIN pins can be used for current limit setting. 4 VOUT2 Voltage Doubler Output Pin. A 50V rated capacitor is needed between this pin and VOUT1 pin. A resistor divider for output voltage feedback is connected between this pin and GND pin. 5 VOUT1 6 PUMP 7, 8 SW Output Pin of Boost Converter. A capacitor is needed between this pin and GND pin. The trace length from this pin to the capacitor should be minimized. Charge Pump Pin for Voltage Doubler. Put a 50V capacitor between the SW and PUMP pins to form a complete voltage doubler with the internal Schottky diodes. Switch Node of Boost Converter. Minimize the trace area on this pin to reduce EMI. A Schottky diode between SW pin (cathode) and GND pin (anode) is required Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 9, 10, 17 (Exposed Pad) GND 11 VIN 12 SHDN 13 CTRL 14 FB Feedback Input. Connect the pin to the output resistor divider for output voltage setting. NC (RT8541) No Internal Connection. The switching frequency is set at 650kHz internally. FSET (RT8541A) Oscillator Frequency Setting. Connect a resistor between this pin and GND for frequency setting. MON Output for Current Monitor. It sources a current equal to 20% of the APD current and converts to a reference voltage through an external resistor. 15 16 Supply Voltage Input. Connect a 1F capacitor from this pin to GND. Shutdown Control Input. Tie to 2V or higher with a resistor 200k to enable device. External Reference Control Input. This allows the FB voltage to follow the external reference between 0V and 1.2V. Tie this pin higher than 1.5V to use the internal reference of 1.235V. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8541/A Function Block Diagram VIN SHDN SW PUMP D3 VOUT2 1.235V Reference CTRL FB Soft-Start D1 D2 VOUT1 + + A1 Error Amplifier R A2 + PWM Comparator Q1 Q S VC + Oscillator Current Sense Amplifier APD Current Mirror APD MON MONIN APD Current Limit 0.2V + GND FSET (RT8541A Only) Operation The RT8541/A Boost converter uses a constant frequency current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Functional Diagram. At the start of each oscillator cycle, the SR latch is set, which turns on the power switch, Q1. A voltage proportional to the switch current is added to a stabilizing slope compensation and the resulting sum is fed into the positive terminal of the PWM comparator, A2. When this voltage exceeds the level at the negative input of A2, the SR latch is reset and the power switch is turned off . The level at the negative input of A2 is set by the error amplifier A1, and is simply an amplified version of the difference between the feedback voltage and the reference voltage of 1.235V, or externally provided CTRL voltage. In this manner, the error amplifier sets the correct peak current level to keep the output in regulation. If the error amplifier's output increases, more current is delivered to the output; if it decreases, less current is delivered. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 The RT8541/A has an integrated high side APD current monitor with a 5:1 ratio. The MONIN pin can accept a supply voltage up to 90V, which is suitable for APD photodiode applications. The MON pin has an open-circuit protection feature and is internally clamped to 15V. If an APD is tied to the APD pin, the current will be mirrored to the MON pin and converted to a voltage signal by the resistor between MON and GND pins. This voltage signal can be used to drive an external control block to adjust the APD voltage by adjusting the feedback threshold of Error Amplifier A1 through the CTRL input. The RT8541/A features a built-in 9ms soft-start function and provides current limit function with a 0.2V threshold between VOUT2 and MONIN pins to protect the APD system. The APD current limit can be adjusted by an external resistor between the VOUT2 and MONIN pins. is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A Absolute Maximum Ratings (Note 1) VIN, SHDN, FSET, CTRL, MON ---------------------------------------------------------------------------------------VOUT1, SW ----------------------------------------------------------------------------------------------------------------VOUT2, PUMP, MONIN, APD ------------------------------------------------------------------------------------------FB, VC, FSET --------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C 16V 50V 90V 5V WQFN-16L 3x3 ------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WQFN-16L 3x3, θJA -------------------------------------------------------------------------------------------------------WQFN-16L 3x3, θJC ------------------------------------------------------------------------------------------------------Junction Temperature -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ----------------------------------------------------------------------------------------------MM (Machine Model) ------------------------------------------------------------------------------------------------------ 3.33W Recommended Operating Conditions 30°C/W 7.5°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage, VIN ------------------------------------------------------------------------------------------------ 3V to 12V Junction Temperature Range --------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range --------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 5V, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit 2.7 -- 16 V 1.215 1.235 1.255 V -- 0.025 0.07 %/V -- 30 100 nA FB = 1.3V, VSHDN = 2V -- 3.3 4 mA VSHDN = 0V, Not Switching -- 0.1 0.5 A RSET = NC (RT8541) -- 650 -- RSET = 30k (RT8541A) -- 650 -- fSW = 650kHz 95 -- -- % 320 400 480 mA Operating Voltage Feedback Voltage VFB Feedback Line Regulation CTRL = 1.5V VIN = 3V to 10V FB Pin Bias Current Supply Current IVIN Shutdown Current Switching Frequency fSW Maximum Duty Cycle DMAX Switch Current Limit ILIM kHz Switch VCESAT ISW = 150mA -- 130 220 mV Switch Leakage Current SW = 5V -- -- 2 A Schottky Forward Voltage ISCHOTTKY = 150mA -- 720 -- mV Schottky Reverse Leakage VOUT1 SW = 50V -- -- 5 A Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8541/A Parameter Symbol Test Conditions Min Typ Max Unit SHDN Voltage High VIH 2 -- -- V SHDN Voltage Low VIL -- -- 0.4 V SHDN Pin Bias Current -- 1 2 A Internal Soft-Start Time -- 9 -- ms VC Threshold Voltage -- 0.7 -- V IAPD = 250nA, 10V MONIN 90V 0.18 0.2 0.22 IAPD = 2.5mA, 20V MONIN 90V 0.18 0.2 0.22 -- 15 16 V APD Current Monitor Gain GAPD Monitor Output Voltage Clamp -- APD Monitor Voltage Drop MONIN APD at IAPD = 1mA, MONIN = 90V -- -- 5 V MONIN Pin Current Limit Threshold Voltage APD = 0V, MONIN = 40V -- 200 -- mV CTRL to FB Offset CTRL = 0.5V 5 2 12 mV -- 150 -- C OTP Threshold Temperature Note 1. Stresses beyond those listed “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 may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A Typical Application Circuit L 10µH VIN 3.3V C1 0.1µF 7, 8 6 SW PUMP 11 VIN RT8541 3 13 MONIN CTRL 4 R5 200k 12 VOUT2 SHDN CIN 1µF On Off 1 VC VOUT1 R4 51k C4 3.3nF 9, 10, 17 (Exposed Pad) VIN 3.3V VOUT COUT 70V (Max.) 0.1µF CFB 10nF R2 1M R1 16.5k R3 10k C1 0.1µF 7, 8 6 SW PUMP 11 VIN RT8541A 3 13 MONIN CTRL 4 R5 200k 12 VOUT2 SHDN CIN 1µF On Off C2 0.47µF C3 0.47µF FB 14 16 MON APD 2 GND L 10µH 5 R6 100 1 R4 51k C4 3.3nF 15 VC VOUT1 FSET RSET 30k 9, 10, 17 (Exposed Pad) 5 C2 0.47µF C3 0.47µF VOUT COUT 70V (Max.) 0.1µF CFB 10nF FB 14 MON 16 APD 2 GND R6 100 R2 1M R1 16.5k R3 10k Figure 1. 3.3V to 63V/2mA APD Bias Power Supply Application Circuit Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8541/A Typical Operating Characteristics Switching Frequency vs. Input Voltage Switching Frequency vs. Temperature 700 Switching Frequency (kHz)1 Switching Frequency (kHz) 1 1000 900 800 700 600 500 400 VIN = 3.3V 300 690 680 670 660 650 640 630 620 610 600 -50 -25 0 25 50 75 100 125 3 6 9 18 21.0 Current Monitor Output (µA)1 800 700 600 500 400 300 20.5 20.0 19.5 VIN = 3.3V IAPD = 0.1mA 19.0 200 -50 -25 0 25 50 75 100 10 125 20 30 40 50 60 70 80 90 MONIN Voltage (V) Temperature (°C) MON Current vs. APD Current Switch Saturation Voltage vs. Switch Current 450 350 300 250 200 150 100 50 VMON = 40V 0 Switch Saturation Voltage (mV)1 400 400 MON Current (µA) 15 Current Monitor Output vs. MONIN Voltage Switch Current Limit vs. Temperature 900 Switch Current Limit (mA) 12 Input Voltage (V) Temperature (°C) 350 300 250 200 150 100 50 VIN = 3.3V 0 0 500 1000 1500 APD Current (µA) Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 2000 0 100 200 300 400 Switch Current (mA) is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A FB Voltage vs. Temperature Switching Frequency vs. Resistor 1.200 Switching Frequency (kHz)1 2000 FB Voltage (V) 1.195 1.190 1.185 1.180 1660 1320 980 640 VIN = 3.3V 1.175 300 -50 -25 0 25 50 75 100 125 10 20 40 50 60 Resistor (Ω) Temperature (°C) Efficiency vs. APD Current Input Watt vs. APD Current 50 0.45 45 0.40 40 0.35 35 Input Watt (W) Efficiency (%) 30 30 25 20 15 0.30 0.25 0.20 0.15 0.10 10 5 VIN = 3.3V, VOUT = 63V 0 0.05 VIN = 3.3V, VOUT = 63V 0.00 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 APD Current (mA) APD Current (mA) FB Voltage vs. CTRL Voltage Monitor Step Response 2.5 1.4 FB Voltage (V) 1.2 VAPD_ac (500mV/Div) 1.0 0.8 0.6 VMON_ac (2V/Div) 0.4 0.2 VIN = 3.3V IAPD = 2mA, R3 = 10kΩ 0.0 0 0.25 0.5 0.75 1 1.25 1.5 Time (50ns/Div) CTRL Voltage (V) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8541/A Application Information Boost Regulator The RT8541/A is a current mode Boost converter integrated with a 50V/400mA power switch over a wide VIN range from 2.8V to 16V. It performs fast transient responses to support the avalanche photodiodes (APDs) in optical receivers. The high operation frequency allows the use of small components to minimize the thickness of the optical transceiver. The output voltage can be adjusted by an external resistive voltage divider connected to the FB pin. The error amplifier varies the VC voltage by sensing the FB pin to regulate the output voltage. For better stability, the slope compensation signal summed with the current sense signal will be compared with the VC voltage to determine the current trip point and duty cycle. where η is the efficiency of the converter, IIN(MAX) is the maximum input current. The input peak current can then be obtained by adding the maximum input current with half of the inductor ripple current. IPEAK =1.2 x IIN(MAX) Note that the saturated current of the inductor must be greater than IPEAK. The inductance can eventually be determined according to the following equation : VIN VOUT2 VIN 2 L= 0.4 VOUT2 IAPD fSET 2 where fSET is the switching frequency. For better system performance, a shielded inductor is preferred to avoid EMI problems. Switching Frequency Output Voltage Setting The RT8541/A regulated output voltage is showed as the following equation : VOUT = VFB 1 R1 , where VFB = 1.235V (typ.) R2 The recommended value for R2 should be at least 10kΩ. Place the resistive voltage divider as close as possible to the chip to reduce noise sensitivity. Loop Compensation The voltage feedback loop can be compensated with an external compensation network consisting of R4. Choose R4 to set high frequency integrator gain for fast transient response and C4 to set the integrator zero to maintain loop stability. For example, VIN = 3.3V, VOUT2 = 63V, COUT = 0.22μF, L = 6.8μH, the recommended value for the compensation network is R4 = 1kΩ and C4 = 3.3nF. The RT8541A FSET frequency adjust pin allows the user to program the switching frequency from 100kHz to 1.3MHz for optimized efficiency, performance, and external component size. For an appropriate RSET resistor value see Table 1. An external resistor from the FSET pin to GND is required. Do not leave this pin open. For RT8541 the switching frequency is fixed and set at 650kHz typically. Table 1. Switching Frequency vs. RSET Value (1% Resistors) RSET (k) Frequency (kHz) 15 1300 20 1000 25 840 30 720 32 650 40 556 Inductor Selection 50 456 The inductance depends on the maximum input current. As a general rule, the inductor ripple current range is 20% to 40% of the maximum input current. If 40% is selected as an example, the inductor current can be calculated according to the following equation : 60 360 IIN(MAX) = VOUT IAPD VIN Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A Output Capacitor Selection The output ripple voltage is an important index for estimating chip performance. This portion consists of two parts. One is the product of the inductor current with the ESR of the output capacitor, while the other part is formed by the charging and discharging process of the output capacitor. As shown in Figure 1, ΔVOUT2 can be evaluated based on the ideal energy equalization. According to the definition of Q, the Q value can be calculated as the following equation : Q = 1 IIN 1 IL IAPD IIN 1 IL IAPD 2 2 2 VIN 1 = COUT VOUT2 VOUT2 fSET where fSET is the switching frequency, and ΔIL is the inductor ripple current. Bring COUT to the left side to estimate the value of ΔVOUT2 according to the following equation : D IAPD VOUT2 = COUT fSET where D is the duty cycle and η is the Boost converter efficiency. Finally, taking ESR into account, the overall output ripple voltage can be determined by the following equation : D IOUT VOUT = IIN ESR COUT fOSC For applications with out voltage less than 45V, intermediate output pin VOUT1 can directly serve as the output pin. Typically use a 2μF capacitor for output voltage less than 25V and 1μF capacitor for output voltage between 25V and 45V. When output voltage goes beyond 45V, a charge pump must be formed with cascaded 0.47μF capacitors C1 and C2 at the output nodes. A typical 0.1μF capacitor is used as the flying capacitor CFLY to form the charge pump. Always use a capacitor with sufficient voltage rating. Either ceramic or solid tantalum capacitors may be used for the input decoupling capacitor, which should be placed as close as possible to the RT8541. A 1μF capacitor is sufficient for most applications. Input Capacitor Selection Low ESR ceramic capacitors are recommended for input capacitor applications. Low ESR will effectively reduce the input voltage ripple caused by switching operation. A 10μF capacitor is sufficient for most applications. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8541/A-01 June 2015 Nevertheless, this value can be decreased for lower output current requirement. Another consideration is the voltage rating of the input capacitor which must be greater than the maximum input voltage. APD Current Monitor The power supply switching noise associated with a switching power supply can interfere with the photodiode DC measurement. To suppress this noise, a 0.1μF capacitor is recommended at APD pin. An additional output low-pass filter, a 10k resistor and a 10nF capacitor in parallel at MON pin might limit the measurement accuracy of low level signals. For applications requiring fast current monitor response time, a RC low-pass filter at MONIN pin is used to replace the 0.1μF capacitor at APD pin to reduce the power supply noise and other wide band noise. APD Short Current Protection In some applications, a long cable or wire is used to connect the RT8541/A to APD. When APD is shorted to GND, APD pin voltage might ring below ground and damage the internal circuitry. To prevent damage from short-circuit event, a 100Ω resistor must be added between MONIN and VOUT2 pins. The APD short current is 200mV/R6. For a typical 2mA short current protection of APD, the R6 should be set at 100Ω. Thermal Considerations For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For WQFN-16L 3x3 package, the thermal resistance, θJA, is 30°C/W on a standard JEDEC 51-7 four-layer thermal test is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8541/A board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : Layout Considerations PCB layout is very important for designing switching power converter circuits. The following layout guides should be strictly followed for best performance of the RT8541/A. P D(MAX) = (125°C − 25°C) / (30°C/W) = 3.33W for WQFN-16L 3x3 package Maximum Power Dissipation (W)1 The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 2 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Place L and C1 as close as possible to the SW and PUMP pin. The trace should be as short and wide as possible. The compensation circuit should be kept away from the power loops and should be shielded with a ground trace to prevent any noise coupling. Place the compensation components as close as possible to VC pin. The exposed pad of the chip should be connected to ground plane for thermal consideration. 3.5 Four-Layer PCB 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 25 50 75 100 125 Ambient Temperature (°C) C4 R1 R4 VC APD MONIN VOUT2 CFB R2 R6 C2 GND C3 Place these Components as close as possible 16 15 14 13 1 12 2 11 GND 3 10 17 4 9 5 6 7 SHDN VIN GND GND C1 R5 Schottky diode must be located close to SW and GND pins as much as possible. 8 VOUT1 PUMP SW SW FB To MCU MON FSET FB CTRL Locate the Compensation components to VC pin as close as possible RSET GND To MCU Figure 2. Derating Curve of Maximum Power Dissipation CIN Input capacitor must be Placed as close to the IC as possible. L VIN Figure 3. PCB Layout Guide Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 is a registered trademark of Richtek Technology Corporation. DS8541/A-01 June 2015 RT8541/A Outline Dimension D SEE DETAIL A D2 L 1 E E2 e b A A1 1 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options A3 Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 2.950 3.050 0.116 0.120 D2 1.300 1.750 0.051 0.069 E 2.950 3.050 0.116 0.120 E2 1.300 1.750 0.051 0.069 e L 0.500 0.350 0.020 0.450 0.014 0.018 W-Type 16L QFN 3x3 Package Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. DS8541/A-01 June 2015 www.richtek.com 13