STLDC08 Step-up controller for LED supply Features ■ Input voltage range from 0.8 V to 3.6 V ■ Overvoltage protection ■ Drives N-channel MOSFET or NPN bipolar transistor ■ No control loop compensation required ■ FET driver for very precise PWM dimming DFN10 (3 x 3 mm) Applications ■ Single/dual cell NiMH, NiCd, or alkaline batteries ■ Small appliances LED lighting ■ Portable lighting Description The STLDC08 LED driver step-up controller is optimized to operate from one or two NiCd/NiMH or alkaline cells. The IC is able to drive an external MOSFET (N-channel) enabling it for use with wide power levels. Hysteretic control eliminates the need for small signal control loop compensation. The IC integrates an FET driver for a precise PWM dimming. STLDC08 comes in a DFN10 (3 x 3 mm) package. Table 1. Device summary Order code Marking Package STLDC08PUR STLDC08 DFN10 (3 x 3 mm.) February 2011 Doc ID 18476 Rev 1 1/29 www.st.com 29 Contents STLDC08 Contents 1 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8 7.1 Main control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.2 Start up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.3 Over voltage protection (OVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.4 Enable/PWM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.5 Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.1 LED current programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.2 Duty cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.3 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.4 Inductor peak current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.5 Power MOSFET selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.6 Schottky diode selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.7 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.8 Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 9 Demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 10 Layout suggestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2/29 Doc ID 18476 Rev 1 STLDC08 12 Contents Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Doc ID 18476 Rev 1 3/29 Application diagram STLDC08 1 Application diagram Figure 1. Electric schematic optimized for 2 LEDs and ILED = 200 mA L1 D1 RF BATTERY C1 C2 D3 M1 C3 Rs U1 4 7 EN/PWM 3 VCC DRV EN/PWM SENSE VOUT 2VCC PWMOUT C4 10 V5 FB GND EXP 8 11 C5 D2 9 6 C6 1 M2 2 5 Rfb AM07845v1 Table 2. List of components Reference Manufacturer Part number Value Size C1 Murata GRM21BR60J475 4.7 µF, 6.3 V 0805 C2 Murata GRM31CB31C106K 10 µF, 16 V 1206 C4 Murata GRM188R70J103KA01B 10 nF, 6.3 V 0603 C3, C5, C6 Murata GRM188R61C105K 1 µF, 16 V 0603 L Coilcraft LPS6235-103ML 10 µH 6 mm x 6 mm M1,M2 STMicroelectronics STS5DNF20V SO-8 D1 STMicroelectronics STPS2L30 SMA 4/29 Rfb 0.47 Ω 0805 Rs 0.047 Ω 0805 RF 0Ω 0603 Doc ID 18476 Rev 1 STLDC08 Application diagram Figure 2. Electric schematic optimized for 4 LEDs and ILED = 300 mA L1 D1 RF BATTERY C1 C2 D4 D5 D2 D3 M1 C3 Rs U1 4 7 EN/PWM 3 VCC DRV EN/PWM SENSE VOUT 2VCC PWMOUT C4 10 V5 FB GND C5 8 9 6 C6 1 2 M2 5 EXP 11 Rfb AM07892v1 Table 3. List of components Part reference Manufacturer Part number Value Size C1 Murata GRM21BR60J106KE19 10 µF, 6.3 V 0805 C2 Murata GRM31CR61C226K 22 µF, 16 V 1206 C4 Murata GRM188R70J103KA01B 10 nF, 6.3 V 0603 C3, C5, C6 Murata GRM188R61C105K 1 µF, 16 V 0603 M1,M2 STMicroelectronics STS5DNF20V SO-8 D1 STMicroelectronics STPS2L30 SMA L Coilcraft DO3316P-223_L 22 µH 12.95 mm x 9.4 mm Rfb 0.33 Ω 0805 Rs 0.033 Ω 0805 RF 0Ω 0603 Doc ID 18476 Rev 1 5/29 Absolute maximum ratings STLDC08 2 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol Parameter VCC Supply voltage Value Unit - 0.3 to 4.6 V EN/PWM Analog input - 0.3 to 7 V FB Analog input - 0.3 to 2 V SENSE Analog input - 0.3 to 20 V 2VCC Analog outputs 0 to 4 V V5 Analog outputs - 0.3 to 7 V DRV, PWMOUT Analog outputs VCC - 1.2 to 7 V VOUT Output voltage - 0.3 to 20 V ESD Human body model (all pins) ±2 kV PD DFN10L 3x3 TA = 25 °C 2.2 W TJ Junction temperature - 40 to 85 °C Storage temperature range - 55 to 85 °C TSTG Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Table 5. Thermal data Symbol RthJC RthJA Parameter Thermal resistance junction-case Thermal resistance junction-ambient 1. With two sides, two planes PCB following EIA/JEDEC JESD51-7 standard. 6/29 Doc ID 18476 Rev 1 Value Unit 3 °C/W 57.1 (1) °C/W STLDC08 Pin configuration 3 Pin configuration Figure 3. Pin connections (top through view) Bottom view Table 6. Top view Pin description Pin # Pin name 1 VOUT 2 PWMOUT 3 2Vcc Charge pump output 4 VCC Supply voltage when VOUT < 2 V, this pin represents the input of the internal charge pump 5 FB 6 SENSE 7 EN/PWM 8 GND Ground reference 9 DRV Driver output for Boost stage MOSFET 10 V5 Exposed Pad Pin function Over voltage protection and supply pin for the IC when VOUT > 2 V Driver of the external MOSFET for PWM dimming. The driver stage is controlled by EN/PWM signal Feedback pin for LED current control Sense resistor for current mode control and peak current limit Enable pin and PWM control input for PWMOUT pin Internal regulator output. Decouple this pin locally to the IC ground with a minimum of 1 µF ceramic capacitor The exposed pad needs to be connected and soldered to analog ground Doc ID 18476 Rev 1 7/29 Electrical characteristics 4 STLDC08 Electrical characteristics TA = -40 to 85; CIN = 22 µF; COUT =10 µF; PWMOUT = 3300 pF; DVR = 3300 pF; 2VCC =10 nF; V5 =1 µF; VCC = 1.5V; VOUT = 3 V; FB = GND; SENSE = GND; EN/PWM = VCC; unless otherwise specified. Table 7. Electrical characteristics Symbol Parameter Test conditions Min. Typ. Max. Unit 3.6 V General section VCC IVCC OVP IVOUT 2VCC Supply voltage range VOUT = GND 0.8 Supply current measured on VCC VOUT = GND pin with charge pump ON 3 Shutdown current EN = GND Shutdown mode 5 Overvoltage protection Rising edge Operating supply current measured on VOUT pin 18 mA 10 µA 19.5 V 100 µA VOUT = 3 V, FB = 500 mV (no switching) 60 VOUT = 3 V, FB = GND (switching) 800 VOUT = 10 V, FB = GND (switching) 1.3 2 mA 5 10 µA Shutdown current EN = GND Charge pump ON VOUT floating; VCC = 0.8 V 1.5 µA V Driver section (DRV output) VDRVL Low level voltage IDRV = 100 mA 80 160 mV VDRVH High level voltage IDRV = -100 mA 120 240 mV tR Rise time CDRV = 3300 pF 30 ns tF Fall time CDRV = 3300 pF 20 ns VFB Feedback voltage TA = 25 °C IFB Bias current FB = 2 V FB 90 105 116 mV 20 500 nA Timing TOFF(MIN) Minimum Off time 1 µs TON(MAX) Maximum On time 20 µs PWM OUT section VPWMOUTL Low level voltage IPWMOUT = 100 mA 200 400 mV VPWMOUTH High level voltage IPWMOUT = - 100 mA 250 500 mV 8/29 tr Rise time CPWMOUT = 3300 pF 30 ns tf Fall time CPWMOUT = 3300 pF 20 ns Doc ID 18476 Rev 1 STLDC08 Table 7. Electrical characteristics Electrical characteristics (continued) Symbol Parameter Test conditions Min. Typ. Max. Unit 70 100 130 mV 10 20 µA SENSE VSENSE MAX ISENSE Maximum current sense threshold Bias current VSENSE = 20 V EN/PWM section VIL Low level threshold VCC = 0.8 V 0.3 V VIL Low level threshold VCC = 3.6 V 0.4 V VIH High level threshold VCC = 0.8 V 0.8 V VIH High level threshold VCC = 3.6 V 1.2 V IEN/PWM EN/PWM pin current EN/PWM = 3.6 V 2 µA IEN/PWM EN/PWM pin current EN/PWM = 5 V 5 µA + 5 V regulator V5 Output voltage ΔV5/ΔVOUT Line regulation ΔV5 Load regulation VDROPOUT Dropout voltage ICC Short circuit current VOUT = 6 V; I5 = 10 mA 4.8 6 V < VOUT < 18 V; I5 = 10 mA 5 5.2 V 0.02 %/V 0.01 %/mA I5 = 10 mA 20 mV VOUT = 18 V; V5 = 0 V 140 mA 0 < I5 < 10 mA VOUT = 18 V Doc ID 18476 Rev 1 0.02 9/29 Typical performance characteristics STLDC08 5 Typical performance characteristics Figure 4. VFB vs. temperature Figure 5. !-V Maximum VSENSE vs. temperature !-V 63%.3% ;M6= 6&" ;M6= 6 /54 6 6 /54 6 Figure 6. IOUT vs. temperature FB = 0.5 V Figure 7. !-V IOUT vs. temperature FB = GND !-V ) 6/54 ;M!= )6/54 ;!= 6 /54 6&"6 6 /54 6&"'.$ Figure 8. 4EMPERATURE; #= 4EMPERATURE; #= Efficiency vs. input voltage 2 LEDs Figure 9. !-V Efficiency vs. input voltage 4 LEDs !-V %FF ;= %FF ;= ),%$ M!,%$S ),%$ M!,%$S 6## ;6= 10/29 4EMPERATURE; #= 4EMPERATURE ; #= 6## ;6= Doc ID 18476 Rev 1 STLDC08 Typical performance characteristics Figure 10. Startup timing and dimming ILED vs. time, 2 LEDs Figure 11. Dimming EN/PWM = 200 Hz, 2 LEDs VCC = 1.5 V; ILED = 200 mA 2LEDs VCC = 1.5 V; ILED = 200 mA 2LEDs Figure 12. Startup timing and dimming ILED vs. time, 4 LEDs Figure 13. Dimming EN/PWM = 200 Hz, 4 LEDs VCC = 3.6 V; ILED = 300 mA 4LEDs VCC = 3.6 V; ILED = 300 mA 4LEDs Figure 14. VCC = 1.5 V; ILED = 200 mA, 2LEDs Figure 15. VCC = 3.6 V; ILED = 300 mA, 4LEDs Doc ID 18476 Rev 1 11/29 Block diagram 6 STLDC08 Block diagram Figure 16. Block diagram VOUT Vcc Over Voltage Protection + - VOUT OVP TH +5 V LDO Charge Pump +5 V 2Vcc 2Vcc TOFF timer TOFF = 1 µsec S DRV DRIVER Q R GND TONMAX = 20 µsec Peak Current Comparator SENSE + OCP - RESET OCP_TH Sensed Current Ramp OCP_TH Peak Current Control FB - FB Feedback + 100 mV Comparator EN/PWM PWMOUT DRIVER AM07846v1 12/29 Doc ID 18476 Rev 1 STLDC08 Detailed description 7 Detailed description 7.1 Main control loop The STLDC08 is an LED driver step-up controller dedicated to handheld equipment, having a typical voltage ranging from 0.8 V to 1.5 V. The controller drives an N-channel Power MOSFET and implements a hysteretic current mode control with constant OFF time. Hysteretic operation eliminates the need for small signal control loop compensation. The control loop adapts the value of the inductor peak current as needed to deliver the desired current on the LED branch. The LED current is set by an external sense resistor RFB inserted between the feedback pin (FB) and GND. When the current mode control system operates in continuous mode the control peak current is almost equivalent to the average current control. 7.2 Start up At the startup phase, when the device is connected to the battery or when the EN pin is pulled high, the internal 2x charge pump starts to work, boosting the voltage on the 2VCC pin. When the 2VCC pin reaches 1.7 V a soft-start cycle begins. The external main MOSFET is switched on/off allowing the charging of the output capacitor. If the optional PWMOUT MOSFET is used for the dimming operation, the PWMOUT pin is held low, further assuring that no current is flowing. The PWMOUT pin starts to follow the PWM input when the soft-start cycle is ended. When VOUT voltage exceeds 1.9 V, the chip starts drawing its supply current from VOUT rather than from VCC, the charge pump is turned off and the voltage on the 2VCC pin goes to zero. When VOUT exceeds the forward voltage of LED VLED, the current starts flowing trough the LED, but, at this point, the voltage on the DRV pin is high enough to allow the main MOSFET to carry the necessary current. Doc ID 18476 Rev 1 13/29 Detailed description STLDC08 Figure 17. Timing diagram VCC 1.7 V 2VCC 1.9 V VOUT DRV VOUT >1.9 V STLDC08 is supplied by VOUT ICC VOUT > VLED, the current starts flowing through the LEDs ILED Follows EN/PWM input Soft start cycle ended, PWMOUT is realeased PWMOUT Charge Pump active 7.3 STLDC08 supplied by VOUT AM07847v1 Over voltage protection (OVP) As with any current source, the output voltage rises when the output gets high impedance or is disconnected. To prevent the output voltage exceeding the maximum switch voltage rating of the main switch, an overvoltage protection circuit is integrated. As soon as the output voltage exceeds the OVP threshold, the converter stops switching and the output voltage drops. When the output voltage falls below the OVP threshold, the converter continues operation until the output voltage exceeds the OVP threshold again. 7.4 Enable/PWM The enable pin allows disabling and enabling of the device as well as brightness control of the LEDs by applying a PWM signal. In order to avoid visible flicker, the frequency of the PWM signal should be higher than 120 Hz. Changing the PWM duty cycle therefore changes the LED brightness. 14/29 Doc ID 18476 Rev 1 STLDC08 7.5 Detailed description Dimming When PWMOUT goes to zero, the LED current immediately goes to zero and the energy stored in the coil is discharged on the output capacitor, causing an increase in the output voltage. As soon as the PWM goes back to high value, there is a big spike current on the LED. This could damage the LED itself. To avoid this, as soon as the input PWM signal goes to zero the controller immediately turns off the main switch (in order to discharge the coil current on the LED branch). In this way the PWM power is turned off with a delay in order to guarantee that FB goes high after PowerMOS turn off. After this delay, the flip-flop is ready to be set and the PWM power is turned off. In this condition the output voltage is slightly lower than the regulated value, but a current spike on the LED is avoided. Doc ID 18476 Rev 1 15/29 Application information STLDC08 8 Application information 8.1 LED current programming The LED current is set by an external resistor connected between the FB pin and GND. The following equation can be used to calculate the value of the RFB resistor which guarantees the desired output current: Equation 1 RFB = 0.1 ILED The feedback signal VFB is compared with the internal precision 100 mV voltage reference by the error amplifier. The internal reference has a guaranteed tolerance of 10 %. Tolerance of the sense resistor adds additional error to the output voltage. 1 % resistors are recommended. 8.2 Duty cycle The controlled off-time architecture is a hysteretic mode control. Hysteretic operation eliminates the need for small signal control loop compensation. When the converter runs in continuous conduction mode (CCM) the controller adapts the TON time in order to obtain the duty cycle given by the following relationship: Equation 2 D = 1− VIN VOUT + VD where VO is the output voltage given by: Equation 3 VO = n × VF(LED) + VFB and VD is the forward voltage of the Schottky diode. 8.3 Inductor selection As the hysteretic control scheme is inherently stable, the inductor value does not affect the stability of the regulator. The switching frequency, peak inductor current, and allowable ripple of the output current determine the value of the inductor. LED manufacturers generally recommend a value for LED current ripple ranging from 5 % to 20 % of LED average current. 16/29 Doc ID 18476 Rev 1 STLDC08 Application information As a first approximation we choose the inductor ripple current, IL, equal to approximately 40 % of the output current. Higher ripple current allows for smaller inductors, but it also increases the output capacitance for a given LED current ripple requirement. Conversely, lower ripple current can be obtained increasing the value of the inductance, and this enables a reduction of the output capacitor value. This trade-off can be altered once standard inductance and capacitance values are chosen. IL is determined by the input and output voltage, the value of the inductance, and TOFF. Figure 18. Timing diagram IPEAK IL IRIPPLE I IIN = OUT 1− D IOUT t TON TOFF AM07848v1 The minimum value of inductance which guarantees the fixed inductor ripple current can be determined using the following equation: Equation 4 L> (VOUT + Vd - VINMIN ) × TOFF (ΔIL ) where Vd is the forward drop of the Schottky diode, IL is the fixed inductor ripple current, and TOFF is the constant OFF time. The following equation shows the average inductor current as a function of the output current and duty cycle. Equation 5 I IL( AVG) = LED 1− D An inductor that can carry the maximum input DC current which occurs at the minimum input voltage should be chosen. The peak-to-peak ripple current is set by the inductance and a good starting point is to choose a ripple current of at least 40 % of its maximum value of the: Doc ID 18476 Rev 1 17/29 Application information STLDC08 Equation 6 ΔIL = 40% × IL( AVG) = 40% × ILED 1 − DMAX Where DMAX is given by: Equation 7 DMAX = 1 − VIN(MIN) VOUT + VD The value of the peak current on the inductor is given by the following equation: Equation 8 IL(PK ) = IL( AVG) + ΔIL 2 The minimum required saturation current of the inductor must be greater than IL(PK) and can be expressed as follows: Equation 9 IL(SAT ) > IL(PK ) = IOUT ΔI + L 1 − DMAX 2 The saturation current rating for the inductor should be checked at the maximum duty cycle and maximum output current. 8.4 Inductor peak current limit The value of the inductor peak current limit can be programmed either by using a sense resistor or by using the RDSON of the main Power MOSFET. The following equation gives the relationship between the peak current limit and the value of the sense resistor: Equation 10 IIN(MAX) = VSENSE 0.1 = RSENSE RSENSE The sense resistor value can be determined fixing the value of the inductor peak current limit equal to twice the value of the inductor peak current in steady-state conditions. 18/29 Doc ID 18476 Rev 1 STLDC08 Application information Equation 11 IIN(MAX) = 2 × IL(PK ) Equation 12 IL(PK ) = ΔI ILED + L 1 − DMAX 2 Equation 13 RSENSE = 0.1 2 × IL(PK ) If the RDS (ON) of the main Power MOSFET is used to sense the current on the inductor the following procedure must be performed to choose the Power MOSFET. During ON time, the SENSE comparator limits the voltage across the Power MOSFET to a nominal 100 mV. In that case, the maximum inductor current is given by the following relationships: Equation 14 IL(MAX) = VSENSE 100mV = RDS(ON) RDS(ON) Equation 15 IL(MAX) = 2 × IL(PK ) = 2 × ILED ΔI ⎞ ⎛ × ⎜1 + L ⎟⎟ 1 − DMAX ⎜⎝ 2 ⎠ Equation 16 RDS(ON) < 0.1× 8.5 1 − DMAX ΔI ⎞ ⎛ 2 × ILED × ⎜1 + L ⎟ 2 ⎠ ⎝ Power MOSFET selection A key parameter to take into account in the selection of the N-MOSFET is the maximum continuous drain current. As a safety design, it is important to choose a maximum continuous drain current equal to twice the maximum input current. Doc ID 18476 Rev 1 19/29 Application information STLDC08 Figure 19. Current diagram ON state L1 VBAT LX D1 COUT CIN LED DVR SENSE Rsense STLDC08 VOUT FB ON state RFB AM07849v1 Figure 20. Current diagram OFF state LX L1 VBAT D1 CIN COUT LED DVR SENSE Rsense STLDC08 VOUT FB OFF state RFB AM07850v1 Another important parameter is the drain source breakdown voltage. During the ON state, the potential of the LX point is 0 V, while during the OFF state the potential of this point rises to the output voltage plus the forward voltage of the D1. Therefore, the absolute VDS rating of the main switch must be greater than this voltage to prevent main switch damage. 20/29 Doc ID 18476 Rev 1 STLDC08 8.6 Application information Schottky diode selection Schottky diodes, with their low forward voltage and fast recovery time, are the ideal choice to maximize efficiency. The output diode in a boost converter conducts current only when the power switch is OFF. The average current is equal to the output current and the peak current is equal to the peak inductor current. Ensure that the diode's average and peak current ratings exceed the average and peak inductor current, respectively. In addition, the diode's reverse breakdown voltage must exceed the regulator output voltage. 8.7 Input capacitor The input capacitor of a boost converter is less critical than the output capacitor, due to the fact that the input current waveform is continuous. The input voltage source impedance determines the size of the input capacitor, which is typically in the range of 10 µF to 100 µF. A low ESR capacitor is recommended though it is not as critical as the output capacitor. 8.8 Output capacitor For best output voltage filtering, a low ESR output capacitor is recommended. Ceramic capacitors have a low ESR value but tantalum capacitors can be used as well, depending on the application. The output voltage ripple consists of two parts, the first is the product IL(PK) ESR, the second is caused by the charging and discharging process of the output capacitor. Equation 17 ΔVOUT = TON × ILED + ESR × IL(PK ) COUT where: IL(PK) = Peak current ILED = Load current COUT = Selected output capacitor ESR = Output capacitor ESR value Doc ID 18476 Rev 1 21/29 Demonstration board 9 STLDC08 Demonstration board Figure 21. Electrical schematic TP1 VIN J1 TP2 SW L1 1 TP3 VOUT D1 1 J3 1 1 2 1 2 RF POWER IN C1 TP5 LED C2 1 J2 TP4 1 2 DRV C3 M1 1 SENSE GND Rs U1 J4 4 1 2 3 7 3 EN/PWM VCC DRV EN/PWM SENSE VOUT 2VCC PWMOUT C4 10 V5 C5 GND 8 EXP FB 9 6 C6 1 2 M2 5 11 Rfb AM07900v1 Table 8. Bill of material optimized for 2 LEDs and ILED = 200 mA Reference Manufacturer Part number Value Size C1 Murata GRM21BR60J475 4.7 µF 6.3V 0805 C2 Murata GRM31CB31C106K 10 µF 16 V 1206 C4 Murata GRM188R70J103KA01B 10 nF, 6.3 V 0603 C3, C5, C6 Murata GRM188R61C105K 1 µF, 16 V 0603 L Coilcraft LPS6235-103ML 10µH 6 mm x 6 mm M1,M2 STMicroelectronics STS5DNF20V SO-8 D1 STMicroelectronics STPS2L30 SMA 22/29 Rfb 0.47 Ω 0805 Rs 0.047 Ω 0805 RF 0Ω Doc ID 18476 Rev 1 STLDC08 10 Layout suggestion Layout suggestion Figure 22. Assembly layer Figure 23. Top layer Doc ID 18476 Rev 1 23/29 Layout suggestion STLDC08 Figure 24. Bottom layer 24/29 Doc ID 18476 Rev 1 STLDC08 11 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. Doc ID 18476 Rev 1 25/29 Package mechanical data STLDC08 DFN10 (3x3 mm) mechanical data mm. mils. Dim. A Min. Typ. Max. Min. Typ. Max. 0.80 0.90 1.00 31.5 35.4 39.4 0.02 0.05 0.8 2.0 0.65 0.80 25.6 31.5 A1 A2 0.55 A3 21.7 0.20 7.9 b 0.18 0.25 0.30 7.1 9.8 11.8 D 2.85 3.00 3.15 112.2 118.1 124.0 D2 2.20 E 2.85 118.1 124.0 E2 1.40 e L ddd 86.6 3.00 3.15 112.2 1.75 55.1 0.50 0.30 0.40 68.9 19.7 0.50 0.08 11.8 15.7 19.7 3.1 7426335F 26/29 Doc ID 18476 Rev 1 STLDC08 Package mechanical data Tape & reel QFNxx/DFNxx (3x3) mechanical data mm. inch. Dim. Min. Typ. A Max. Min. Typ. 180 13.2 7.087 C 12.8 D 20.2 0.795 N 60 2.362 T 0.504 0.519 14.4 0.567 Ao 3.3 0.130 Bo 3.3 0.130 Ko 1.1 0.043 Po 4 0.157 P 8 0.315 Doc ID 18476 Rev 1 Max. 27/29 Revision history STLDC08 12 Revision history Table 9. Document revision history Date Revision 22-Feb-2011 1 28/29 Changes First release. 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