LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 LM3502 Step-Up Converter for White LED Applications Check for Samples: LM3502 FEATURES APPLICATIONS • • • 1 2 • • • • • • • • Drive up to 4, 6, 8 or 10 White LEDs for Dual Display Backlighting >80% Efficiency Output Voltage Options: 16V , 25V , 35V, and 44V Input Under-Voltage Protection Internal Soft Start Eliminating Inrush Current 1 MHz Constant Switching Frequency Wide Input Voltage: 2.5V to 5.5V Small External Components Low Profile Packages: <1 mm Height – 10 Bump DSBGA – 16 Pin WQFN Dual Display Backlighting in Portable Devices Cellular Phones and PDAs DESCRIPTION The LM3502 is a white LED driver for lighting applications. For dual display or large single white LED string backlighting applications, the LM3502 provides a complete solution. The LM3502 contains two internal white LED current bypass FET(Field Effect Transistor) switches that are ideal for controlling dual display applications. The white LED current can be adjusted with a PWM signal directly from a microcontroller without the need of an RC filter network. Typical Application L 22 PH D MAIN: 2 to 5 LEDs Sw + VSUPPLY CIN 4.7 PF VOUT1 VIN VOUT2 Cntrl COUT - LM3502-44 En1 1 PF Fb En2 AGND PGND SUB: 2 to 5 LEDs Logic Voltage Signal Inputs R1 Figure 1. Blacklight Configuration with 10 White LEDs 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2005–2013, Texas Instruments Incorporated LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com DESCRIPTION (CONTINUED) With no external compensation, cycle-by-cycle current limit, over-voltage protection, and under-voltage protection, the LM3502 offers superior performance over other application specific standard product step-up white LED drivers. Connection Diagrams A2 A1 4 3 2 1 A3 B1 B3 C1 C3 D1 D3 5 16 6 15 7 14 8 13 9 10 11 12 D2 Figure 2. TOP VIEW 10-Bump Thin DSBGA See Package Number (YPA0010) Figure 3. TOP VIEW 16-Lead Thin WQFN See Package Number (RGH0016A) PIN DESCRIPTIONS Bump # Pin # Name Description A1 9 Cntrl Shutdown Control Connection B1 7 Fb Feedback Voltage Connection C1 6 VOUT2 Drain Connections of The NMOS and PMOS Field Effect Transistor (FET) Switches (Figure 4: N2 and P1) D1 4 VOUT1 Over-Voltage Protection (OVP) and Source Connection of The PMOS FET Switch (Figure 4: P1) D2 2 and 3 Sw D3 15 and 16 PGND Power Ground Connection C3 14 AGND Analog Ground Connection B3 13 VIN Supply or Input Voltage Connection A3 12 En2 NMOS FET Switch Control Connection A2 10 En1 PMOS FET Switch Control Connection 1 NC No Connection 5 NC No Connection Drain Connection of The Power NMOS Switch (Figure 4: N1) 8 NC No Connection 11 NC No Connection DAP DAP Die Attach Pad (DAP), must be soldered to the printed circuit board’s ground plane for enhanced thermal dissipation. Cntrl (Bump A1): Shutdown control pin When VCntrl is ≥ 1.4V, the LM3502 is enabled or ON. When VCntrl is ≤ 0.3V, the LM3502 will enter into shutdown mode operation. The LM3502 has an internal pull down resistor on the Cntrl pin, thus the device is normally in the off state or shutdown mode of operation. Fb (Bump B1): Output voltage feedback connection The white LED string network current is set/programmed using a resistor from this pin to ground. VOUT2 (Bump C1): Drain connections of the internal PMOS and NMOS FET switches . (Figure 4: P1 and N2). It is recommended to connect 100nF at VOUT2 for the LM3502-35V 2 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 and LM3502-44 versions if VOUT2 is not used. VOUT1 (Bump D1): Source connection of the internal PMOS FET switch (Figure 4: P1) and OVP sensing node The output capacitor must be connected as close to the device as possible, between the VOUT1 pin and ground plane. Also connect the Schottky diode as close as possible to the VOUT1 pin to minimize trace resistance and EMI radiation. Sw (Bump D2): Drain connection of the internal power NMOS FET switch (Figure 4: N1) Minimize the metal trace length and maximize the metal trace width connected to this pin to reduce EMI radiation and trace resistance. PGND (Bump D3): Power ground pin Connect directly to the ground plane. AGND (Bump C3): Analog ground pin Connect the analog ground pin directly to the PGND pin. VIN (Bump B3): Supply or input voltage connection pin The CIN capacitor should be as close to the device as possible, between the VIN pin and ground plane. En2 (Bump A3): Enable pin for the internal NMOS FET switch (Figure 4: N2) during device operation When VEn2 is ≤ 0.3V, the internal NMOS FET switch turns on and the SUB display turns off. When VEn2 is ≥ 1.4V, the internal NMOS FET switch turns off and the SUB display turns on. The En2 pin has an internal pull down resistor, thus the internal NMOS FET switch is normally in the on state of operation with the SUB display turned off. If VEn1 and VEn2 are ≤ 0.3V and VCntrl is ≥ 1.4V, the LM3502 will enter a low IQ shutdown mode of operation where all the internal FET switches are off. If VOUT2 is not used, En2 must be grounded or floating and use En1 along with Cntrl, to enable the device. En1 (Bump A2): Enable pin for the internal PMOS FET switch (Figure 4: P1) during device operation When VEn1 is ≤ 0.3V, the internal PMOS FET switch turns on and the MAIN display is turned off. When VEn1 is ≥ 1.4V, the internal PMOS FET switch turns off and the MAIN display is turned on. The En1 pin has an internal pull down resistor, thus the internal PMOS FET switch is normally in the on state of operation with the MAIN display turned off. If VEn1 and VEn2 are ≤ 0.3V and VCntrl is ≥ 1.4V, the LM3502 will enter a low IQ shutdown mode of operation where all the internal FET switches are off. If VOUT2 is not used, En2 must be grounded and use En1 a long with Cntrl, to enable the device. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 3 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 Absolute Maximum Ratings www.ti.com (1) (2) (3) −0.3V to +5.5V VIN Pin Sw Pin −0.3V to +48V Fb Pin −0.3V to +5.5V Cntrl Pin −0.3V to +5.5V VOUT1 Pin −0.3V to +48V VOUT2 Pin −0.3V to VOUT1 En1 −0.3V to +5.5V −0.3V to +5.5V En2 Continuous Power Dissipation Internally Limited Maximum Junction Temperature (TJ-MAX) +150°C −65°C to +150°C Storage Temperature Range ESD Rating (4) Human Body Model: Machine Model: (1) (2) (3) (4) 2 kV 200V All voltages are with respect to the potential at the GND pin. Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical characteristic specifications do not apply when operating the device outside of its rated operating conditions. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. Operating Conditions (1) (2) Junction Temperature (TJ) Range −40°C to +125°C Ambient Temperature (TA) Range −40°C to +85°C Input Voltage, VIN Pin 2.5V to 5.5V Cntrl, En1, and En2 Pins (1) (2) 0V to 5.5V Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical characteristic specifications do not apply when operating the device outside of its rated operating conditions. All voltages are with respect to the potential at the GND pin. Thermal Properties (1) Junction-to-Ambient Thermal Resistance (θJA) DSBGA Package 65°C/W WQFN Package 49°C/W (1) The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. See Thermal Properties for the thermal resistance. The maximum allowable power dissipation at any ambient temperature is calculated using: PD(MAX) = (TJ(MAX) – TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature. For more information on this topic, please refer toApplication Note 1187: Leadless Leadframe Package (LLP) and Application Note 1112 for DSBGA chip scale package. Preliminary Electrical Characteristics (1) (2) Limits in standard typeface are for TJ = 25°C. Limits in bold typeface apply over the full operating junction temperature range (−40°C ≤ TJ ≤ +125°C). Unless otherwise specified, VIN = 2.5V. Symbol Parameter VIN Input Voltage IQ Non-Switching Switching Shutdown Low IQ Shutdown VFb Feedback Voltage (1) (2) 4 Conditions Min Typ Max Units 5.5 V 0.5 1.9 0.1 6 1 3 3 15 mA mA µA µA 0.25 0.3 V 2.5 Fb > 0.25V Fb = 0V, Sw Is Floating Cntrl = 0V Cntrl = 1.5V, En1 = En2 = 0V 0.18 All voltages are with respect to the potential at the GND pin. Min and Max limits are ensured by design, test, or statistical analysis. Typical numbers are not ensured, but do represent the most likely norm. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 Preliminary Electrical Characteristics (1) (2) (continued) Limits in standard typeface are for TJ = 25°C. Limits in bold typeface apply over the full operating junction temperature range (−40°C ≤ TJ ≤ +125°C). Unless otherwise specified, VIN = 2.5V. Symbol Parameter Conditions Min Typ Max Units 250 400 450 450 400 600 750 750 650 800 1050 1050 mA 64 500 nA 1 1.2 MHz 0.55 1.1 Ω PMOS ON Resistance of IPMOS = 20 mA, En1 = 0V, En2 = 1.5V VOUT1/VOUT2 Switch (Figure 4: N1) 5 10 Ω NMOS ON Resistance of INMOS = 20 mA, En1 = 1.5V, En2 = 0V VOUT2/Fb Switch (Figure 4: N2) 2.5 5 Ω NMOS Power Switch Current Limit −16, −25, −35, −44, IFb Feedback Pin Bias Current (3) Fb = 0.25V FS Switching Frequency RDS(ON) NMOS Power Switch ON ISw = 500 mA Resistance (Figure 4: N1) ICL RPDS(ON) RNDS(ON) Fb Fb Fb Fb = 0V = 0V = 0V = 0V 0.8 DMAX Maximum Duty Cycle Fb = 0V ICntrl Cntrl Pin Input Bias Current (4) Cntrl = 2.5V Cntrl = 0V ISw Sw Pin Leakage Current Sw = 42V, Cntrl = 0V IVOUT1(OFF) VOUT1 Pin Leakage Current (5) VOUT1 = 14V, VOUT1 = 23V, VOUT1 = 32V, VOUT1 = 42V, Cntrl Cntrl Cntrl Cntrl VOUT1 Pin Bias Current VOUT1 = 14V, VOUT1 = 23V, VOUT1 = 32V, VOUT1 = 42V, Cntrl Cntrl Cntrl Cntrl 0.01 5 µA = 0V (16) = 0V (25) = 0V (35) = 0V (44) 0.1 0.1 0.1 0.1 3 3 3 3 µA = 1.5V = 1.5V = 1.5V = 1.5V 40 50 50 85 80 100 100 140 µA 0.1 3 µA 2.4 2.3 2.5 2.2 (16) (16) (25) (25) (35) (35) (44) (44) 14.5 14.0 22.5 21.5 32.0 31.0 40.5 39.0 15.5 15 24 23 34 33 42 41 16.5 16.0 25.5 24.5 35.0 34.0 43.5 42.0 PMOS FET Switch Enabling Threshold (Figure 4: P1) Off Threshold (Display Lighting) On Threshold (Display Lighting) 0.8 0.8 0.3 1.4 NMOS FET Switch Enabling Threshold (Figure 4: N2) Off Threshold (Display Lighting) On Threshold (Display Lighting) 0.8 0.8 0.3 1.4 Device Enabling Threshold Off Threshold OnThreshold 0.8 0.8 0.3 1.4 8 12 16 7 0.1 14 (5) (16) (25) (35) (44) VOUT2 Pin Leakage Current (5) Fb = 0V, Cntrl = 0V, VOUT2 = 42V UVP Under-Voltage Protection On Threshold Off Threshold Over-Voltage Protection On Threshold Off Threshold On Threshold Off Threshold On Threshold Off Threshold On Threshold Off Threshold VEn1 VEn2 VCntrl (6) TSHDW Shutdown Delay Time IEn1 En1 Pin Input Bias Current (3) (4) (5) (6) % 14 IVOUT2 OVP 95 7 0.1 (5) IVOUT1(ON) 90 En1 = 2.5V En1 = 0V µA V V V V V ms µA Current flows out of the pin. Current flows into the pin. Current flows into the pin. The on threshold indicates that the LM3502 is no longer switching or regulating LED current, while the off threshold indicates normal operation. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 5 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com Preliminary Electrical Characteristics (1) (2) (continued) Limits in standard typeface are for TJ = 25°C. Limits in bold typeface apply over the full operating junction temperature range (−40°C ≤ TJ ≤ +125°C). Unless otherwise specified, VIN = 2.5V. Symbol IEn2 Parameter Conditions En2 Pin Input Bias Current Min Typ Max 7 0.1 14 En2 = 2.5V En2 = 0V Units µA BLOCK DIAGRAM 13 VIN Sw 2,3 Soft Start Thermal Shutdown OVP Comparator Current Limit UVP Comparator - UVP Reference Error Amplifier Fb 4 OVP Reference + Light Load Reference VOUT1 + - + - Light Load Comparator Current Sense PWM Comparator + P1 N1 Driver Logic + Fb Reference VOUT2 N2 6 Oscillator FET Logic + - Duty Limit Comparator Shutdown Comparator Duty Limit Reference 7 14 9 AGND Cntrl 15,16 PGND 10 12 En2 Fb En1 Figure 4. Block Diagram Detailed Description of Operation The LM3502 utilizes an asynchronous current mode pulse-width-modulation (PWM) control scheme to regulate the feedback voltage over specified load conditions. The DC/DC converter behaves as a controlled current source for white LED applications. The operation can best be understood by referring to the block diagram in Figure 4 for the following operational explanation. At the start of each cycle, the oscillator sets the driver logic and turns on the internal NMOS power device, N1, conducting current through the inductor and reverse biasing the external diode. The white LED current is supplied by the output capacitor when the internal NMOS power device, N1, is turned on. The sum of the error amplifier’s output voltage and an internal voltage ramp are compared with the sensed power NMOS, N1, switch voltage. Once these voltages are equal, the PWM 6 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 comparator will then reset the driver logic, thus turning off the internal NMOS power device, N1, and forward biasing the external diode. The inductor current then flows through the diode to the white LED load and output capacitor. The inductor current recharges the output capacitor and supplies the current for the white LED load. The oscillator then resets the driver logic again repeating the process. The output voltage of the error amplifier controls the current through the inductor. This voltage will increase for larger loads and decrease for smaller loads limiting the peak current in the inductor and minimizing EMI radiation. The duty limit comparator is always operational, it prevents the internal NMOS power switch, N1, from being on for more than one oscillator cycle and conducting large amounts of current. The light load comparator allows the LM3502 to properly regulate light/small white LED load currents, where regulation becomes difficult for the LM3502’s primary control loop. Under light load conditions, the LM3502 will enter into a pulse skipping pulse-frequency-mode (PFM) of operation where the switching frequency will vary with the load. The LM3502 has 2 control pins, En1 and En2, used for selecting which segment of a single white LED string network is active for dual display applications. En1 controls the main display (MAIN) segment of the single string white LED network between pins VOUT1 and VOUT2. En2 controls the sub display (SUB) segment of the single string white LED network between the VOUT2 and Fb. For a quick review of the LM3502 control pin operational characteristics, see Figure 5. When the Cntrl pin is ≥ 1.4V, the LM3502 will enter in low IQ state if both En1 and En2 ≤ 0.3V. At this time, both the P1 and N2 FETs will turn off. The output voltage will be a diode drop below the supply voltage and the softstart will be reset limiting the peak inductor current at the next start-up. The LM3502 is designed to control the LED current with a PWM signal without the use of an external RC filter. Utilizing special circuitry, the LM3502 can operate over a large range of PWM frequencies without restarting the soft-start allowing for fast recovery at high PWM frequencies. Figure 6 represents a PWM signal driving the Cntrl pin where tL is defined as the low time of the signal. The following is true: • If tL < 12ms (typical): The device will stop switching during this time and the soft-start will not be reset allowing LED current PWM control. • If tL > 12ms (typical): The device will shutdown and the soft-start will reset to prevent high peak currents at the next startup. Both the N2 and P1 switches will turn off. The LM3502 has dedicated protection circuitry active during normal operation to protect the integrated circuit (IC) and external components. The thermal shutdown circuitry turns off the internal NMOS power device, N1, when the internal semiconductor junction temperature reaches excessive levels. The LM3502 has a under-voltage protection (UVP) comparator that disables the internal NMOS power device when battery voltages are too low, thus preventing an on state where the internal NMOS power device conducts large amounts of current. The overvoltage protection (OVP) comparator prevents the output voltage from increasing beyond the protection limit when the white LED string network is removed or if there is a white LED failure. OVP allows for the use of low profile ceramic capacitors at the output. The current though the internal NMOS power device, N1, is monitored to prevent peak inductor currents from damaging the IC. If during a cycle (cycle=1/switching frequency) the peak inductor current exceeds the current limit for the LM3502, the internal NMOS power device will be turned off for the remaining duration of that cycle. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 7 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com Shutdown Cntrl* En1 En2 Result* (See Figure 1 and Figure 2) Shutdown 1.4V 0.3V 0.3V [P1ÆOFF N2ÆOFF N1ÆOFF] or [MAINÆOFF SUBÆOFF N1ÆOFF] 1.4V 1.4V 0.3V [P1ÆOFF N2ÆON N1ÆSwitching] or [MAINÆON SUBÆOFF N1ÆSwitching] 1.4V 0.3V 1.4V [P1ÆON N2ÆOFF N1ÆSwitching] or [MAINÆOFF SUBÆON N1ÆSwitching] 1.4V 1.4V 1.4V [P1ÆOFF N2ÆOFF N1ÆSwitching] or [MAINÆON SUBÆON N1ÆSwitching] 0.3V 0.3V 0.3V [P1ÆOFF N2ÆOFF N1ÆOFF] or [MAINÆOFF SUBÆOFF N1ÆOFF] X 0.3V 1.4V 0.3V [P1ÆOFF N2ÆOFF N1ÆOFF] or [MAINÆOFF SUBÆOFF N1ÆOFF] X 0.3V 0.3V 1.4V [P1ÆOFF N2ÆOFF N1ÆOFF] or [MAINÆOFF SUBÆOFF N1ÆOFF] X 0.3V 1.4V 1.4V [P1ÆOFF N2ÆOFF N1ÆOFF] or [MAINÆOFF SUBÆOFF N1ÆOFF] X Low IQ X *Table is only valid for when the Cntrl pin signal is a non-periodic logic signal, not a PWM signal. Figure 5. Operational Characteristics Table 1.4V Cntrl 0.3V tL (Typ) Figure 6. Control Signal Waveform 8 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 Typical Performance Characteristics ( Circuit in Figure 1: L = DO1608C-223 and D = MBRM140T3. Efficiency: η = POUT/PIN = [(VOUT – VFb) * IOUT]/[VIN * IIN]. TA= 25°C, unless otherwise stated.) Switching Frequency vs Temperature 0.600 1.03 0.580 1.02 -40oC 0.560 0.540 25oC 0.520 125oC 0.500 0.480 0.460 1.00 0.99 0.98 0.97 0.96 0.440 0.95 0.420 0.94 0.400 2.5 3.0 3.5 4.0 VIN = 2.5V 1.01 FREQUENCY (MHz) NON-SWITCHING IQ (mA) IQ (Non-Switching) vs VIN 4.5 5.0 0.93 -40 -20 0 20 40 60 80 100 120 -30 -10 10 30 50 70 90 110 130 5.5 INPUT VOLTAGE (V) TEMPERATURE (oC) Figure 7. Figure 8. IQ (Switching) vs VIN IQ (Switching) vs Temperature 1.95 4.00 VIN = 2.5V SWITCHING IQ (mA) SWITCHING IQ (mA) 3.50 -40oC 3.00 125oC 25oC 2.50 1.90 1.85 1.80 2.00 1.50 2.5 3.0 3.5 4.0 4.5 5.0 1.75 -40 -20 0 20 40 60 80 100 120 -30 -10 10 30 50 70 90 110 130 5.5 INPUT VOLTAGE (V) TEMPERATURE (oC) Figure 9. Figure 10. 10 LED Efficiency vs LED Current 8 LED Efficiency vs LED Current 90 90 VIN = 5.5V 85 70 VIN = 3.3V 65 60 VIN = 2.7V VIN = 3V 55 70 50 40 2.5 40 32 42 52 VIN = 2.7V 60 55 45 22 VIN = 3V 65 50 12 VIN = 3.3V 75 45 2 VIN = 4.2V VIN = 5.5V 80 VIN = 4.2V 75 EFFICIENCY (%) EFFICIENCY (%) 80 85 62 5.0 LED CURRENT (mA) 7.5 12.5 17.5 22.5 27.5 32.5 10.0 15.0 20.0 25.0 30.0 35.0 LED CURRENT (mA) Figure 11. Figure 12. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 9 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) ( Circuit in Figure 1: L = DO1608C-223 and D = MBRM140T3. Efficiency: η = POUT/PIN = [(VOUT – VFb) * IOUT]/[VIN * IIN]. TA= 25°C, unless otherwise stated.) 6 LED Efficiency vs LED Current 95 95 VIN = 5.5V VIN = 5.5V 90 85 EFFICIENCY (%) EFFICIENCY (%) 90 80 VIN = 4.2V VIN = 3.3V 75 VIN = 3V 70 4 LED Efficiency vs LED Current VIN = 2.7V 85 VIN = 4.2V 80 VIN = 2.7V 75 VIN = 3.3V 65 60 70 2 12 22 32 42 52 62 72 82 2 10 18 LED CURRENT (mA) Figure 13. Figure 14. Cntrl Pin Current vs Cntrl Pin Voltage Maximum Duty Cycle vs Temperature 98 25 VIN = 2.5 MAX DUTY CYCLE (%) CNTRL PIN CURRENT (PA) 30 -40oC 20 15 25oC 10 125oC 97 96 95 5 0 0.0 1.0 2.0 3.0 4.0 94 -40 -20 0 20 40 60 80 100 120 -30 -10 10 30 50 70 90 110 130 5.0 CNTRL PIN VOLTAGE (V) TEMPERATURE (oC) Figure 15. Figure 16. En1 Pin Current vs En1 Pin Voltage En2 Pin Current vs En2 Pin Voltage 25 30 20 EN2 PIN CURRENT (PA) EN1 PIN CURRENT (PA) 25 -40oC 15 o 25 C 10 o 125 C 5 0 0.0 1.0 2.0 3.0 4.0 20 15 -40oC 10 25oC 125oC 5 0 0.0 5.0 1.0 2.0 3.0 4.0 5.0 EN2 PIN VOLTAGE (V) EN1 PIN VOLTAGE (V) Figure 17. 10 26 34 42 50 58 66 74 LED CURRENT (mA) Figure 18. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 Typical Performance Characteristics (continued) ( Circuit in Figure 1: L = DO1608C-223 and D = MBRM140T3. Efficiency: η = POUT/PIN = [(VOUT – VFb) * IOUT]/[VIN * IIN]. TA= 25°C, unless otherwise stated.) VOUT1 Pin Current vs VOUT1 Pin Voltage 1000 INMOS = 400 mA 140 120 -40oC 100 25oC 80 60 900 POWER NMOS RDS(ON) (m:) VOUT1 PIN BIAS CURRENT (PA) 160 Power NMOS RDS(ON) (Figure 4: N1) vs VIN o 125 C 40 700 600 25oC 500 300 2.5 0 8 16 24 32 40 -40oC 400 20 0 125oC 800 48 3.0 3.5 VOUT1 PIN VOLTAGE (V) 3.50 4.0 4.5 5.5 Figure 19. Figure 20. NMOS RDS(ON) (Figure 4: N2) vs VIN PMOS RDS(ON) (Figure 4: P1) vs VIN 10 IPMOS = 20 mA INMOS = 20 mA 3.00 PMOS SWITCH RDS(ON) (:) NMOS SWITCH RDS(ON) (:) 5.0 INPUT VOLTAGE (V) 125oC 2.50 2.00 25oC 1.50 o -40 C 1.00 0.50 0.00 2.5 9 8 125oC 7 6 25oC 5 -40oC 4 3.0 3.5 4.0 4.5 5.0 3 2.0 5.5 12.0 22.0 32.0 42.0 VOUT1 PIN VOLTAGE (V) INPUT VOLTAGE (V) Figure 21. Figure 22. Feedback Voltage vs Temperature Current Limit (LM3502-16) vs VIN 480 -16 CURRENT LIMIT (mA) 460 440 T = 85oC 420 400 T = 25oC 380 360 T = -40oC 340 320 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 23. Figure 24. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 11 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) ( Circuit in Figure 1: L = DO1608C-223 and D = MBRM140T3. Efficiency: η = POUT/PIN = [(VOUT – VFb) * IOUT]/[VIN * IIN]. TA= 25°C, unless otherwise stated.) Current Limit (LM3502-16) vs Temperature 620 440 Current Limit (LM3502-25) vs VIN T = 85oC 600 -25 CURRENT LIMIT (mA) -16 CURRENT LIMIT (mA) 420 VIN = 2.5V 400 VIN = 5.5V 380 360 580 T = 25oC 560 540 520 500 T = -40oC 480 340 460 320 -40 -25 -10 5 20 35 50 65 440 2.5 80 o TEMPERATURE ( C) -25 CURRENT LIMIT (mA) 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 25. Figure 26. Current Limit (LM3502-25) vs Temperature Current Limit (LM3502-35/44) vs Temperature 780 770 VIN = 2.5V -35/44 CURRENT LIMIT (mA) 620 600 3.0 580 560 VIN = 5.5V 540 520 500 480 460 760 750 740 730 720 VIN = 2.5V 710 440 700 420 -40 -25 -10 690 -40 -25 -10 5 20 35 50 65 80 o 5 20 35 50 65 80 o TEMPERATURE ( C) TEMPERATURE ( C) Figure 27. Figure 28. 780 Current Limit (LM3502-35/44) vs VIN CURRENT LIMIT (mA) 770 760 85oC 750 740 25oC -40oC 730 720 710 700 690 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 29. 12 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 APPLICATION INFORMATION WHITE LED CURRENT SETTING The LED current is set using the following equation: VFb ILED = R1 where • • • ILED: White LED Current. VFb: Feedback Pin Voltage. VFb = 0.25V, Typical. R1: Current Setting Resistor. (1) WHITE LED DIMMING For dimming the white LED string with a pulse-width-modulated (PWM) signal on the Cntrl pin, care must taken to balance the tradeoffs between audible noise and white LED brightness control. For best PWM duty cycle vs. white LED current linearity, the PWM frequency should be between 200Hz and 500Hz. Other PWM frequencies can be used, but the linearity over input voltage and duty cycle variation will not be as good as what the 200Hz to 500Hz PWM frequency spectrum provides. To minimize audible noise interference, it is recommended that a output capacitor with minimal susceptibility to piezoelectric induced stresses be used for the particular applications that require minimal or no audible noise interference. PWM Signal VSUPPLY Sw VIN VOUT1 Cntrl VOUT2 Unconnected Floating LM3502 En1 GND Fb En2 AGND PGND R1 Figure 30. If VOUT2 is not used , En2 must be grounded Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 13 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com Inductor Current tON = DTS (Vin - Vout)/L Vin/L IL (avg) ' iL Time TS Figure 31. Inductor Current Waveform CONTINUOUS AND DISCONTINUOUS MODES OF OPERATION Since the LM3502 is a constant frequency pulse-width-modulated step-up regulator, care must be taken to make sure the maximum duty cycle specification is not violated. The duty cycle equation depends on which mode of operation the LM3502 is in. The two operational modes of the LM3502 are continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Continuous conduction mode refers to the mode of operation where during the switching cycle, the inductor current never goes to and stays at zero for any significant amount of time during the switching cycle. Discontinuous conduction mode refers to the mode of operation where during the switching cycle, the inductor current goes to and stays at zero for a significant amount of time during the switching cycle. Figure 31 illustrates the threshold between CCM and DCM operation. In Figure 31, the inductor current is right on the CCM/DCM operational threshold. Using this as a reference, a factor can be introduced to calculate when a particular application is in CCM or DCM operation. R is a CCM/DCM factor we can use to compute which mode of operation a particular application is in. If R is ≥ 1, then the application is operating in CCM. Conversely, if R is < 1, the application is operating in DCM. The R factor inequalities are a result of the components that make up the R factor. From Figure 31, the R factor is equal to the average inductor current, IL(avg), divided by half the inductor ripple current, ΔiL. Using Figure 31 the following equation can be used to compute R factor: 2 * IL (avg) R= 'iL [IOUT] IL (avg) = [(1-D) * Eff] [VIN * D] 'iL = [L * Fs] 2 [2 * IOUT * L * Fs * (VOUT) ] R= 2 [(VIN) * Eff * (VOUT - VIN)] where • • • • • • • • • VIN: Input Voltage. VOUT: Output Voltage. Eff: Efficiency of the LM3502. Fs: Switching Frequency. IOUT: White LED Current/Load Current. L: Inductance Magnitude/Inductor Value. D: Duty Cycle for CCM Operation. ΔiL: Inductor Ripple Current IL(avg): Average Inductor Current (2) For CCM operation, the duty cycle can be computed with: 14 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 tON D= TS [VOUT - VIN] D= [VOUT] where • • • D: Duty Cycle for CCM Operation. VOUT: Output Voltage. VIN: Input Voltage. (3) For DCM operation, the duty cycle can be computed with: tON D= TS [2 * IOUT * L * (VOUT - VIN) * Fs] D= 2 [(VIN) * Eff] where • • • • • • D: Duty Cycle for DCM Operation. VOUT: Output Voltage. VIN: Input Voltage. IOUT: White LED Current/Load Current. Fs: Switching Frequency. L: Inductor Value/Inductance Magnitude. (4) INDUCTOR SELECTION In order to maintain inductance, an inductor used with the LM3502 should have a saturation current rating larger than the peak inductor current of the particular application. Inductors with low DCR values contribute decreased power losses and increased efficiency. The peak inductor current can be computed for both modes of operation: CCM and DCM. The cycle-by-cycle peak inductor current for CCM operation can be computed with: 'iL IPeak | IL (avg) + 2 [VIN * D] [IOUT] + IPeak | [2 * L * Fs] [(1 - D) * Eff] where • • • • • • • • • VIN: Input Voltage. Eff: Efficiency of the LM3502. Fs: Switching Frequency. IOUT: White LED Current/Load Current. L: Inductance Magnitude/Inductor Value. D: Duty Cycle for CCM Operation. IPEAK: Peak Inductor Current. ΔiL: Inductor Ripple Current. IL(avg): Average Inductor Current. (5) The cycle-by-cycle peak inductor current for DCM operation can be computed with: [VIN * D] IPeak | [L * Fs] where • VIN: Input Voltage. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 15 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 • • • • www.ti.com Fs: Switching Frequency. L: Inductance Magnitude/Inductor Value. D: Duty Cycle for DCM Operation. IPEAK: Peak Inductor Current. (6) The minimum inductance magnitude/inductor value for the LM3502 can be calculated using the following, which is only valid when the duty cycle is > 0.5: [VIN * RDS(ON) * ((D/'¶) - 1)] L> [1.562 * Fs] where • • • • • D: Duty Cycle. D: 1–D. RDS(ON): NMOS Power Switch ON VIN: Input Voltage. L: Inductance Magnitude/Inductor Value. (7) This equation gives the value required to prevent subharmonic oscillations. The result of this equation and the inductor average and ripple current should be accounted for when choosing an inductor value. Some recommended inductor manufacturers included but are not limited to: CoilCraft DO1608C-223 DT1608C-223 www.coilcraft.com CAPACITOR SELECTION Multilayer ceramic capacitors are the best choice for use with the LM3502. Multilayer ceramic capacitors have the lowest equivalent series resistance (ESR). Applied voltage or DC bias, temperature, dielectric material type (X7R, X5R, Y5V, etc), and manufacturer component tolerance have an affect on the true or effective capacitance of a ceramic capacitor. Be aware of how your application will affect a particular ceramic capacitor by analyzing the aforementioned factors of your application. Before selecting a capacitor always consult the capacitor manufacturer’s data curves to verify the effective or true capacitance in your application. INPUT CAPACITOR SELECTION The input capacitor serves as an energy reservoir for the inductor. In addition to acting as an energy reservoir for the inductor the input capacitor is necessary for the reduction in input voltage ripple and noise experienced by the LM3502. The reduction in input voltage ripple and noise helps ensure the LM3502’s proper operation, and reduces the effect of the LM3502 on other devices sharing the same supply voltage. To ensure low input voltage ripple, the input capacitor must have an extremely low ESR. As a result of the low input voltage ripple requirement multilayer ceramic capacitors are the best choice. A minimum capacitance of 2.0 µF is required for normal operation, so consult the capacitor manufacturer’s data curves to verify whether the minimum capacitance requirement is going to be achieved for a particular application. OUTPUT CAPACITOR SELECTION The output capacitor serves as an energy reservoir for the white LED load when the internal power FET switch (Figure 4: N1) is on or conducting current. The requirements for the output capacitor must include worst case operation such as when the load opens up and the LM3502 operates in over-voltage protection (OVP) mode operation. A minimum capacitance of 0.5µF is required to ensure normal operation. Consult the capacitor manufacturer’s data curves to verify whether the minimum capacitance requirement is going to be achieved for a particular application. Some recommended capacitor manufacturers included but are not limited to: Taiyo Yuden GMK212BJ105MD (0805/35V) www.t-yuden.com muRata GRM40-035X7R105K (0805/50V) www.murata.com 16 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com TDK SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 C3216X7R1H105KT (1206/50V) www.tdktca.com C3216X7R1C475K (1206/16V) AVX 08053D105MAT (0805/25V) www.avxcorp.com 08056D475KAT (0805/6.3V) 1206ZD475MAT (1206/10V) DIODE SELECTION To maintain high efficiency it is recommended that the average current rating (IF or IO) of the selected diode should be larger than the peak inductor current (ILpeak). At the minimum, the average current rating of the diode should be larger than the maximum LED current. To maintain diode integrity the peak repetitive forward current (IFRM) must be greater than or equal to the peak inductor current (ILpeak). Diodes with low forward voltage ratings (VF) and low junction capacitance magnitudes (CJ or CT or CD) are conducive to high efficiency. The chosen diode must have a reverse breakdown voltage rating (VR and/or VRRM) that is larger than the output voltage (Vout). No matter what type of diode is chosen, Schottky or not, certain selection criteria must be followed: 1. VR and VRRM > VOUT 2. IF or IO ≥ ILOAD or IOUT 3. IFRM ≥ ILpeak Some recommended diode manufacturers included but are not limited to: Vishay SS12(1A/20V) www.vishay.com SS14(1A/40V) SS16(1A/60V) On Semiconductor MBRM120E (1A/20V) www.onsemi.com MBRS1540T3 (1.5A/40V) MBR240LT (2A/40V) Central Semiconductor CMSH1- 40M (1A/40V) www.centralsemi.com SHUTDOWN AND START-UP On startup, the LM3502 contains special circuitry that limits the peak inductor current which prevents large current spikes from loading the battery or power supply. When Cntrl ≥ 1.4V and both the En1 and En2 signals are less than 0.3V, the LM3502 will enter a low IQ state and regulation will end. During this low IQ mode the output voltage is a diode drop below the supply voltage and the soft-start will be reset to limit the peak inductor current at the next startup. When both En1 and En2 are less than 0.3V, the P1 PMOS and N2 NMOS switches will turn off. When Cntrl < 0.3V for more than 12ms, typicaly, the LM3502 will shutdown and the output voltage will be a diode drop below the supply voltage. If the Cntrl pin is low for more than 12ms, the soft-start will reset to limit the peak inductor current at the next startup. When Cntrl is < 0.3 but for less than 12ms, typically, the device will not shutdown and reset the soft-start but shut off the NMOS N1 Power Device to allow for PWM contrl of the LED current. THERMAL SHUTDOWN The LM3502 stops regulating when the internal semiconductor junction temperature reaches approximately 140°C. The internal thermal shutdown has approximately 20°C of hysteresis which results in the LM3502 turning back on when the internal semiconductor junction temperature reaches 120°C. When the thermal shutdown temperature is reached, the softstart is reset to prevent inrush current when the die temperature cools. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 17 LM3502 SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 www.ti.com UNDER VOLTAGE PROTECTION The LM3502 contains protection circuitry to prevent operation for low input supply voltages. When Vin drops below 2.3V, typically the LM3502 will no longer regulate. In this mode, the output volage will be one diode drop below Vin and the softstart will be reset. When Vin increases above 2.4V, typically, the device will begin regulating again. OVER VOLTAGE PROTECTION The LM3502 contains dedicated circuitry for monitoring the output voltage. In the event that the LED network is disconnected from the LM3502, the output voltage will increase and be limited to 15.5V(typ.) for the 16V version , 24V(typ.) for the 25V version, 34V(typ.) for the 35V version and 42V(typ.) for the 44V version (see eletrical table for more details). In the event that the network is reconnected, regulation will resume at the appropriate output voltage. LAYOUT CONSIDERATIONS All components, except for the white LEDs, must be placed as close as possible to the LM3502. The die attach pad (DAP) must be soldered to the ground plane. The input bypass capacitor CIN, as shown in Figure 1, must be placed close to the IC and connect between the VIN and PGND pins. This will reduce copper trace resistance which effects input voltage ripple of the IC. For additional input voltage filtering, a 100nF bypass capacitor can be placed in parallel with CIN to shunt any high frequency noise to ground. The output capacitor, COUT, must be placed close to the IC and be connected between the VOUT1 and PGND pins. Any copper trace connections for the COUT capacitor can increase the series resistance, which directly effects output voltage ripple and efficiency. The current setting resistor, R1, should be kept close to the Fb pin to minimize copper trace connections that can inject noise into the system. The ground connection for the current setting resistor network should connect directly to the PGND pin. The AGND pin should be tied directly to the PGND pin. Trace connections made to the inductor should be minimized to reduce power dissipation and increase overall efficiency while reducing EMI radiation. For more details regarding layout guidelines for switching regulators, refer to Applications Note AN-1149. 18 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 LM3502 www.ti.com SNVS339B – SEPTEMBER 2005 – REVISED MAY 2013 REVISION HISTORY Changes from Revision A (May 2013) to Revision B • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 18 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM3502 19 PACKAGE OPTION ADDENDUM www.ti.com 16-Oct-2015 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM3502ITL-16/NOPB LIFEBUY DSBGA YPA 10 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 125 SANB LM3502ITL-25/NOPB LIFEBUY DSBGA YPA 10 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 125 SAPB LM3502ITL-44/NOPB LIFEBUY DSBGA YPA 10 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 125 SDLB LM3502SQ-16/NOPB LIFEBUY WQFN RGH 16 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L00048B LM3502SQ-25/NOPB LIFEBUY WQFN RGH 16 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L00049B LM3502SQ-35/NOPB LIFEBUY WQFN RGH 16 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L00044B LM3502SQ-44/NOPB LIFEBUY WQFN RGH 16 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L00050B (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 16-Oct-2015 (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 2-Sep-2015 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) LM3502ITL-16/NOPB DSBGA YPA 10 250 178.0 8.4 LM3502ITL-25/NOPB DSBGA YPA 10 250 178.0 LM3502ITL-44/NOPB DSBGA YPA 10 250 178.0 LM3502SQ-16/NOPB WQFN RGH 16 1000 LM3502SQ-25/NOPB WQFN RGH 16 LM3502SQ-35/NOPB WQFN RGH LM3502SQ-44/NOPB WQFN RGH 2.03 2.21 0.76 4.0 8.0 Q1 8.4 2.03 2.21 0.76 4.0 8.0 Q1 8.4 2.03 2.21 0.76 4.0 8.0 Q1 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 16 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 16 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 Pack Materials-Page 1 W Pin1 (mm) Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 2-Sep-2015 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3502ITL-16/NOPB DSBGA YPA 10 250 210.0 185.0 35.0 LM3502ITL-25/NOPB DSBGA YPA 10 250 210.0 185.0 35.0 LM3502ITL-44/NOPB DSBGA YPA 10 250 210.0 185.0 35.0 LM3502SQ-16/NOPB WQFN RGH 16 1000 210.0 185.0 35.0 LM3502SQ-25/NOPB WQFN RGH 16 1000 210.0 185.0 35.0 LM3502SQ-35/NOPB WQFN RGH 16 1000 210.0 185.0 35.0 LM3502SQ-44/NOPB WQFN RGH 16 1000 210.0 185.0 35.0 Pack Materials-Page 2 PACKAGE OUTLINE RGH0016A WQFN - 0.8 mm max height SCALE 3.500 WQFN 4.1 3.9 B A PIN 1 INDEX AREA 0.5 0.3 0.3 0.2 4.1 3.9 DETAIL OPTIONAL TERMINAL TYPICAL C 0.8 MAX SEATING PLANE (0.1) TYP 2.6 0.1 5 8 SEE TERMINAL DETAIL 12X 0.5 4 9 4X 1.5 1 12 16X PIN 1 ID (OPTIONAL) 13 16 16X 0.3 0.2 0.1 0.05 C A C B 0.5 0.3 4214978/A 10/2013 NOTES: 1. All linear dimensions are in millimeters. Dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT RGH0016A WQFN - 0.8 mm max height WQFN ( 2.6) SYMM 16 13 SEE DETAILS 16X (0.6) 16X (0.25) 1 12 (0.25) TYP SYMM (3.8) (1) 9 4 12X (0.5) 5X ( 0.2) VIA 8 5 (1) (3.8) LAND PATTERN EXAMPLE SCALE:15X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND METAL SOLDER MASK OPENING METAL SOLDER MASK OPENING NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DEFINED SOLDER MASK DETAILS 4214978/A 10/2013 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see QFN/SON PCB application report in literature No. SLUA271 (www.ti.com/lit/slua271). www.ti.com EXAMPLE STENCIL DESIGN RGH0016A WQFN - 0.8 mm max height WQFN SYMM (0.675) METAL TYP 13 16 16X (0.6) 16X (0.25) 12 1 (0.25) TYP (0.675) SYMM (3.8) 12X (0.5) 9 4 8 5 4X (1.15) (3.8) SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL EXPOSED PAD 78% PRINTED SOLDER COVERAGE BY AREA SCALE:15X 4214978/A 10/2013 NOTES: (continued) 5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. www.ti.com MECHANICAL DATA YPA0010 0.600 ±0.075 D E TLP10XXX (Rev D) D: Max = 2.124 mm, Min =2.063 mm E: Max = 1.946 mm, Min =1.885 mm 4215069/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. 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