NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 Series 1.7MHz, 1A, High Efficiency, Low Ripple, Adjustable Output Voltage Step-down Converter Evaluation Board User's Manual http://onsemi.com EVAL BOARD USER’S MANUAL Overview allowing a small inductor and capacitors. Automatic switching PWM/PFM mode offers improved system efficiency. Additional features include integrated soft−start, cycle−by−cycle current limiting and thermal shutdown protection. The NCP1529 is available in a space saving, low profile 2x2 x 0.5 mm UDFN6 package and TSOP−5 package. The NCP1529 step−down DC−DC converter is a monolithic integrated circuit for portable applications powered from one cell Li−ion or three cell Alkaline/NiCd/NiMH batteries. The device – available in an adjustable output voltage from 0.9 V to 3.9 V – is able to deliver up to 1 A. It uses synchronous rectification to increase efficiency and reduce external part count. The device also has a built−in 1.7 MHz (nominal) oscillator which reduces component size by Figure 1. NCP1529ASNT1GEVB Board Picture in TSOP−5 © Semiconductor Components Industries, LLC, 2012 April, 2012 − Rev. 1 Figure 2. NCP1529MUTBGEVB Board Picture in UDFN−6 1 Publication Order Number: EVBUM2106/D NCP1529ASNT1GEVB, NCP1529MUTBGEVB Table 1. MAXIMUM RATINGS Symbol Value Unit Minimum Voltage All Pins Rating Vmin −0.3 V Maximum Voltage All Pins (Note 1) Vmax 7.0 V Maximum Voltage EN, ENI2C, SDA, SCL Vmax VIN + 0.3 V Thermal Resistance, Junction−to−Air (TSOP−5 Package) Thermal Resistance using TSOP−5 Recommended Board Layout (Note 8) RqJA 300 110 °C/W Thermal Resistance, Junction−to−Air (UDFN6 Package) Thermal Resistance using UDFN6 Recommended Board Layout (Note 8) RqJA 220 40 °C/W Operating Ambient Temperature Range (Notes 6 and 7) TA −40 to 85 °C Storage Temperature Range Tstg −55 to 150 °C Junction Operating Temperature (Notes 6 and 7) TJ −40 to 125 °C Latchup Current Maximum Rating (TA = 85°C) (Note 4) Other Pins Lu $100 mA 2.0 200 kV V 1 per IPC ESD Withstand Voltage (Note 3) Human Body Model Machine Model Vesd Moisture Sensitivity Level (Note 5) MSL Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. 1. Maximum electrical ratings are defined as those values beyond which damage to the device may occur at TA = 25°C. 2. According to JEDEC standard JESD22−A108B. 3. This device series contains ESD protection and exceeds the following tests: Human Body Model (HBM) per JEDEC standard: JESD22−A114. Machine Model (MM) per JEDEC standard: JESD22−A115. 4. Latchup current maximum rating per JEDEC standard: JESD78. 5. JEDEC Standard: J−STD−020A. 6. In applications with high power dissipation (low VIN, high IOUT), special care must be paid to thermal dissipation issues. Board design considerations − thermal dissipation vias, traces or planes and PCB material − can significantly improve junction to air thermal resistance RqJA (for more information, see design and layout consideration section). Environmental conditions such as ambient temperature TA brings thermal limitation on maximum power dissipation allowed. The following formula gives calculation of maximum ambient temperature allowed by the application: TA MAX = TJ MAX − (RqJA x Pd) Where: TJ is the junction temperature, Pd is the maximum power dissipated by the device (worst case of the application), and RqJA is the junction−to−ambient thermal resistance. 7. To prevent permanent thermal damages, this device include a thermal shutdown which engages at 180°C (typ). 8. Board recommended TSOP−5 and UDFN−6 layouts are described on Layout Considerations section. ELECTRICAL CHARACTERISTICS For Electrical Characteristic, please report to our NCP1529 datasheet available on our website: http://onsemi.com. http://onsemi.com 2 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Table 2. NCP1529 − BOARD CONNECTIONS Symbol Switch Descriptions INPUT POWER VIN+ This is the positive connection for power supply. VIN− This is the return connection for the power supply GND1, GND2 Ground clip SETUP ENABLE SELECT (UDFN package) To enable the buck converter, connect a shorting jumper between ENABLE−1 and ENABLE−2. To disable the buck converter, connect a shorting jumper between ENABLE−3 and ENABLE−2. A shorting jumper must be used to select an output voltage of 1.2V or an adjustable output voltage. OUTPUT POWER VOUT+ This is the positive connection of the output voltage. VOUT− This is the return connection of the output voltage. TEST POINT TPVIN This is the test point of the input voltage. TPEN This is the test point of the enable pin. TPSW This is the test point of the inductor voltage. TPVOUT This is the test point of the output voltage. http://onsemi.com 3 NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 − BOARD SCHEMATIC VIN VIN ENABLE S1 VIN+ VIN 1 CON1 VIN− NCP1529 1 2 3 C1 10uF 1 EN EN VIN EN1 EN1 1 2 0 REN 2meg SW 3 EN FB 5 FB 4 VIN GND SW VIN NCP1529 CON1 0 D1 FIX 0 D2 FIX 0 D3 FIX 0 LX LX D4 FIX VOUT VOUT 0 0 VOUT+ 2.2mH VOUT 0 R1 220k FB 0 C3 18pF 1 CON1 C2 10uF P2 1meg VOUT− 1 0 CON1 1 GND2 JMP 0 0 0 2 GND1 JMP 2 1 0 L 1 1 1 1 SW 0 0 Figure 3. Board Schematic in TSOP−5 VIN VIN ENABLE S1 VIN+ VIN 1 CON1 VIN− C1 4.7uF 1 EN EN VIN U1 1 2 3 EN FB 1 2 0 VIN 3 FB EN GND SW VIN GND 6 EN 5 SW 4 0 NCP1529U CON1 0 0 0 LX LX VOUT VOUT SW L P 1meg GND2 JMP CON1 C2 10uF 0 J1 CON4A 2 0 1 3 2 0 C3 18pF 0 0 Figure 4. Board Schematic in UDFN6 http://onsemi.com 4 1 VOUT− 1 CON1 2 4 GND1 JMP 1 1 R2 150k 0 VOUT R1 150k FB 0 VOUT+ 2.2mH 0 NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 − TEST PROCEDURE Equipment Needed 3. Connect Vin+ to power supply and Vin− to ground. The DC current measurement on Vin+ line should be around 0.3 mA. 4. For the UDFN6 package, close the SELECT connector to the potentiometer. 5. Close EN connector. 6. Modify P2 potentiometer to get Vout to 1.2 V. Output voltage value is defined by : Vout = 0.6 x (1 + R1/R2) 7. The DC current measurement on Vin+ line should be around 36 mA. The part operates in PFM mode: Power supply Digital Volt Meter Digital Amp Meter Test 1. Jumper ENABLE (and SELECT for the UDFN6 package) should be open. 2. Set the power supply to 3.6 V and the current limit of at least 1.5 A. VSW Vout = 1.2 V Figure 5. VSW and Vout in PFM Mode http://onsemi.com 5 NCP1529ASNT1GEVB, NCP1529MUTBGEVB 8. Increase Output current to 1 A. The part works in PWM mode with a low ripple: VSW Vout = 1.2 V Figure 6. VSW and Vout in PWM Mode 9. Remove J5 connector. The DC current measurement on Vp line should be back around 0.3 mA. NCP1529 − COMPONENTS SELECTION Input Capacitor Selection output filter ensures good stability and fast transient response. Due to the nature of the buck converter, the output L−C filter must be selected to work with internal compensation. For NCP1529, the internal compensation is internally fixed and it is optimized for an output filter of L = 2.2 mH and COUT = 10 mF. The corner frequency is given by: In PWM operating mode, the input current is pulsating with large switching noise. Using an input bypass capacitor can reduce the peak current transients drawn from the input supply source, thereby reducing switching noise significantly. The capacitance needed for the input bypass capacitor depends on the source impedance of the input supply. The maximum RMS current occurs at 50% duty cycle with maximum output current, which is IO, max/2. For NCP1529, a low profile ceramic capacitor of 4.7 mF should be used for most of the cases. For effective bypass results, the input capacitor should be placed as close as possible to the VIN Pin fc + GRM188R60J475KE 4.7 mF GRM21BR71C475KA Taiyo Yuden TDK JMK212BY475MG 4.7 mF C2012X5R0J475KT 4.7 mF 2p ǸL C OUT + 1 2p Ǹ2.2 mH 10 mF + 34 kHz (eq. 1) The device operates with inductance value of 2.2 mH. If the corner frequency is moved, it is recommended to check the loop stability depending of the accepted output ripple voltage and the required output current. Take care to check the loop stability. The phase margin is usually higher than 45°. Table 3. LIST OF INPUT CAPACITOR Murata 1 Table 4. L−C FILTER EXAMPLE Inductance (L) C1608X5R0J475KT Output L−C Filter Design Considerations The NCP1529 operates at 1.7 MHz frequency and uses current mode architecture. The correct selection of the http://onsemi.com 6 Output Capacitor (COUT) 2.2 mH 10 mF 4.7 mH 4.7 mF NCP1529ASNT1GEVB, NCP1529MUTBGEVB Inductor Selection Output Capacitor Selection The inductor parameters directly related to device performances are saturation current and DC resistance and inductance value. The inductor ripple current (DIL) decreases with higher inductance: Selecting the proper output capacitor is based on the desired output ripple voltage. Ceramic capacitors with low ESR values will have the lowest output ripple voltage and are strongly recommended. The output capacitor requires either an X7R or X5R dielectric. The output ripple voltage in PWM mode is given by: DI L + V OUT L f SW ǒ 1* Ǔ V OUT V IN (eq. 2) • DIL: Peak to peak inductor ripple current • L: Inductor value • fSW: Switching frequency DV OUT + DI L The saturation current of the inductor should be rated higher than the maximum load current plus half the ripple current: I L(max) + I O(max) ) DI L Murata Taiyo Yuden TDK The inductor’s resistance will factor into the overall efficiency of the converter. For best performances, the DC resistance should be less than 0.3 W for good efficiency. C OUT ) ESR Ǔ (eq. 4) GRM188R60J475KE 4.7 mF GRM188R60OJ106ME 10 mF JMK212BY475MG 4.7 mF JMK212BJ106MG 10 mF C2012X5R0J475 4.7 muF C1608X5R0J475 C2012X5R0J106 10 mF Feed−Forward Capacitor Selection Table 5. LIST OF INDUCTOR FDK MIPW3226 Series TDK VLF3010AT Series The feed−forward capacitor sets the feedback loop response and is critical to obtain good loop stability. Given that the compensation is internally fixed, an 18 pF ceramic capacitor is needed. Choose a small ceramic capacitor X7R or X5R or COG dielectric. TFC252005 Series Coil Craft 1 f SW GRM21BR71C475KA • IL(max): Maximum inductor current • IO(max): Maximum Output current Taiyo Yuden 4 Table 6. LIST OF OUTPUT CAPACITOR (eq. 3) 2 ǒ LQ CBL2012 DO1605−T Series LPS3008 NCP1529 − BILL OF MATERIAL Table 7. BOM IN TSOP−5 PACKAGE Designator Qty Description Value Tolerance Footprint Manufacturer Manufacturer Part Number U1 1 IC, Converter, DC/DC NA NA TSOP−5 ON Semiconductor NCP1529 C1 1 Ceramic Capacitor 4.7 mF, 6.3 V, X5R 10% 0603 TDK C1608X5R0J475 C2 1 Ceramic Capacitor 10 mF, 6,3 V, X5R 10% 0603 TDK C1608X5R0J106 C3 1 Ceramic Capacitor 18 pF, 50 V, COG 5% 0603 TDK C1608C0G1H180 R1 1 SMD Resistor 110k 1% 0603 std std P2 1 Potentiometer 1meg 10% Vishay Spectrol 63M−T607−105 L1 1 Inductor 2,2 mH 20% 1605 Coilcraft DO1605T−222MLB VIN, VOUT 4 Connector NA NA NA Emerson Network Power Connectivity Solutions 111−2223−001 http://onsemi.com 7 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Table 7. BOM IN TSOP−5 PACKAGE Designator Qty Description Value Tolerance Footprint Manufacturer Manufacturer Part Number ENABLE 1 3 Pin Jumper Header NA NA 2,54mm TYCO/AMP Molex/Waldom 5−826629−0 90120−0160 GND1, GND2 2 Jumper for GND NA NA 10.16mm Harwin Molex / Waldom D3082−01 90120−0160 EN, SW, VIN, VOUT 4 Test Point Type 3 NA NA f 1.60mm Keystone 5010 PCB 1 87 mm x 57 mm x 1.0 mm 4 Layers NA NA NA Any TLS−P−003−A−0907 −BBR Table 8. BOM IN UDFN−6 PACKAGE Designator Qty Description Value Tolerance Footprint Manufacturer Manufacturer Part Number U1 1 IC, Converter, DC/DC NA NA UDFN6 ON Semiconductor NCP1529 C1 1 Ceramic capacitor 4.7 mF, 6.3 V, X5R 10% 0603 TDK C1608X5R0J475 C2 1 Ceramic capacitor 10 mF, 6.3 V, X5R 10% 0603 TDK C1608X5R0J106 C3 1 Ceramic capacitor 18 pF, 50 V, COG 5% 0603 TDK C1608C0G1H180 R1, R2 2 SMD resistor 150k 1% 0603 std std P2 1 Potentiometer 1meg 10% Vishay Spectrol 63M−T607−105 L1 1 Inductor 2.2 mH 20% 1605 Coilcraft DO1605T−222MLB VIN, VOUT 4 Connector NA NA NA Emerson Network Power Connectivity Solutions 111−2223−001 ENABLE 1 3 Pin Jumper Header NA NA 2,54mm TYCO/AMP Molex/Waldom 5−826629−0 90120−0160 SELECT J1 2x2 Pin Jumper Header NA NA 2,54mm TYCO/AMP Molex/Waldom 6−166591−5 90131−0140 GND1, GND2 2 Jumper for GND NA NA 10,16mm Harwin Molex/Waldom D3082−01 90120−0160 EN, SW, VIN, VOUT 4 Test point type 3 NA NA f 1,60mm Keystone 5010 PCB 1 87mm x 57mm x 1.0 mm 4 Layers NA NA NA Any TLS−P−003−A−0907 −BBR http://onsemi.com 8 NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 − PCB LAYOUT GUIDELINES LAYOUT CONSIDERATIONS Electrical Layout Considerations participates to the good loop stability. A 18pF capacitor is recommended to meet compensation requirements. A four layer PCB with a ground plane and a power plane will help NCP1529 noise immunity and loop stability. Implementing a high frequency DC−DC converter requires respect of some rules to get a powerful portable application. Good layout is key to prevent switching regulators to generate noise to application and to themselves. Electrical layout guide lines are: • Use short and large traces when large amount of current is flowing. • Keep the same ground reference for input and output capacitors to minimize the loop formed by high current path from the battery to the ground plane. • Isolate feedback pin from the switching pin and the current loop to protect against any external parasitic signal coupling. Add a feed−forward capacitor between VOUT and FB which adds a zero to the loop and Thermal Layout Considerations High power dissipation in small package leads to thermal consideration such as: • Enlarge VIN trace and added several vias connected to power plane. • Connect GND pin to top plane. • Join top, bottom and each ground plane together using several free vias in order to increase radiator size. For high ambient temperature and high power dissipation requirements, UDFN6 package using exposed pad connected to main radiator is recommended. Refer to Notes 6, 7, and 8. VOUT Trace EN Trace FB Trace VIN Trace SW Trace SW Trace VIN Trace FB Trace VOUT Trace GND Plane GND Plane EN Trace Figure 7. TSOP−5 Recommended Board Layout Figure 8. UDFN6 Recommended Board Layout http://onsemi.com 9 NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 − PCB LAYOUT OF TSOP−5 DEMO BOARD Board reference: TLS−P−003−A−0907−BBR Figure 9. Assembly Layer in TSOP−5 Figure 10. Part Layout in TSOP−5 http://onsemi.com 10 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Figure 11. Top Layer Routing in TSOP−5 Figure 12. Ground Layer Routing in TSOP−5 http://onsemi.com 11 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Figure 13. Power Layer Routing in TSOP−5 Figure 14. Bottom Layer Routing in TSOP−5 http://onsemi.com 12 NCP1529ASNT1GEVB, NCP1529MUTBGEVB NCP1529 − PCB LAYOUT OF UDFN−6 DEMO BOARD Board reference: TLS−P−003−A−0907−BBR Figure 15. : Assembly Layer in UDFN6 Figure 16. Part Layout in UDFN−6 http://onsemi.com 13 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Figure 17. Top Layer Routing in UDFN−6 Figure 18. Ground Layer Routing in UDFN6 http://onsemi.com 14 NCP1529ASNT1GEVB, NCP1529MUTBGEVB Figure 19. Power Layer Routing in UDFN−6 Figure 20. Bottom Layer Routing in UDFN6 http://onsemi.com 15 NCP1529ASNT1GEVB, NCP1529MUTBGEVB ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). 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