ncp1521 ON Semiconductor, ncp1521 Datasheet
ncp1521
Available stocks
Related parts for ncp1521
ncp1521 Summary of contents
Page 1
... High-Ef ficiency, Low Quiescent Current, Adjustable Output Voltage Step-Down Converter The NCP1521 step- down PWM DC- DC converter is optimized for portable applications powered from one cell Li- ion or three cell Alkaline/NiCd/NiMH batteries. The device is available in an adjustable output voltage from 0 3 uses synchronous rectification to increase efficiency and reduce external part count ...
Page 2
... Figure 2. Efficiency vs. Output Current Vbattery VIN PWM/PFM 1 CONTROL 4.7 mF GND 2 LOGIC CONTROL Enable EN & THERMAL 3 SHUTDOWN Figure 3. Simplified Block Diagram NCP1521 V = 3.3 V out 25°C A 100 200 300 400 500 I (mA) out ILIMIT FB 4 REFERENCE VOLTAGE http://onsemi ...
Page 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. NCP1521 Description Power Supply Input for Analog Ground connection for the NFET Power Stage and the Analog Sections of the IC ...
Page 4
... EN << H >> Input Current 3.6 V Soft-Start Time Thermal Shutdown Threshold Thermal Shutdown Hysteresis 5. The overall output voltage tolerance depends upon the accuracy of the external resistor (R1, R2). NCP1521 (Typical values are referenced +25°C, Min and Max values are referenced -40° 3 http://onsemi ...
Page 5
... IN Figure 7. Shutdown Current vs. Supply Voltage 100 T = -40° 100 200 300 I , OUTPUT CURRENT (mA) OUT Figure 9. Efficiency vs. Output Current ( 3.6 V) OUT IN NCP1521 100 OUT 0 5.2 5.7 -40 -20 Figure 6. Quiescent Current vs. Temperature 100 95 90 ...
Page 6
... Figure 11. Soft Start Time (V 1.8 1.7 1.6 1.5 1.4 1 300 mA OUT 1.2 -40 - TEMPERATURE (°C) Figure 13. Frequency vs. Temperature 2.0 1.5 1.0 0.5 0.0 0 0.2 0.4 0.6 0 ENABLE INPUT VOLTAGE (V) IN Figure 15. Output Voltage vs. Enable Input Pin Voltage NCP1521 1.8 1.7 1.6 1.5 1.4 1.3 2.7 3.2 = 3.6 V) Figure 12. Frequency vs. Input Voltage IN 3.0 2 0.9 V OUT 2.0 1.5 V OUT 1 5 0.5 0 3.3 V -0.5 OUT -1 3 ...
Page 7
... OUT 0 600 mA OUT -0.5 -1 -2.0 - TEMPERATURE (°C) Figure 19. Output Voltage Accuracy (V = 3.3 V) OUT 10 ms/Div Figure 21. Load Transient Response in PWM Operation ( NCP1521 2.0 1.5 1.0 0.5 0.0 -0.5 -1 -2.0 100 150 -50 Figure 18. Output Voltage Accuracy = 300 mA 100 150 Figure 20. Load Transient Response in PWM V 2.5 ms/Div OUT 50 mV/Div ...
Page 8
... V or higher. PWM Operating Mode In this mode, the output voltage of the NCP1521 is regulated by modulating the on-time pulse width of the main switch fixed frequency of 1.5 MHz. The switching of the PMOS Q1 is controlled by a flip-flop ...
Page 9
... When the short circuit condition is removed, the device returns to the normal mode of operation. Soft-Start The NCP1521 uses soft-start (300 ms Typ) to limit the inrush current when the device is initially enabled. Soft-start is implemented by gradually increasing the reference voltage until it reaches the full reference voltage. ...
Page 10
... JMK212BY475MG TDK C2012X5ROJ475KB C1632X5ROJ475KT Output L-C Filter Design Considerations The NCP1521 is built in 1.5 MHz frequency and uses current mode architecture. The correct selection of the 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. ...
Page 11
... SW C OUT In PFM mode (at light load), the output voltage is regulated by pulse frequency modulation. The output voltage ripple is independent of the output capacitor value set by the threshold of PFM comparator. NCP1521 Table 4. List of Output Capacitor Murata Taiyo Yuden LPO3010 TDK Feed-Forward Capacitor Selection The feed-forward capacitor sets the feedback loop response and is critical to obtain good loop stability ...
Page 12
... Separate the feedback path of the output voltage from the power path. Keep this path close to the NCP1521 circuit. And also route it away from noisy components. This will prevent noise from coupling into the voltage feedback trace. 4. Place the DC-DC converter away from noise sensitive circuitry, such as RF circuits ...
Page 13
... U1 J1 VFVIN VIN GND 4.7 mF Power NCP152x 0 NCP1521 2 CON3 220 K BNCH 0 0 Figure 27. Schematics Figure 28. Silkscreen Layer http://onsemi.com 13 OUTPUT VOUT 220 K R2 220 K ...
Page 14
... NCP1521 Figure 29. Board Layout (Top View) Figure 30. Board Layout (Bottom View) http://onsemi.com 14 ...
Page 15
... Bill of Materials Item Part Description 1 NCP1521 DC-DC Converter 4.7 mF Ceramic Capacitor 2 6.3 V X5R 10 mF Ceramic Capacitor 3 6.3 V X5R 4 SMD Resistor 220 K 5 SMD Inductor 6 I/O Connector can be plugged by BLZ5.08/2 (Weidmüller reference) 7 Jumper Header vertical mount 3*1, 2. Jumper Connector, 400 mils NCP1521 Ref PCB Footprint ...
Page 16
... IN THIS LOCATION. TRIMMED LEAD NOT TO EXTEND MORE THAN 0.2 FROM BODY. MILLIMETERS DIM MIN MAX A 3.00 BSC B 1.50 BSC C 0.90 1.10 D 0.25 0.50 G 0.95 BSC H 0.01 0.10 J 0.10 0.26 K 0.20 0.60 L 1.25 1. 2.50 3.00 2.4 0.094 mm SCALE 10:1 inches ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your loca Sales Representative NCP1521/D ...