NX4108 1A SYNCHRONOUS BUCK SWITCHER WITH FET ON BOARD PRODUCTION DATA SHEET Pb Free Product DESCRIPTION FEATURES n n n n n The NX4108 is a current mode PWM buck switcher with internal compensation, can provide up to 1A output current with FET on board. It operates from 2.8V to 5.5V and output as low as 0.6V which is ideal for the application with single cell Li-Ion battery as well as other 3.3V input bus supply applications. Switching frequency is fixed 1MHz, small surface mount inductors and capaci- n tors are allowed to use, make it good for portable appli- n n cations. NX4108 is available in 5-pin SOT23 package. n n n n SOT23-5L package Internal Digital Soft Start Internally-compensated Current Mode Controller <1uA Shut-down Current Peak Current Limit with HICCUP Feature and Over Temperature Protection Prebias Start-up Operation Enable Available Pb-free and RoHS Compliant APPLICATIONS Li-Ion Battery Operated Portable System Cellular Phones Portable Applications USB Devices TYPICAL APPLICATION VIN=5V 1 FB NX4108 5 EN VIN SW GND 4 3 22uF(X5R,6.3V) 2.2uH 2 Vout=2.5V 10uF (X5R,6.3V) 332k 105k Figure1 - Typical application of NX4108CZ1TR ORDERING INFORMATION Device NX4108CZ1TR Rev. 1.7 12/30/09 Temperature -40oC to 85oC Package SOT23-5L Pb-Free Yes Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 1 NX4108 ABSOLUTE MAXIMUM RATINGS VIN to GND ..................................................................... -0.3V to 6V SW,FB,EN to GND ........................................................... -0.3V to VIN + 0.3V ESD Susceptibility ............................................................. 1kV Lead Temperature(Soldering,10sec.) .................................... 300oC Storage Temperature Range ................................................ -55oC to 150oC Operating Junction Temperature Range ................................ -40oC to 150oC CAUTION: Stresses above those listed in "ABSOLUTE MAXIMUM RATINGS", may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. PACKAGE INFORMATION 5-LEAD PLASTIC SOT23 θJA ≈ 110o C/W EN 1 GND 2 SW 3 5 FB 4 VIN ELECTRICAL SPECIFICATIONS VIN=3.5V. Typical data refers to TA= 25oC. Unless otherwise specified. PARAMETER Reference Voltage Ref Voltage Line Regualtion Line Regulation SYM Test Condition VFB Min TYP MAX Units 0.59 0.6 0.607 V VIN=3V to 5V,VOUT=1.8V, IOUT=10mA VIN UVLO VIN Rising Threshold VIN Falling Threshold Supply Voltage(VIN) VIN Input Voltage Range Shutdown Current Quiescent Current Oscillator (Rt) Frequency 2 2.3 2.5 VIN I shutdown Iq 2.8 EN=GND No Load, switching FS 1 4 800 78 1000 5.5 2.5 1200 500 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 V uA mA kHz % nS 0.05 Tss V V 90 100 Error Amplifiers Feedback Input Bias Current SS Rev. 1.7 12/30/09 2.8 2.3 Max Duty Cycle Min ON time Soft Start time mV uA uS 2 NX4108 PARAMETER Current Limit Current Limit Threshold Thermal Shutdown Thermal shutdown trip point Hysteresis Internal Switch Rdson of Control FET Rdson of Synchronous FET SYM Test Condition Min TYP MAX Units 1.8 A o 155 15 Vin=5V Vin=3.3V Vin=5V Vin=3.3V Enable En low Threshold voltage En high Threshold voltage o C C mohm 400 480 300 360 mohm 0.4 1.4 V V PIN DESCRIPTIONS PIN SYMBOL SW GND Ground Connection for Chip. Connect GND with large copper areas to the input and output supply returns, and negative terminals of the input and output capacitors. FB Error amplifier inverting input. Error amplifier inverting input. This pin is connected via resistor dividers to the output of the switching regulators to set the output DC voltage. A 332kohm resistor is recommended to be connected from VOUT and FB . VIN Supply voltage input for switcher. EN Rev. 1.7 12/30/09 PIN DESCRIPTION SW output. Junction of the internal high-side and low-side power MOSFETs, and output inductor. Enable input. Set this pin to GND or less than 0.4V will shut down the regulator. Enable signal can not be high when VIN is low. Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 3 NX4108 BLOCK DIAGRAM Thermal Shutdown UVLO POR EN Vref Bias Generator 3 cycle counter POR VIN OCPB + - CLK VIN Soft start Hiccup timer OSC 70ns one shot reset dom S Q R + start Vref PWM FB PWM comparator 1Mohm OCPB POR 20pF Control Logic SW VIN LDen GND Figure 2 - Simplified block diagram of the NX4108 Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 4 NX4108 Typical Operating Characteristics R e ference voltage vs tem p e rature 0.604 0.603 Reference voltage(V) 0.602 0.601 0 .6 0.599 0.598 0.597 0.596 0.595 0.594 0.593 0 20 40 60 80 100 120 140 160 t e m p e r a t u r e (°C ) Fig.3 - Reference volateg vs temperature Normalized frequency vs temperature Normalized Frequency 1 0.98 0.96 0.94 0.92 0.9 0 20 40 60 80 100 120 140 160 temperature(°C) Fig.4 - Normalized frequency vs temperature Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 5 NX4108 Typical Application( VOUT=2.5V) VIN=5V 1 FB NX4108 5 EN VIN SW GND 4 3 22uF(X5R,6.3V) 2.2uH Vout=2.5V 10uF (X5R,6.3V) 2 332k 105k Figure 5 - Demo board schematic Figure 6 - Output ripple Figure 7 - Transient response Figure 8 - Efficiency Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 6 NX4108 Typical Application( VOUT=1.8V) VIN=5V 1 FB NX4108 5 EN VIN SW GND 4 3 22uF(X5R,6.3V) 2.2uH Vout=1.8V 10uF (X5R,6.3V) 2 332k 165k Figure 9 - Demo board schematic Figure 10 - Output ripple Figure 11 - Transient response Figure12 - Efficiency Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 7 NX4108 Typical Application( VOUT=1.2V) VIN=5V 1 FB NX4108 5 EN VIN SW GND 4 3 22uF(X5R,6.3V) 2.2uH Vout=1.2V 10uF (X5R, 6.3V) 2 332k 332k Figure 13 - Demo board schematic Figure 14 - Output ripple Figure 15 - Transient response Figure 17 - Shutdown Figure 16 - Startup Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 8 NX4108 Typical Application( VOUT=1.2V) Figure 18 - Efficiency Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 9 NX4108 Demoboard Layout U1 VIN 1 VIN 4 C1 22u VIN SW 3 1 L1 VOUT 2 C2 10u NX4108 FB GND 332k GND EN R1 5 R2 105k 2 1 VOUT DO1608C-222 Figure 19 - Demoboard schematic Figure 20- Top layer Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 10 NX4108 Figure 21- Gound layer Figure 22- Power layer Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 11 NX4108 Figure 22- Bottom layer Rev. 1.7 12/30/09 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 12