600mA Step-Down DC-DC Converter

LM3674 2MHz, 600mA Step-Down DC-DC Converter in SOT 23-5 January 2006 LM3674 2MHz, 600mA Step-Down DC-DC Converter in SOT 23-5 General Description The LM3674 step-down DC-DC converter is optimized for powering low voltage circuits from a single Li-Ion cell battery and input voltage rails from 2.7V to 5.5V. It provides up to 600mA load current, over the entire input voltage range. There are several fixed output voltages and adjustable output voltage versions. The device offers superior features and performance for mobile phones and similar portable systems. During PWM mode, the device operates at a fixed-frequency of 2 MHz (typ). Internal synchronous rectification provides high efficiency during PWM mode operation. In shutdown mode, the device turns off and reduces battery consumption to 0.01 µA (typ). The LM3674 is available in SOT23-5 in leaded (PB) and lead-free (NO PB) versions. A high switching frequency of 2 MHz (typ) allows use of only three tiny external surfacemount components, an inductor and two ceramic capacitors. Features n 600mA max load current n Input voltage range from 2.7V to 5.5V n Available in fixed and adjustable output voltages ranging from 1.0V to 3.3V n Operates from a single Li-Ion cell Battery n Internal synchronous rectification for high efficiency n Internal soft start n 0.01 µA typical shutdown current n 2 MHz PWM fixed switching frequency (typ) n SOT23-5 package n Current overload protection and Thermal shutdown protection Applications n n n n n n n Mobile phones PDAs MP3 players Portable instruments W-LAN Digital still cameras Portable Hard disk drives Typical Application 20167201 FIGURE 1. Typical Application Circuit © 2006 National Semiconductor Corporation DS201672 www.national.com LM3674 Typical Application (Continued) 20167230 FIGURE 2. Typical Application Circuit Connection Diagram and Package Mark Information SOT23-5 Package NS Package Number MF05A 20167202 Note: The actual physical placement of the package marking will vary from part to part. FIGURE 3. Top View Pin Descriptions Pin # 1 2 3 4 Name VIN GND EN FB Description Power supply input. Connect to the input filter capacitor ( Figure 1). Ground pin. Enable input. The device is in shutdown mode when voltage to this pin is < 0.4V and enable when > 1.0V. Do not leave this pin floating. Feedback analog input. Connect to the output filter capacitor for fixed voltage versions. For adjustable version external resistor dividers are required ( Figure 2). The internal resistor dividers are disabled for the adjustable version. Switching node connection to the internal PFET switch and NFET synchronous rectifier. 5 SW www.national.com 2 LM3674 Ordering Information Voltage Option (V) 1.2 Order Number (Level 95) LM3674MF-1.2 LM3674MFX-1.2 LM3674MF-1.2 LM3674MFX-1.2 1.5 LM3674MF-1.5 LM3674MFX-1.5 LM3674MF-1.5 LM3674MFX-1.5 1.8 LM3674MF-1.8 LM3674MFX-1.8 LM3674MF-1.8 LM3674MFX-1.8 ADJ LM3674MF-ADJ LM3674MFX-ADJ LM3674MF-ADJ LM3674MFX-ADJ NO PB NO PB SLTB NO PB NO PB SLHB NO PB NO PB SLSB SPEC NO PB NO PB Package Marking SLRB Supplied As (#/reel) 1000 3000 1000 3000 1000 3000 1000 3000 1000 3000 1000 3000 1000 3000 1000 3000 3 www.national.com LM3674 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN Pin: Voltage to GND EN, FB, SW Pin: Continuous Power Dissipation Junction Temperature (TJ-MAX) Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec.) ESD Rating (Note 3) Human Body model: All Pins Machine Model: All Pins 2 kV 200V −0.2V to 6.0V (GND−0.2V) to (VIN + 0.2V) Internally Limited +125˚C −65˚C to +150˚C 260˚C Operating Ratings (Notes 1, 2) Input Voltage Range (Note 11) Recommended Load Current Junction Temperature (TJ) Range Ambient Temperature (TA) Range 2.7V to 5.5V 0A to 600 mA −30˚C to +125˚C −30˚C to +85˚C Thermal Properties Junction-to-Ambient Thermal Resistance (θJA) (SOT23-5) for a 2 layer board (Note 6) 250˚C/W Junction-to-Ambient Thermal Resistance (θJA) (SOT23-5) for a 4 layer board (Note 6) 130˚C/W Electrical Characteristics (Notes 2, 9, 10) Limits in standard typeface are for TJ = 25˚C. Limits in boldface type apply over the full operating junction temperature range (−30˚C ≤ TJ ≤ 125˚C). Unless otherwise noted, specifications apply to the LM3674 with VIN = EN = 3.6V Symbol Parameter Feedback Voltage (Note 12) Line Regulation VFB Load Regulation VREF ISHDN IQ RDSON (P) RDSON (N) ILIM VIH VIL IEN FOSC Internal Reference Voltage Shutdown Supply Current DC Bias Current into VIN Pin-Pin Resistance for PFET Pin-Pin Resistance for NFET Switch Peak Current Limit Logic High Input Logic Low Input Enable (EN) Input Current Internal Oscillator Frequency PWM Mode 1.6 0.01 2 Condition IO = 10mA 2.7V ≤ VIN ≤ 5.5V IO = 100 mA 100 mA ≤ IO ≤ 600 mA VIN = 3.6V (Note 7) EN = 0V No load, device is not switching (FB=0V) ISW = 200mA ISW = 200mA Open Loop (Note 8) 830 1.0 0.4 1 2.6 Min -4 0.083 0.0010 0.5 0.01 300 380 250 1020 1 600 500 400 1200 Typ Max +4 Units % %/V %/mA V µA µA mΩ mΩ mA V V µA MHz Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: 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 (MIL-STD-883 3015.7). National Semiconductor recommends that all intergrated circuits be handled with appropriate precautions. Failure to observe proper ESD handling techniques can result in damage. Note 4: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ = 150˚C (typ.) and disengages at TJ = 130˚C Note 5: In Applications where high power dissipation and /or poor package resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX ) is dependent on the maximum operating junction temperature (TJ-MAX ), the maximum power dissipation of the device in the application (PD-MAX ) and the junction to ambient thermal resistance of the package (θJA) in the application, as given by the following equation: TA-MAX = TJ-MAX(θJA x PD-MAX). Refer to Dissipation ration table for PD-MAX values at different ambient temperatures. Note 6: Junction to ambient thermal resistance is highly application and board layout dependent. In applications where high power dissipation exists, special care must be given to thermal dissipation issues in board design. Value specified here 250˚C/W is based on measurement results using a 2 layer, 4" X 3", 2 oz. Cu board as per JEDEC standards. The (θJA) is 130˚C/W if a 4 layer, 4" X 3", 2/1/1/2 oz. Cu board as per JEDEC standards is used. Note 7: For the ADJ version the resistor dividers should be selected such that at the desired output voltage, the voltage at the FB pin is 0.5V. Note 8: Refer to datasheet curves for closed loop data and its variation with regards to supply voltage and temperature. Electrical Characteristic table reflects open loop data (FB=0V and current drawn from SW pin ramped up until cycle by cycle current limit is activated). Closed loop current limit is the peak inductor current measured in the application circuit by increasing output current until output voltage drops by 10%. Note 9: Min and Max limits are guaranteed by design, test or statistical analysis. Typical numbers are not guaranteed, but do represent the most likely norm. Note 10: The parameters in the electrical characteristic table are tested at VIN = 3.6V unless otherwise specified. For performance over the input voltage range refer to datasheet curves. www.national.com 4 LM3674 Electrical Characteristics (Notes 2, 9, 10) Limits in standard typeface are for TJ = 25˚C. Limits in boldface type apply over the full operating junction temperature range (−30˚C ≤ TJ ≤ 125˚C). Unless otherwise noted, specifications apply to the LM3674 with VIN = EN = 3.6V (Continued) Note 11: Input voltage range recommended for ideal applications performance for the specified output voltages are given below VIN = 2.7V to 5.5V for 1.0V ≤ VOUT < 1.8V VIN = ( VOUT + VDROP OUT) to 5.5V for 1.8 ≤ VOUT≤ 3.3V Where VDROP OUT = ILOAD * (RDSON (P) + RINDUCTOR) Note 12: Feedback voltage specification for ADJ include the tolerances of the resistor divider network. ADJ configured to 1.5V output. Dissipation Rating Table θJA 250˚C/W (2 layer board) 130˚C/W (4 layer board) TA ≤ 25˚C (Power Rating) TA = 60˚C (Power Rating) TA = 85˚C (Power Rating) 400mW 770mW 260mW 500mW 160mW 310mW 5 www.national.com LM3674 Block Diagram 20167232 FIGURE 4. Simplified Functional Diagram www.national.com 6 LM3674 Typical Performance Characteristics Quiescent Current vs. Supply Voltage (FB = 0V, No Switching) (unless otherwise stated: VIN = 3.6V, VOUT = 1.5V, TA = 25˚C) IQ Shutdown vs. Temp 20167244 20167205 Feedback Bias Current vs. Temp Output Voltage vs. Supply Voltage 20167206 20167265 Output Voltage vs. Temperature Output Voltage vs. Output Current 20167298 20167266 7 www.national.com LM3674 Typical Performance Characteristics (unless otherwise stated: VIN = 3.6V, VOUT = 1.5V, TA = 25˚C) (Continued) Efficiency vs. Output Current (VOUT = 1.2V, L = 2.2uH, DCR = 200mΩ) RDSON vs. Temperature 20167210 20167267 Efficiency vs. Output Current (VOUT = 1.5V, L = 2.2uH, DCR = 200mΩ) Efficiency vs. Output Current (VOUT = 1.8V, L = 2.2uH, DCR = 200mΩ) 20167268 20167269 Efficiency vs. Output Current