600mA Miniature Step-Down DC-DC Converter

LM3677 3MHz, 600mA Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits March 2007 LM3677 3MHz, 600mA Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits General Description The LM3677 step-down DC-DC converter is optimized for powering ultra-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. The LM3677 is configured to four output voltages of 1.3V, 1.5V, 1.8V and 2.5V. The device offers superior features and performance for mobile phones and similar portable applications with complex power management systems. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During PWM mode operation, the device operates at a fixed-frequency of 3 MHz (typ). PWM mode drives loads from ~ 80mA to 600mA max. Hysteretic PFM mode extends the battery life by reducing the quiescent current to 16 µA (typ) during light load and standby operation. Internal synchronous rectification provides high efficiency. In shutdown mode (Enable pin pulled down), the device turns off and reduces battery consumption to 0.01 µA (typ). The LM3677 is available in a lead-free (NO PB) 5-bump micro SMD package. A switching frequency of 3 MHz (typ) allows use of tiny surface-mount components. Only three external surface-mount components, an inductor and two ceramic capacitors, are required. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 16 µA typical quiescent current 600 mA maximum load capability 3 MHz PWM fixed switching frequency (typ) Automatic PFM/PWM mode switching Available in 5-bump micro SMD package Internal synchronous rectification for high efficiency Internal soft start 0.01 µA typical shutdown current Operates from a single Li-Ion cell battery Only three tiny surface-mount external components required (solution size less than 20 mm2) ■ Current overload and Thermal shutdown protection Applications ■ ■ ■ ■ ■ ■ ■ Mobile phones PDAs MP3 players W-LAN Portable Instruments Digital still cameras Portable Hard disk drives Typical Application Circuit Efficiency vs. Output Current (VOUT = 1.8V) 30008401 FIGURE 1. Typical Application Circuit 30008487 © 2007 National Semiconductor Corporation 300084 www.national.com LM3677 Connection Diagram and Package Mark Information 5-Bump micro SMD Package NS Package Number TLA05FEA 30008444 FIGURE 2. 5 Bump Micro SMD Package Pin Descriptions Pin # A1 A3 C1 C3 B2 Name VIN GND EN FB SW Description Power supply input. Connect to the input filter capacitor (Figure 1). Ground pin. Enable pin. The device is in shutdown mode when voltage to this pin is <0.4V and enabled when >1.0V. Do not leave this pin floating. Feedback analog input. Connect directly to the output filter capacitor ( FIGURE 1). Switching node connection to the internal PFET switch and NFET synchronous rectifier. Ordering Information Order Number LM3677TL-1.3 LM3677TLX-1.3 LM3677TL-1.5 LM3677TLX-1.5 LM3677TL-1.8 LM3677TLX-1.8 LM3677TL-2.5 LM3677TLX-2.5 Spec NOPB NOPB NOPB NOPB NOPB NOPB NOPB NOPB Package Marking V X Y Z Supplied As 250 units, Tape-and-Reel 3000 units, Tape-and-Reel 250 units, Tape-and-Reel 3000 units, Tape-and-Reel 250 units, Tape-and-Reel 3000 units, Tape-and-Reel 250 units, Tape-and-Reel 3000 units, Tape-and-Reel Note: 1.2V, 1.6V, 2.8V and ADJ are coming soon. www.national.com 2 LM3677 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. VIN Pin: Voltage to GND FB, SW, EN Pin: Continuous Power Dissipation (Note 3) Junction Temperature (TJ-MAX) Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec.) −0.2V to 6.0V (GND−0.2V) to (VIN + 0.2V) Internally Limited +125°C −65°C to +150°C 260°C ESD Rating (Note 4) Human Body Model: All Pins Machine Model: All Pins 2.0 kV 200V (Note 1), (Note 2) Operating Ratings Input Voltage Range 2.7V to 5.5V Recommended Load Current 0mA to 600 mA Junction Temperature (TJ) Range −30°C to +125°C Ambient Temperature (TA) Range (Note −30°C to +85°C 5) Thermal Properties Junction-to-Ambient Thermal Resistance (θJA) (Note 6) 85°C/W Electrical Characteristics (Note 2), (Note 8), (Note 9) Limits in standard typeface are for TJ = TA = 25°C. Limits in boldface type apply over the operating ambient temperature range (−30°C ≤ TA ≤ +85°C). Unless otherwise noted, specifications apply to the LM3677 with VIN = EN = 3.6V. Symbol VIN VFB VREF ISHDN IQ RDSON (P) RDSON (N) ILIM VIH VIL IEN FOSC Parameter Input Voltage Feedback Voltage 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 2.5 0.01 3 EN = 0V No load, device is not switching VIN= VGS= 3.6V, ISW= 100mA VIN= VGS= 3.6V, ISW= -100mA Open Loop(Note 7) 1085 1.0 0.4 1 3.5 PWM mode Condition Min 2.7 -2.5 0.5 0.01 16 350 150 1220 1 35 450 250 1375 Typ Max 5.5 +2.5 Units V % V µA µA mΩ mΩ mA V V µA MHz Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component 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: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ= 150°C (typ.) and disengages at TJ= 130°C (typ.). Note 4: 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 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 − (θJAx PD-MAX). Refer to Dissipation rating 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 85 °C/W is based on measurement results using a 4 layer board as per JEDEC standards. Note 7: 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 8: 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 9: The parameters in the electrical characteristic table are tested under open loop conditions at VIN= 3.6V unless otherwise specified. For performance over the input voltage range and closed loop condition, refer to the datasheet curves. 3 www.national.com LM3677 Dissipation Rating Table θJA 85°C/W (4-layer board) TA≤ 25°C Power Rating 1176 mW TA= 60°C Power Rating 765 mW TA= 85°C Power Rating 470 mW www.national.com 4 LM3677 Block Diagram 30008418 FIGURE 3. Simplified Functional Diagram 5 www.national.com LM3677 Typical Performance Characteristics LM3677TL, Circuit of Figure 1, VIN = 3.6V, VOUT = 1.8V, TA = 25°C, unless otherwise noted. Quiescent Supply Current vs. Supply Voltage (Switching) Shutdown Current vs. Temp 30008482 30008481 Switching Frequency vs. Temperature RDS(ON) vs. Temperature 30008483 30008451 Open/Closed Loop Current Limit vs. Temperature Output Voltage vs. Supply Voltage (VOUT = 1.8V) 30008449 30008484 www.national.com 6 LM3677 Output Voltage vs. Supply Voltage (VOUT = 2.5V) Output Voltage vs. Temperature (VOUT = 1.3V) 30008438 30008468 Output Voltage vs. Temperature (VOUT = 1.8V) Output Voltage vs. Temperature (VOUT = 2.5V) 30008485 30008469 Output Voltage vs. Output Current (VOUT = 1.8V) Output Voltage vs. Output Current (VOUT = 2.5V) 30008486 30008437 7 www.national.com LM3677 Efficiency vs. Output Current (VOUT = 1.3V) Efficiency vs. Output Current (VOUT = 1.8V) 30008441 30008487 Efficiency vs. Output Current (VOUT = 2.5V) Output Current vs. Input Voltage at Mode Change Point (VOUT = 1.3V) 30008432 30008435 Output Current vs. Input Voltage at Mode Change Point (VOUT = 1.8V) Output Current vs. Input Voltage at Mode Change Point (VOUT = 2.5V) 30008488 30008436 www.national.com 8 LM3677 Line Transient Response VOUT = 1.3V (PWM Mode) Line Transient Response VOUT = 1.8V (PWM Mode) 30008433 30008477 Line Transient Response VOUT = 1.8V (PWM Mode) Line Transient Response VOUT = 2.5V (PWM Mode) 30008478 30008439 Load Transient Response (VOUT = 1.3V) (PFM Mode 1mA to 50mA) Load Transient Response (VOUT = 1.3V) (PFM Mode 50mA to 1mA) 30008493 30008494 9 www.national.com LM3677 Load Transient Response (VOUT = 1.8V) (PFM Mode 1mA to 50m