eorex (Preliminary) EP3102 150 KHz, 2A Asynchronous Step-down Converter Features Description • 3.3V, 5V, 12V and Adjustable Output Version • Adjustable Version Output Voltage Range, 1.23V to 37V +4% Max over Line and Load Condition • Input Voltage Range up to 40V • Output Load Current: 2A • 150 KHz Fixed Frequency Internal Oscillator • Voltage Mode Non-synchronous PWM Control • Thermal-shutdown and Current-limit Protection • ON/OFF Shutdown Control Input • Low Power Standby Mode • Built-in Switching Transistor on Chip • SOP-8L package The EP3102 is a monolithic integrated circuit that provide all the active functions for a step-down switching regulator, capable of driving a 2A load without additional transistor component. Requiring a minimum number of external component, the board space can be saved easily. The external shutdown function can be controlled by TTL logic level and then come into standby mode. The internal compensation makes feedback control have good line and load regulation without external design. Regarding protected function, thermal shutdown is to prevent over temperature operating from damage, and current limit is against over current operating of the output switch. The EP3102 operates at a switching frequency of 150KHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Other features include a guaranteed +4% tolerance on output voltage under specified input voltage and output load conditions, and +15% on the oscillator frequency. The output version included fixed 3.3V, 5V, 12V, and an adjustable type. The package is available in a standard 8-lead SOP8. Applications • Simple High-efficiency Step-down (Buck) Regulator • Efficient Pre-regulator for Linear Regulators • On-card Switching Regulators • Positive to Negative Converter • Battery Charger Typical Application Nov. 2006 www.eorex.com 1/10 eorex EP3102 Pin Assignment Ordering Information EP3102 - X X X Buck Regulator Package VOUT Packing S : SOP-8L Blank: Adj 33 = 3.3V 50 = 5.0V 12 = 12V R: Taping & Reel B: Bag Pin Description Pin Name Function 1 VIN This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. 2 SW Internal switch. The voltage at this pin switches between (+VIN-VSAT) and approximately-0.5V, with a duty cycle of approximately VOUT/VIN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept a minimum. 3 FB Senses the regulated output voltage to complete the feedback loop. 4 EN Low enable. Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 150uA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of 40V) shuts the regulator down. If this shutdown feature is not needed, the EN pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the ON condition. 5~8 GND Circuit ground. Nov. 2006 www.eorex.com 2/10 eorex EP3102 Absolute Maximum Rating (Note 1) Symbol VIN Item Input Supply Voltage V EN VFB VOUT VOP PD TOP TSTG EN Pin Input Voltage Feedback Pin Voltage Output Voltage to Ground Operating Voltage Power Dissipation Operating Temperature Range Storage Temperature Range Rating Units +45 V -0.3 ~ +25 V -0.3 ~ +25 -1 +4.5 ~+25 Internally Limited -40 ~ +125 -65 ~ +150 V V V W °C °C Electrical Characteristics (All Output Voltage Versions) (Note 2) Unless otherwise specified, VIN=12V for 3.3V, 5V, adjustable version and VIN=24V for the 12V version. ILOAD=0.2A Symbol IFB Parameter Feedback Bias Current FOSC Oscillator Frequency FSCP Oscillator Frequency of Short Circuit Protect VSAT Saturation Voltage DC ICL IL Max. Duty Cycle (ON) Min. Duty Cycle (OFF) Current Limit Output=0 Output=-1 IQ ISTBY Output Leakage Current Conditions Min. VFB=1.3V (Adjustable version only) 127 110 When current limit occurred and VFB<0.55V IOUT=1.5A no outside circuit VFB=0V force driver on VFB=0V force driver on VFB=12V force driver off Peak Current no outside circuit VFB=0V force driver on Typ. Max. Units -10 -50 -100 nA 150 173 173 KHz 30 70 KHz 1.25 1.4 1.5 100 0 2.4 2.8 No outside circuit VFB=12V fore driver off % 3.3 3.6 -200 VIN=24V -5 Quiescent Current VFB=12V force driver off 5 Standby Quiescent Current EN pin=5V VIN=24V Low (regulator ON) 70 V A µA mA 10 150 200 0.6 mA -0.01 µA -1 µA µA VIL VIH EN Pin Logic Input Threshold Voltage High (regulator OFF) IH EN Pin Logic Input Current VLOGIC=2.5V (OFF) IL EN Pin Input Current VLOGIC=0.5V (ON) -0.1 TS Over Temperature Shutdown Threshold TJ increasing TJ decreasing 175 150 °C °C θJC Thermal Resistance SOP-8L Junction to Case 15 °C/W θJA Thermal Resistance with Copper Area of Approximately 3in2 SOP-8L Junction to Ambient 70 °C/W Nov. 2006 2.0 1.3 V www.eorex.com 3/10 eorex EP3102 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2:100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. Electrical Characteristics (Continued) Symbol VFB η VOUT η VOUT η VOUT η Parameter Output Feedback EP3102-ADJ Conditions 5V<VIN<40V 0.2A<ILOAD<2A VOUT programmed for 3V Typ. Limit Units 1.235 1.193/1.18 1.267/1.28 V VMIN VMAX Efficiency VIN=12V, ILOAD=2A 75 Output Voltage 5.5V<VIN<40V 0.2A<ILOAD<2A 3.3 Efficiency VIN=12V, ILOAD=2A 75 Output Voltage 8V<VIN<40V 0.2A<ILOAD<2A 5 Efficiency VIN=12V, ILOAD=2A 80 Output Voltage 15V<VIN<40V 0.2A<ILOAD<2A 12 VIN=15V, ILOAD=2A 90 Efficiency EP3102-3.3V EP3102-5V EP3102-12V % 3.168/3.135 3.432/3.465 V VMIN VMAX % 4.8/4.75 5.2/5.25 V VMIN VMAX % 11.52/11.4 12.48/12.6 V VMIN VMAX % P.S. Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. Nov. 2006 www.eorex.com 4/10 Threshold Voltage (V) Supply Voltage (V) Saturation Voltage (V) Efficiency (%) Output Voltage (V) Output Voltage (V) eorex EP3102 Typical Performance Characteristics Nov. 2006 5/10 www.eorex.com eorex EP3102 Typical Performance Characteristics (Continued) Nov. 2006 www.eorex.com 6/10 eorex EP3102 Functional Block Diagram Applications Information (1) Fixed Type Circuit Nov. 2006 www.eorex.com 7/10 eorex EP3102 Applications Information (Continued) (2) Adjustable Type Circuit R2 R1 3 FB 1 12V DC Input CIN 330uF + VIN EP3102 SW L1 33uH 2 D1 Schottky Diode EN GND GND GND GND 4 5 6 7 8 ⎛ ⎝ VOUT= VFB × ⎜1 + 2.5V/2A Output Load Inductor + COUT 330uF R1 ⎞ ⎟ R2 ⎠ VFB=1.23V R2=1K ~ 3K (3) Delay Start Circuit Nov. 2006 www.eorex.com 8/10 eorex EP3102 Thermal Considerations The SOP-8 package needs a heat sink under most conditions. The size of the heat-sink depends on the input voltage, the output voltage, the load current and the ambient temperature. The EP3102 junction temperature rises above ambient temperature for a 2A load and different input and output voltages. The data for these curves was taken with the EP3102 operating as a buck switching regulator in an ambient temperature of 25°C (still air). These temperature increments are all approximate and are affected by many factors. Some of these factors include board size, shape, thickness, position, location, and even board temperature. Other factors are traced width, total printed circuit copper area, copper thickness, single or double-sided, multi-layer board and amount of solder on the board. Higher ambient temperatures require more heat sinking. For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (One exception is the out (switch) pin, which should not have large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the board, as well as whether the surrounding air is still or moving. Furthermore, some of these components such as the catch diode will add heat to the PC board and heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board. Nov. 2006 www.eorex.com 9/10 eorex EP3102 Package Description SOP-8L DIM MILLIMETERS INCHES MIN. NOM. MAX. MIN. NOM. MAX. A 1.40 1.60 1.75 0.055 0.063 0.069 A1 0.10 − 0.25 0.040 − 0.100 A2 1.30 1.45 1.50 0.051 0.057 0.059 B 0.33 0.41 0.51 0.013 0.016 0.020 C 0.19 0.20 0.25 0.0075 0.008 0.010 D 4.80 4.85 5.05 0.189 0.191 0.199 E 3.80 3.91 4.00 0.150 0.154 0.157 e − 1.27 − − 0.050 − H 5.79 5.99 6.20 0.228 0.236 0.244 L 0.38 0.71 1.27 0.015 0.028 0.050 y − − 0.10 − − 0.004 θ 0° − 8° 0° − 8° Nov. 2006 www.eorex.com 10/10