EC3202S E-CMOS | Alldatasheet
Document overview
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Technical content
Features
2A output current Current mode operation High efficiency up to 95% Shutdown current < 1µA 2.5V to 5.5V supply voltage Over temperature protection Constant frequency operation Full duty ratio, 0 – 100% in dropout RoHS Compliant and Lead (Pb) Free
Applications
Cellular phones PDAs and smart phones MP3 players Digital still cameras Slim-type DVD Wireless and DSL card Microprocessors and DSP core supplies Portable instruments Pin Assignments FB SW GND EN Vin Top View TSOT23-5L GNDEN SW Top View TDFN 2x2-6L NC Vin FB1
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter Pin Description TSOT23-5L TDFN 2x2-6L Symbol Description 1 2 EN Enable control input pin. 2 5 GND Ground pin. 3 4 SW Power switch output. 4 3 Vin Main supply pin. --- 1 NC No connected. 5 6 FB Feedback pin. Vout=0.6×(1+R1/R2). Add optional C1 to speed up transient response. Typical Application Circuit, Adjustable Output Voltage Vout = VFB × (1 + R1 /R2) with R1 = 300k for typical application, and C1 should be in the range between 10pF and 47pF for component selection.
Ordering Information
Part Number Package Marking Marking Information EC3202SNT2R TSOT23-5L 08LDD 1. L：Lot No 2. DD：Date Code
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter Absolute Maximum Ratings (Note 1) Operating Temperature Range ……...… –40°C to +85°C Storage Temperature Range …………... –65°C to +150°C Lead Temperature (Soldering 10s) …………...…. +260°C 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 Thermal Characteristics (Note 2) TSOT23-5L: TDFN 2x2-6L: Recommended Operating Conditions (Note 3) Junction Temperature Range…………… –40°C to +125°C Ambient Temperature Range …………… –40°C to +85°C Block Diagram PWM Logic Oscillator Reference Vin Zero-current comparator DCC Current Sense Amplifier UG LG SW GND PWM Comparator Clock 0.6V FB EN Error Amplifier Slop Comp
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter
Electrical Characteristics
(Vin = 5V, Vout= 1.8V, L = 2.2uH, Cout = 10uF, TA = 25° C, unless otherwise specified) PARAMETER Symbol TEST CONDITIONS MIN TYP MAX UNIT Supply Voltage Vin 2.5 5.5 V Output Voltage Line Regulation ∆Vout Vin = 2.5V to 5.5V −3 3 %V Output Voltage Load Regulation VLR −3 3 % Reference Voltage VREF For adjustable Vout 0.588 0.6 0.612 V Output Range (Adjustable Voltage) Vout Vin = 2.5V to 5.5V −3 +3 % Shutdown Current IS VEN = 0V 0.1 1 µA Quiescent Current IQ VEN = Vin, VFB = VREF × 1.1 No Switching 100 µA SW Leakage Current ILEAK VEN = 0V, VSW = 0V or Vin −1 1 µA PMOSFET On Resistance* RDSONP ISW = 100mA 110 mΩ NMOSFET On Resistance* RDSONN ISW = −100mA 95 mΩ PMOSFET Current Limit* ILIM Duty cycle = 100% Current Pulse Width < 1ms 3 A Oscillator Frequency FOSC 1.2 1.5 1.8 MHz Thermal Shutdown Threshold* TS 160 °C EN High Level Input Voltage VENH −40°C ≤ TA ≤ 85°C 1.5 V EN Low Level Input Voltage VENL −40°C ≤ TA ≤ 85°C 0.4 V EN Input Current IEN VEN = 0V to Vin −1 1 µA * Guaranteed by design not for test. Note 1: Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of th e device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2: θJA is measured in the natural convect ion at TA = 25° C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Pin 2 of TSOT23-5 packages is the case position for θJC measurement. Measured at the exposed pad of the package. Note 3: The device is not guaranteed to function outside its operating conditions.
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter Typical Characteristics Startup (Vin=5.0V, Vout=1.8V,Iload=2A) Shutdown (Vin=5.0V, Vout=1.8V,Iload=2A) Vin 5V/div Vout 1V/div IL 1A/div 50us/div Vin 5V/div Vout 1V/div IL 1A/div 10us/div Output Ripple (Vin=5.0V, Vout=1.8V,Iload=2A) Load Transient (Vin=5.0V, Vout=1.8V,Iload=0.2A~2A) Vout(AC) 10mv/div IL 1A/div 500ns/div Vout(AC) 50mv/div IL 2A/div 200us/div Soft Start Iload=2A Short Protection/Current limit (Vin=5.0V, Vout=1.8V,open to short) Vout 1V/div IL 1A/div 20us/div Vout 1V/div IL 1A/div 200us/div
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter FUNCTIONAL DESCRIPTION Overview The EC3202S is a constant frequency current mode PWM step down converter. EC3202S is optimized for low voltage, Li -ion battery, powered applications where high efficiency and small size are critical. The device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates an external Schottky diode. EC3202S can achieve 100% duty cycle. The duty cycle D of a step down converter is defined as: D = TON × FOSC × 100% ≈ Vin Vout × 100% Where TON is the main switch on time, FOSC is the oscillator frequency (1. 5MHz), Vout is the output voltage and Vin is the input voltage. Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle -by-cycle current limit for superior load and line response and protection of the internal main switch and sync hronous rectifier. EC3202S switches at a constant frequency (1.5MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltag e. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. When the main switch is off , the synchronous rectifier will be turned on immediately and stay on until either the next cycle starts or the inductor current drops to zero. The device skips pulses to improve efficiency at light load. Dropout Operation EC3202S allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to th e P MOSFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. Short Circuit Protection The EC3202S has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the P MOSFET current limit. The frequency will return to the normal values once the short circuit condition is removed and the Vout reaches regulated voltage. Maximum Load Current The EC3202S can operate down to 2.5V input voltage; however the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub -harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases.
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter
APPLICATION INFORMATION
A 2.2μH to 4.7μH is recommended for gen eral used. The value of inductor depends on the operating frequency. Higher frequency allows smaller inductor and capacitor but increases internal switching loss. Two inductor parameters should be considered, current rating and DCR. The inductor with the l owest DCR is chosen for the highest efficiency. The inductor value can be calculated as: L ≥ [VOUT/(f × ΔIL)](1 – VOUT/VIN) ΔIL: inductor ripple current, which is defined as: ΔIL = VOUT[(1 – VOUT/VIN)/(L × f)] (General Setting) ≈ α × IO-MAX (α = 0.2~0.4) The inductor should be rated for the maximum output current (I O-MAX) plus the inductor ripple current (ΔIL) to avoid saturation. The maximum inductor current (IL-MAX) is given by: IL-MAX = IO-MAX +ΔIL/2 Capacitor Selection The small size of ceramic capacitors are ideal for EC3202S applications. X5R and X7R types are recommended because they retain their capacitance over wider voltage and temperature ranges than other types, such as Y5V or Z5U. A 4.7μF input capacitor and a 10μF output capacitor are sufficient for most EC3202S applications. When selecting an output capacitor, consider the output ripple voltage and the ripple current. The ESR of capacitor is a major factor to the output ripple. For the best performance , a low ESR output capacitor is required. The ripple voltage is given by: ΔVO = ΔIL [ESR + 1/(8 × f × C O)] Output Voltage Programming (Adjustable Voltage Version) The output voltage of EC3202S is set by the resistor divider according to the following formula: VOUT = VFB × (1 + R1/R2) R1 is the upper resistor of the voltage divider. For transient response reasons, a small feed -forward capacitor (CF) is required in parallel to the upper feedback resistor, and33pF is recommended. Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, V OUT will be shifted immediately by an amount equal to (Δ ILOAD × ESR), where ESR is the e ffective series resistance of C OUT. ΔILOAD will also begin to charge or discharge C OUT, which generates a feedback error signal. Then the regulator loop will act to return VOUT to its steady state value. During this recovery time, V OUT can be monitored for overshoot or ringing that will indicate the stability problem. The discharged bypass capacitors are effectively put in parallel with C OUT, causing a rapidly drop in V OUT. No regulator can deliver enough current to prevent this problem if the load switch resistance is low and it is driven quickly. The only solution is to limit the rise time of the switch drive, so that the load rise time will be limited to approximately (25 × CLOAD).
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter
Package Information
Symbol Dimensions in mm Dimensions in Inch Min Max Min Max A 0.700 1.100 0.028 0.043 A1 0.000 0.130 0.000 0.005 B 1.500 1.700 0.059 0.067 b 0.300 0.559 0.012 0.022 C 2.500 3.100 0.098 0.122 D 2.800 3.100 0.110 0.122 e 0.950 BSC 0.037 BSC H 0.080 0.200 0.003 0.008 L 0.200 0.800 0.008 0.031 A C D B A H L e b
EC3202S 2A, 1.5MHz, Synchronous Step Down DC/DC Converter SYMBOLS DIMENSION (MM) DIMENSION (INCH) MIN NOM MAX MIN NOM MAX e 0.650 0.026 1 2 SEE DETAIL A DETAIL A D E L e b A