SC4216HEVB

SC4216H Very Low Input /Very Low Dropout 3 Amp Regulator With Enable POWER MANAGEMENT Features         Description The SC426H is a high performance positive voltage regulator designed for use in applications requiring very low input voltage and very low dropout voltage at up to 3 amperes. It operates with a Vin as low as .45V, with output voltage programmable as low as 0.5V. The SC426H features ultra low dropout, ideal for applications where Vout is very close to Vin. Additionally, the SC426H has an enable pin to further reduce power dissipation while shutdown. The SC426H provides excellent regulation over variations in line, load and temperature. The SC426H is available in the SOIC-8-EDP (Exposed Die Pad) package. The output voltage can be set via an external divider or to a fixed setting of 0.5V depending on how the FB pin is configured. Input Voltage as low as .45V 500mV dropout @ 3A Adjustable output from 0.5V Over current and over temperature protection Enable pin 0µA quiescent current in shutdown Full industrial temperature range Available in SOIC-8-EDP Lead-free package, fully WEEE and RoHS compliant Applications         Telecom/Networking cards Motherboards/Peripheral cards Industrial applications Wireless infrastructure Set top boxes Medical equipment Notebook computers Battery powered systems Typical Application Circuit February 3, 2009 © 2009 Semtech Corporation  SC4216H Pin Configuration Ordering Information Device SC426HSETRT()(2) SC426HEVB Package SOIC-8-EDP Evaluation Board Notes: () Available in tape and reel only. A reel contains 2,500 devices. (2) Available in lead-free package only. Device is WEEE and RoHS compliant. Marking Information 2 SC4216H Absolute Maximum Ratings VIN, EN, VO, FB to GND (V) . . . . . . . . . . . . . . . . . . -0.3 to +7.0 Power Dissipation . . . . . . . . . . . . . . . . . . . . . Internally Limited ESD Protection Level (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 () Recommended Operating Conditions VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 3.8V, for lower output voltage requirements the SC426 can be considered. Component Selection Input capacitor: A l arge bulk capacitance ≥ 0µF/A (output load) should be closely placed to the input supply pin of the SC426H to ensure that Vin does not sag below .45V. Also a minimum of 4.7µF ceramic capacitor is recommended to be placed directly next to the Vin pin. This allows for the device being some distance from any bulk capacitance on the rail. Additionally, input droop due to l oad transients is reduced, improving load transient response. Additional capacitance may be added if required by the application. Output capacitor: A minimum bulk capacitance of ≥ 0µF/A (output load), along with a 0.µF ceramic decoupling capacitor is recommended. Increasing the bulk capacitance will improve the overall transient response. The use of multiple lower value ceramic capacitors in parallel to achieve the desired bulk capacitance will not cause stability issues. Although designed for use with ceramic output capacitors, the SC426H is extremely tolerant of output capacitor ESR values and thus will also work comfortably with tantalum output capacitors. Noise immunity: In very electrically noisy environments, it is recommended that 0.µF ceramic capacitors be placed from IN to GND and OUT to GND as close to the device pins as possible. Internal voltage selection: By connecting the FB pin directly to the VO pin, the output voltage will be regulated to the 0.5V internal reference. External voltage selection resistors: The use of % resistors, and designing for a current flow ≥ 0µA is recommended to ensure a well regulated output (thus R2 7 ≤50kΩ). A suitable value for R2 can be chosen in the range of kΩ to 50kΩ. R can then be calculated from. R1 = R 2 ⋅ (VO − VREF ) VREF Enable: Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction of its operating value. A pull up resistor up to 400kOhms should be connected from this pin to the VIN pin in applications where supply voltages of Vin < .9V are required. For applications with higher voltages than .9V, EN pin could be left open or connected to VIN. Thermal Considerations The power dissipation in the SC426H is given by: PD ≈ IO ⋅ (VIN − VO ) The allowable power dissipation will be dependant on the thermal impedance achieved in the application. The derating curve below is valid for the thermal impedance specified in the Thermal Information section on page 3. SC4216H Outline Drawing — SOIC-8-EDP-2 8 SC4216H Land Pattern — SOIC-8-EDP-2 Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 9302 Phone: (805) 498-2 Fax: (805) 498-3804 www.semtech.com 9