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| SC4217 POWER MANAGEMENT Features Very Low Input /Very Low Dropout 3 Amp Regulator With Enable Description The SC427 is a 3A, high performance LDO designed for use in applications requiring very low input voltage and very low dropout voltage. It operates with an input voltage as low as .8V and a programmable output voltage from .24V. The SC427 features ultra- low dropout, ideal for applications where VOUT is very close to V IN . Additionally, the SC427 has an enable pin to further reduce power dissipation while shut down. The SC427 provides excellent regulation over line, load and temperature. The SC427 is available in a TO263-5 package and is fully WEEE and RoHS compliant. Input voltage range from .8V to 5.5V Typical 300mV dropout @ 3A Adjustable output from .24V Over-current and over-temperature protection Enable pin 0A shutdown current Full industrial temperature range TO263-5 package, fully WEEE and RoHS compliant Applications Telecom/networking equipment Motherboards/peripheral cards Industrial equipment Wireless infrastructure Set-top boxes Medical equipment Typical Application Circuit EN 1 2 SC4217 EN VIN GND ADJ VO 4 VO VIN 3 C1 5 R1 C2 R2 0 0 October 29, 2007 SC4217 Pin Configuration Ordering Information Device SC427MTRT()(2) Package TO263-5 Evaluation Board TOP VIEW TAB SC427EVB Notes: ) Available in tape and reel only. A reel contains 800 devices. 2) Device is WEEE and RoHS compliant. 1 2 3 4 5 (TO263-5L) Marking Information SC4217 Eyww xxxxxxxxx TOP MARK CHAR ROWS 9/9/9 3 Marking for TO263 5 Lead Package: Eyww = Datecode (Example: E752) xxxxxxxxx = Semtech Lot # (Example:EA0180101) 2 SC4217 Absolute Maximum Ratings VIN, VO, ADJ to GND ......................................................6V EN ......................................................... -0.3V to VIN+0.3V Lead Temperature (Soldering) 0s ................................. 300C ESD Protection Level ................................................... 2kV Recommended Operating Conditions VIN Range................................................... .8V to 5.5V Maximum Output Current............................................. 3A Operating Ambient Temperature Range .................. -40 to +85C Operating Junction Temperature Range............... -40 to +25C Storage Temperature Range .............................. -65 to +50C Thermal Information Thermal Resistance, junction to case J()JC.................. 7C/W Thermal Resistance, junction to ambient JJA............... 30C/W Note () 2 square inch of FR-4, double sided, oz. minimum copper weight. Other Notes: Tested according to JEDEC standard JESD22-A4-B. Calculated from package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD5 standards. Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. Electrical Characteristics ) Unless otherwise noted, VEN = VIN. VIN = .8V to 5.5V, VIN = VO+0.5V, and IO = 0A to 3A. 2) Values in bold apply over the full operating temperature range. Parameter VIN Quiescent Current VO Output Voltage() Line Regulation() Load Regulation() Symbol Conditions Min Typ Max Units IQ VIN = 3.3V VIN = 5.5V, VEN = 0V 0.75 0 1.75 50 mA A VO REG(LINE) REG(LOAD) VIN = VO + 0.5V -2% -3% +2% +3% 0.2 0.5 90 0.4 1.0 300 400 200 400 500 300 500 600 V %/V % IO = 0mA IO = 0mA to 3A IO = A Dropout Voltage(, 2) VD IO = .5A IO = 3A, VIN = VO + 0.5V mV Dropout Voltage(, 2) Minimum Load Current(3) Current Limit VD IO ICL mV A A VIN = VO +0.5V 3.3 4.5 10 6.75 3 SC4217 Electrical Characteristics (continued) Parameter ADJ Reference Voltage() Adjust Pin Current(4) Adjust Pin Threshold EN Enable Pin Current Enable Pin Theshold Over Temperature Protection High Trip Level Hysteresis THI THYST 60 0 C IEN VIH VIL VEN = 0V, VIN = 3.3V VIN = 3.3V VIN = 3.3V 1.6 0.4 .5 10 A V (5) Symbol Conditions Min Typ Max Units VREF IADJ V TH(ADJ) VIN = 3.3V, VADJ = VOUT, IO = 0mA .227 1.215 .24 80 .252 1.265 200 0.40 V nA V VADJ = VREF 0.05 0.6 Notes: ) Low duty cycle pulse testing with Kelvin connections required. 2) Defined as the input to output differential at which the output voltage drops to .5% below the value measured at a differential of 0.8V. 3) Required to maintain regulation. Voltage set resistors R and R2 are usually utilized to meet this requirement. Adjustable versions only. 4) Guaranteed by design. 5) When VADJ exceeds this threshold, the "Sense Select" switch disconnects the internal feedback chain from the error amplifier and connects VADJ instead. 4 SC4217 Pin Descriptions Pin # Pin Name EN Pin Function Enable input. Pulling this pin below 0.4V turns off the regulator reducing the quiescent current to a franction of its operating value. The device will be enabled if this pin is left open. Connect to VIN if not being used. Input voltage. For regulation at full load, the input to this pin must be between (VO+0.5V) and 5.5V. Minimum VIN = .8V. A large bulk capacitance should be placed closey to this pin to ensure that the input supply does not sag below .8V. A minimum of 4.7F ceramic capacitors should be placed directly at this pin. Reference ground. The GND pin and the exposed die pad must be connected together at the IC pin. The pin is the power output of the device. A minimum of 0F capactor should be placed directly at this pin. Use external feedback resistors to program the output voltage. See application circuit on page . VO= [(R2+R)*.24V]/R2. The ADJ pin cannot be tied directly either to VO pin or to GND pin. Thermal pad should be connected to PCB ground plane for thermal and electrical purposes. 2 VIN 3 4 GND VO 5 ADJ T THERMAL PAD Block Diagram RSense VIN VPump Current Limit Reference VDD 1.5uA EN 1.24V REF Thermal Shutdown ADJ VO GND VOUT VIN Reverse Voltage Shutdown 5 SC4217 Typical Characteristics ) Unless otherwise noted, typical values are taken under the conditions: TAMBIENT=25C, VIN=3.3V, VO=2.5V, IO=2A, CIN=COUT=0.mF(Ceramic)+0mF(Tantalum) Dropout Voltage vs Output Current 350 300 250 200 150 100 50 0 0 1 2 Output Current (A) 25C Dropout Voltage vs Temperature 400 350 300 250 200 150 100 50 IOUT =1A IOUT =3A 3 4 -50 -25 0 25 50 75 100 Temperature ( C ) ADJ Pin Leakage Current vs Temperature 90 88 86 1.0 VADJ =1.24V Quiescent Current vs Input Voltage 2.0 1.5 TAMBIENT = 85 C 84 82 80 -50 -25 0 25 50 75 100 Temperature ( C ) TAMBIENT = 25 C 0.5 0.0 3 3.5 4 4.5 5 5.5 6 6.5 Input Voltage ( V ) Enable Voltage High vs Temperature 1.75 1.50 1.25 V IN =3.3V V IN =5.5V Enable Voltage Low vs Temperature 1.50 V IN =5.5V 1.25 V IN =3.3V 1.00 1.00 0.75 0.50 -50 -25 0 25 50 75 100 Temperature ( C ) V IN =1.8V 0.75 V IN =1.8V 0.50 -50 -25 0 25 50 75 100 Temperature ( C ) 6 SC4217 Typical Characteristics ) Unless otherwise noted, typical values are taken under the conditions: TAMBIENT=25C, VIN=3.3V, VO=2.5V, IO=2A, CIN=COUT=0.mF(Ceramic)+0mF(Tantalum) Soft start performance Load transient test Input voltage Output Voltage Output voltage EN pin voltage Output Current 7 SC4217 Applications Information Introduction The SC427 is intended for applications where high current capability and very low dropout voltage are required. It provides a very simple, low cost solution that uses very little PCB real estate. Additional features include an enable pin to allow for a very low power consumption standby mode, and a fully adjustable output. Thermal Considerations The power dissipation in the SC427 is approximately equal to the product of the output current and the input to output voltage differential: PD (VIN VOUT) IO The absolute worst-case dissipation is given by: PD (VIN(MAX) VOUT(MIN)) IO(MAX) VIN(MAX) IQ(MAX) Component Selection Input Capacitor A minimum of 4.7F ceramic or tantalum 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, bulk capacitance of about 0F may be added closely to the input supply pin of the SC427 to ensure that Vin does not sag, improving load transient response. Output Capacitor A minimum bulk capacitance of 0F, along with a 0.F 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 SC427 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.F ceramic capacitors be placed from IN to GND and OUT to GND as close to the device pins as possible. External Voltage Selection Resistors The use of % resistors, and designing for a current flow 0A is recommended to ensure a well regulated output (thus R2 50k). For a typical scenario, VIN = 3.3V 5%, VOUT = 2.8V and IO = .5A, therefore: VIN(MAX) = 3.465V, VOUT(MIN) = 2.744V and IQ(MAX) = .75mA, Thus PD(MAX) = .09W. Using this figure, and assuming TA(MAX) = 70C, we can calculate the maximum thermal impedance allowable to maintain TJ 50C: RTH(J A)(MAX) (TJ(MAX) TA(MAX)) PD(MAX) (150 70) 1.09 73.4 C/W This should be achievable for the TO263-5 package using pcb copper area to aid in conducting the heat away, such as one square inch of copper connected to the exposed die pad of the device. Internal ground/power planes and air flow will also assist in removing heat. For higher ambient temperatures it may be necessary to use additional copper area. Enable Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction of its operating value. 8 SC4217 Typical Application Circuits C1 1uF R1 10k 1 VIN=3.3V 2 3 C5 10uF (Tantalum) C4 0.1uF(Ceramic) AGND SC4217 EN VIN GND ADJ VO 4 R2 10.2k 5 C2 0.1uF(Ceramic) R3 10k C3 10uF (Tantalum) VO=2.5V GND 0 PGND GND 0 0 Figure 1: Application circuit with 3.3V input and 2.5V output 9 SC4217 Outline Drawing -- TO263-5 A E E/2 DIM L1 A A1 b c c1 D D1 E E1 H e L L1 N 0 01 aaa 0 DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX .190 4.06 4.83 .010 0.00 0.25 .039 0.51 0.99 .029 0.38 0.74 .065 1.14 1.65 .380 8.28 9.65 6.86 .420 9.65 10.67 6.22 .625 14.61 15.88 .067 BSC 1.70 BSC .070 .110 1.78 2.79 .066 1.68 5 5 15 15 0 8 0 8 .010 0.25 .160 .000 .020 .015 .045 .326 .270 .380 .245 .575 D 12345 H e bXN aaa BA A SEATING PLANE B A1 c1 SIDE VIEW SEE DETAIL A PLATED COPPER HEAT SPREADER D1 (L1) E1 DETAIL c L NOTES: 1. 2. CONTROLLING DIMENSIONS ARE IN INCHES (ANGLES IN DEGREES). DIMENSIONS "D" AND "E" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. A 01 0 SC4217 Land Pattern -- TO263-5 H DIM DIMENSIONS INCHES MILLIMETERS .125 .420 .350 .067 .042 .140 .615 3.17 10.67 8.89 1.70 1.07 3.56 15.62 K Z G H K P X Y Z G Y P NOTES: 1. X THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 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 |
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