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SC4215
Very Low Input /Very Low Dropout 2 Amp Regulator With Enable
POWER MANAGEMENT Features

Description
The SC425 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 2 amperes. It operates with a Vin as low as .6V, with output voltage programmable as low as 0.8V. The SC425 features ultra low dropout, ideal for applications where Vout is very close to Vin. Additionally, the SC425 has an enable pin to further reduce power dissipation while shut down. The SC425 provides excellent regulation over variations in line, load and temperature. The SC425 is available in the SOIC-8-EDP (Exposed Die Pad) package. The output voltage can be set via an external divider or to fixed settings of 0.8V and 2.5V depending on how the ADJ pin is configured.
Input Voltage as low as .6V 500mV dropout @ 2A Adjustable output from 0.8V Over current and over temperature protection Enable pin 0A quiescent current in shutdown Full industrial temperature range Available in SOIC-8-EDP Pb-Free product. RoHS/WEEE and Halogen Free 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
October 8, 2009
(c) 2009 Semtech Corporation
SC4215
Pin Configuration Ordering Information
Device
SC425ISTRT()(2) SC425IEVB
Package
SOIC-8-EDP Evaluation Board
Notes: () Available in tape and reel only. A reel contains 2,500 devices. (2) Available in Pb-Free product only. RoHS/WEEE and Halogen Free compliant.
Marking Information
2
SC4215
Absolute Maximum Ratings
VIN, EN, VO, ADJ to GND (V) . . . . . . . . . . . . . . . . . -0. to +7.0 Power Dissipation . . . . . . . . . . . . . . . . . . . . . Internally Limited ESD Protection Level (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
()
Recommended Operating Conditions
VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 < VIN < 5.5 Ambient Temperature Range (C) . . . . . . . . . -40 < TA < +85 Junction Temperature Range (C) . . . . . . . . . -40 < TJ < +25 Maximum Output Current (A) . . . . . . . . . . . . . . . . . . . . . . . . .2
Thermal Information
Thermal Resistance, Junction to Ambient(2) (C/W) . . . . 6 Thermal Resistance, Junction to Case(2) (C/W). . . . . . . . 5.5 Maximum Junction Temperature (C) . . . . . . . . . . . . . .+50 Storage Temperature Range (C) . . . . . . . . . . . . -65 to +50 Peak IR Reflow Temperature (0s to 0s) (C) . . . . . . +260
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. NOTES: () Tested according to JEDEC standard JESD22-A4-B. (2) Calculated from package in still air, mounted to " x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD5 standards.
Electrical Characteristics
Unless specified: VEN = VIN, VIN = .6V to 5.5V, IO = 0A to 2A, TA = 25 C. Values in bold apply over the full operating temperature range.
Parameter
VIN
Symbol
Conditions
Min
Typ
Max
Units
Quiescent Current VO Output Voltage() (Fixed Voltage, VADJ = 0) Line Regulation() Load Regulation()
IQ
VIN = .V, IO = 0A VIN = 5.5V, VEN =0V
0.75 0
1.75 50
mA A
VO REG (LINE) REG(LOAD)
VIN= VO + 0.5V, IO = 0mA .60V VIN 5.5V, IO = 0mA IO =0mA IO =0mA to 2A
-2% -3% VO 0.2 0.5
+2% V +3% 0.4 1.0 %/V %
SC4215
Electrical Characteristics (continued)
Parameter Symbol Conditions
IO =A 200 Dropout Voltage()(2) VDO IO =.5A VIN =VO+ 0.5V VIN =VO+ 0.6V VIN =VO+ 0.5V 2.2 00
Min
Typ
90
Max
00 400 400
Units
mV 500 500 600 10 4.5 A A
IO = 2A Minimum Load Current()(4) Current Limit(4) ADJ IO ICL
0.792 Reference Voltage() VREF IADJ V TH(ADJ) VIN = .V, VFB = VOUT , IO =0mA VADJ = VREF 0.05 0.8 0.784 80 0.6
0.808 V 0.816 200 0.40 nA V
Adjust Pin Current(4) Adjust Pin Threshold(5) EN Enable Pin Current
IEN VIH VIL
VEN = 0V, VIN =.V 1.6 VIN=.V
.5
10
A
Enable Pin Threshold Over Temperature Protection High Trip Level Hysteresis
V 0.4
THI THYST
60 0
O
C C
O
Notes: () Low duty cycle pulse testing with Kelvin connections required. (2) VDO = VIN -VO when VO decreases by .5% of its nominal output voltage. () Required to maintain regulation. Voltage set resistors R and R2 are usually utilized to meet this requirement. Adjustable mode 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.
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SC4215
Typical Characteristics
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SC4215
Pin Descriptions
Pin #
2
Pin Name
EN
Pin Function
Enable Input. Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction 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 = .6V. A large bulk capacitance should be placed closely to this pin to ensure that the input supply does not sag below .6V. Also a minimum of 4.7uF ceramic capacitor should be placed directly at this pin. The pin is the power output of the device. A minimum of 0uF capacitor should be placed directly at this pin. When this pin is grounded, an internal resistor divider sets the output voltage to 2.5V. If connected to the Vo pin, the output voltage will be set at 0.8V. If external feedback resistors are used, the output voltage will be determined by the resistor ratio (See Application Circuits on page ): Reference ground. The GND pin and the exposed die pad must be connected together at the IC pin. No Connection. Pad for heatsinking purposes. Connect to ground plane using multiple vias.
VIN
6
VO
7
ADJ
8 , 4, 5
GND NC THERMAL PAD
Block Diagram
6
SC4215
Applications Information (continued)
Introduction The SC425 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. Component Selection Input capacitor: A large bulk capacitance 0F/A (output load) should be closely placed to the input supply pin of the SC425 to ensure that Vin does not sag below .4V. Also a minimum of 4.7F 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 load transients is reduced, improving load transient response. Additional capacitance may be added if required by the application. Output capacitor: A minimum bulk capacitance of 0F/A (output load), 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 SC425 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. Internal voltage selection: By connecting the ADJ pin to GND, an internal resistor divider will regulate the output voltage to 2.5V. If the ADJ pin is connected directly to the VO pin, the output voltage will be regulated to the 0.8V internal reference. 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
7
50k). A suitable value for R2 can be chosen in the range of k to 50k. 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 SC425 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 .
SC4215
Outline Drawing -- SOIC-8-EDP-3
8
SC4215
Land Pattern -- SOIC-8-EDP-3
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 902 Phone: (805) 498-2 Fax: (805) 498-804 www.semtech.com
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