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SC4215H
Very Low Input /Very Low Dropout 2 Amp Regulator With Enable
POWER MANAGEMENT Features

Description
The SC425H 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 .4V, with output voltage programmable as low as 0.5V. The SC425H features ultra low dropout, ideal for applications where Vout is very close to Vin. Additionally, the SC425H has an enable pin to further reduce power dissipation while shutdown. The SC425H provides excellent regulation over variations in line, load and temperature. The SC425H 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 .4V 400mV dropout @ 2A Adjustable output from 0.5V Over current and over temperature protection Enable pin 0A 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
(c) 2009 Semtech Corporation
SC4215H
Pin Configuration Ordering Information
Device
SC425HSETRT()(2) SC425HEVB
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
SC4215H
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) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 < VIN < 6.0 Ambient Temperature Range (C) . . . . . . . . . -40 < TA < +05 Junction Temperature Range (C) . . . . . . . . . -40 < TJ < +25 Maximum Output Current (A) . . . . . . . . . . . . . . . . . . . . . . . . .2
Thermal Information
Thermal Resistance, Junction to Ambient(2) (C/W) . . . . 36 Thermal Resistance, Junc 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 30s) (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 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD5 standards.
Electrical Characteristics
Unless specified: VEN = VIN, VFB = VO, VIN = .40V to 6.0V, 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
IQ
VIN = 3.3V, IO = 0A VIN = 6.0V, VEN =0V 0
3 50
mA A
VIN= VO + 0.5V, IO = 0mA Output Voltage() (Fixed Voltage, VFB = VO) VO VIN = .8V, IO = 0.8A, 0C TJ = TA 85C .40V VIN 6.0V, IO = 0mA Line Regulation() Load Regulation() REG (LINE) REG(LOAD) IO =0mA IO =0mA to 2A
-2% VO -3% 0.2 0.5
+2% V +3% 0.4 1.5 %/V %
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SC4215H
Electrical Characteristics (continued)
Parameter Symbol
IO =A
Conditions
.4V VIN < .6V .6V VIN 6.0V .4V VIN < .6V .6V VIN 6.0V .4V VIN < .6V .6V VIN 6.0V
Min
Typ
90
Max
400 200
Units
200
500 mV 300 600 400 10 A A
Dropout Voltage()(2)
VDO
IO =.5A
300
IO = 2A Minimum Load Current(3)(4) Current Limit(4) Feedback IO ICL
2.1
3
4.4
0.495 Reference Voltage() VREF IADJ VIN = 3.3V, VFB = VOUT , IO =0mA VFB = VREF 0.5 0.490 80
0.505 V 0.510 200 nA
Feedback Pin Current(4) EN Enable Pin Current
IEN VIH VIL
VEN = 0V, VIN =3.3V 1.6 VIN=3.3V
.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 with VIN = VO +0.8V. (3) Required to maintain regulation. Voltage set resistors R and R2 are usually utilized to meet this requirement. (4) Guaranteed by design.
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SC4215H
Typical Characteristics
5
SC4215H
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 6.0V. Minimum VIN = .4V. A large bulk capacitance should be placed closely to this pin to ensure that the input supply does not sag below .4V. 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 connected to the Vo pin, the output voltage will be set at 0.5V. 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.
3
VIN
6
VO
7
FB
8 , 4, 5
GND NC THERMAL PAD
Block Diagram
6
SC4215H
Applications Information (continued)
Introduction The SC425H 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. The SC425H is especially recommended for applications where VO>3.8V, for lower output voltage requirements the SC425A can be considered. Component Selection Input capacitor: A large bulk capacitance 0F/A (output load) should be closely placed to the input supply pin of the SC425H 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 SC425H 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 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 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 SC425H 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.
SC4215H
Outline Drawing -- SOIC-8-EDP-2
8
SC4215H
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
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