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SC4215A
Very Low Input /Very Low Dropout 2 Amp Regulator With Enable
POWER MANAGEMENT Features
Input Voltage as low as 1.4V 400mV dropout @ 2A Adjustable output from 0.5V to 3.8V Over current and over temperature protection Enable pin 10A quiescent current in shutdown Full industrial temperature range Available in SOIC-8-EDP Lead-free package, fully WEEE and RoHS compliant
Description
The SC4215A 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 1.4V, with output voltage programmable as low as 0.5V. The SC4215A features ultra low dropout, ideal for applications where Vout is very close to Vin. Additionally, the SC4215A has an enable pin to further reduce power dissipation while shutdown. The SC4215A provides excellent regulation over variations in line, load and temperature. The SC4215A is available in the SOIC-8-EDP (Exposed Die Pad) package. The output voltage can be set via an external divider or to xed settings of 0.5V and 1.2V depending on how the FB pin is con gured.
Applications
Telecom/Networking cards Motherboards/Peripheral cards Industrial applications Wireless infrastructure Set top boxes Medical equipment Notebook computers Battery powered systems
Typical Application Circuit
January 28, 2009
(c) 2009 Semtech Corporation
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SC4215A
Pin Con guration Ordering Information
Device
SC4215ASTRT(1)(2) SC4215AEVB
Package
SOIC-8-EDP Evaluation Board
Notes: (1) 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
SC4215A
Absolute Maximum Ratings
VIN, EN, VO, FB to GND (V) . . . . . . . . . . . . . . . . . . -0.3 to +7.0 Power Dissipation . . . . . . . . . . . . . . . . . . . . . Internally Limited ESD Protection Level (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
(1)
Recommended Operating Conditions
VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 < VIN < 6.0 Ambient Temperature Range (C) . . . . . . . . . -40 < TA < +105 Junction Temperature Range (C) . . . . . . . . . -40 < TJ < +125 Maximum Output Current (A) . . . . . . . . . . . . . . . . . . . . . . . . .2
Thermal Information
Thermal Resistance, Junction to Ambient(2) (C/W) . . . . 36 Thermal Resistance, Junction to Case(2) (C/W). . . . . . . . 5.5 Maximum Junction Temperature (C) . . . . . . . . . . . . . .+150 Storage Temperature Range (C) . . . . . . . . . . . . -65 to +150 Peak IR Re ow Temperature (10s to 30s) (C) . . . . . . +260
Exceeding the above speci cations may result in permanent damage to the device or device malfunction. Operation outside of the parameters speci ed in the Electrical Characteristics section is not recommended. NOTES: (1) Tested according to JEDEC standard JESD22-A114-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 JESD51 standards.
Electrical Characteristics
Unless speci ed: VEN = VIN, VFB = VO, VIN = 1.40V to 6.0V, IO = 10A to 2A, TA = 25 C. Values in bold apply over the full operating temperature range.
Parameter
VIN
Symbol
Conditions
Min
Typ
Max
Units
VIN = 3.3V, IO = 0A Quiescent Current IQ VIN = 6.0V, VEN =0V VO VIN= VO + 0.5V, IO = 10mA Output Voltage(1) (Fixed Voltage, VFB = 0) -2% VO VIN = 1.8V, IO = 0.8A, 0C TJ = TA 85C 1.40V VIN 6.0V, IO = 10mA Line Regulation(1) Load Regulation(1) REG (LINE) REG(LOAD) IO =10mA IO =10mA to 2A -3% 0.2 0.5 VO 10
3 50
mA A
+2% V +3% 0.4 1.5 %/V %
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SC4215A
Electrical Characteristics (continued)
Parameter Symbol
IO =1A 1.6V VIN 6.0V 1.4V VIN < 1.6V Dropout Voltage(1)(2) VDO IO =1.5A 1.6V VIN 6.0V 1.4V VIN < 1.6V IO = 2A 1.6V VIN 6.0V Minimum Load Current(3)(4) Current Limit(4) Feedback 0.495 Reference Voltage(1) VREF VIN = 3.3V, VFB = VOUT , IO =10mA 0.490 Feedback Pin Current(4) Feedback Pin Threshold(5) EN Enable Pin Current IEN VIH Enable Pin Threshold VIL Over Temperature Protection High Trip Level Hysteresis THI THYST 160 10
O
Conditions
1.4V VIN < 1.6V
Min
Typ
90
Max
400 200
Units
200
500 mV 300
300
600 400 10 A A
IO ICL 2.1 3
4.4
0.505 0.5 0.510 80 200 0.15 nA V V
IADJ V TH(FB)
VFB = VREF 0.05
0.10
VEN = 0V, VIN =3.3V 1.6 VIN=3.3V
1.5
10
A
V 0.4
C C
O
Notes: (1) Low duty cycle pulse testing with Kelvin connections required. (2) VDO = VIN -VO when VO decreases by 1.5% of its nominal output voltage. (3) Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this requirement. (4) Guaranteed by design. (5) When VFB exceeds this threshold, the "Sense Select" switch disconnects the internal feedback chain from the error ampli er and connects VFB instead.
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SC4215A
Typical Characteristics
5
SC4215A
Pin Descriptions
Pin #
2
Pin Name
EN
Pin Function
Enable Input. Pulling this pin below 0.4V turns the regulator o , 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 = 1.4V. A large bulk capacitance should be placed closely to this pin to ensure that the input supply does not sag below 1.4V. 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 10uF capacitor should be placed directly at this pin. When this pin is grounded, an internal resistor divider sets the output voltage to 1.2V. If 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 1): 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 1, 4, 5
GND NC THERMAL PAD
Block Diagram
6
SC4215A
Applications Information (continued)
Introduction The SC4215A 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 10F/A (output load) should be closely placed to the input supply pin of the SC4215A to ensure that Vin does not sag below 1.4V. 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 10F/A (output load), along with a 0.1F 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 SC4215A 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 0.1F 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 to GND, an internal resistor divider will regulate the output voltage to 1.2V. If the FB pin is connected directly to the VO pin, the output voltage will be regulated to the 0.5V internal reference. External voltage selection resistors: The use of 1% resistors, and designing for a current ow 10A is recommended to ensure a well regulated output (thus R2 50k). A suitable value for R2 can be chosen in the range of 1k to 50k. R1 can then be calculated from.
R1 = R 2
(VO - VREF )
VREF
The highest output voltage achievable with external resistors is 4V. An attempt to set a higher voltage may result in VFB(TH) not being exceeded which will force the device into the 1.2V output mode. The SC4215H does not have this limitation and is recommended for applications requiring VO above 3.8V. Enable: Pulling this pin below 0.4V turns the regulator o , 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 < 1.9V are required. For applications with higher voltages than 1.9V, EN pin could be left open or connected to VIN. Thermal Considerations The power dissipation in the SC4215A 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 specied in the Thermal Information section on page 3.
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SC4215A
Outline Drawing -- SOIC-8-EDP-2
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SC4215A
Land Pattern -- SOIC-8-EDP-2
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com
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