SC4211STRT [SEMTECH]
Very Low Input /Very Low Dropout 1 Amp Regulator With Enable; 极低的输入/非常低压差1安培稳压器启用
| 型号： | SC4211STRT |
| 厂家： | 
SEMTECH CORPORATION |
| 描述： | Very Low Input /Very Low Dropout 1 Amp Regulator With Enable |
| 文件： | 总8页 (文件大小：202K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SC4211
Very Low Input /Very Low Dropout
1 Amp Regulator With Enable
POWER MANAGEMENT
Description
Features
The SC4211 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 1
amp. It operates with a Vin as low as 1.4V, with output
voltage programmable as low as 0.5V. The SC4211 fea-
tures ultra low dropout, ideal for applications where Vout
is very close to Vin. Additionally, the SC4211 has an en-
able pin to further reduce power dissipation while shut-
down. The SC4211 provides excellent regulation over varia-
tions in line, load and temperature.
Input Voltage as low as 1.4V
250mV dropout @ 1A
Adjustable output from 0.5V to 3.3V
Over current and over temperature protection
Enable pin
10µA quiescent current in shutdown
Low reverse leakage (output to input)
Full industrial temperature range
Available in SOIC-8EDP package
The SC4211 is available in the SOIC-8EDP (Exposed Die
Pad) package. The output voltage can be set via an exter-
nal divider or to 0.5V depending on how the FB pin is con-
figured.
Applications
Telecom/Networking cards
Motherboards/Peripheral cards
Industrial Applications
Wireless infrastructure
Set top boxes
Medical equipment
Notebook computers
Battery powered systems
Typical Application Circuits
SC4211
4
3
2
1
5
NC
VIN
EN
NC
NC
6
VIN
VO
FB
GND
VO
7
8
ENABLE
0.5(R1+ R2)
R1
R2
VO
=
Volts
R2
U1
C1
C2
SC4211
4
5
NC
VIN
EN
NC
NC
VO
3
2
1
6
7
8
VIN
VO = 0.5V
ENABLE
FB
GND
U1
C1
C2
Revision October 18, 2004
1
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SC4211
POWER MANAGEMENT
Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in
the Electrical Characteristics section is not implied.
Parameter
Symbol
Max
Units
V
Vin, EN, Vo, FB Absolute Voltage
Power Dissipation
7
PD
Internally Limited
W
Thermal Resistance Junction to Ambient
SOIC-8EDP(1)
36
°C/W
θJA
Thermal Resistance Junction to Case
SOIC-8EDP(1)
θJC
TA
5.5
-40 to +85
-40 to +150
-65 to +150
300
°C/W
°C
Operating Ambient Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
TJ
°C
TSTG
TLEAD
VESD
°C
Lead Temperature (Soldering) 10 Sec.
ESD Rating (Human Body Model)
°C
2
kV
Note: (1) 2 square inch of FR-4, double sided, 1 oz. minimum copper weight.
Electrical Characteristics
Unless specified: V = VIN, V = VO, VIN = 1.40V to 5.5V, VIN = (VO + 0.5V) to 5.5V and IO = 1mA to 1A.
Values in bold applEyNover theFfBull operating temperature range.
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
VIN
Supply Voltage Range
Quiescent Current
VIN
IQ
1.40
5.5
3
V
VIN = 3.3V, IOUT = 0A
VIN = 5.5V, VEN = 0V
mA
µA
10
VO
50
VO
Output Voltage(1)
(Internal Fixed Voltage)
Line Regulation(1)
VO
VIN = VO + 0.5V, IOUT = 10mA
Full IOUT , and VIN Range
-1.5%
+1.5%
+3%
1.0
V
-3%
REG(LINE)
VIN = (VO + 0.5V), VIN < 3.3V, IOUT = 10mA
VIN = (VO + 0.5V), VIN > 3.3V, IOUT = 10mA
VIN = (VO + 0.5V), IOUT = 10mA to 1A
IO = 10mA
0.25
0.5
%
%
1.5
Load Regulation(1)
Dropout Voltage(1)(2)
REG(LOAD)
VD
0.5
1.5
%
2.5
10
mV
20
IO = 500mA
90
200
300
mV
Notes:
(1)
(2)
Low duty cycle pulse testing with Kelvin connections required.
Defined as the input to output differential at which the output voltage drops to 1.5% below the value measured at a
differential of 0.5V.
(3)
(4)
Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this requirement.
Guaranteed by design.
2004 Semtech Corp.
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SC4211
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless specified: V = VIN, V = VO, VIN = 1.40V to 5.5V, VIN = (VO + 0.5V) to 5.5V and IO = 1mA to 1A.
Values in bold applEyNover theFfBull operating temperature range.
Parameter
Symbol
Test Conditions
Min
1.1
Typ
Max
Units
VO (Cont.)
Dropout Voltage(1)(2)
IO = 1A
200
400
500
1
mV
Minimum Load Current(3)
Current Limit(4)
IO
VIN = VO + 0.5V
mA
A
ICL
1.5
0.5
80
Feedback
Reference Voltage(1)
VREF
VIN = 3.3V, VFB = VOUT, IO = 10mA
Full IOUT , and VIN Range
VFB = VREF
0.495
0.505
0.515
200
V
0.485
Feedback Pin Current(4)
EN
IADJ
nA
Enable Pin Current
Enable Pin Threshold
IEN
VIH
VIL
VEN = 0V, VIN = 3.3V
VIN = 3.3V
1.5
10
µA
V
1.6
VIN = 3.3V
0.4
Over Temperature Protection
High Trip level
THI
160
10
°C
°C
Hysteresis
THYST
Notes:
(1)
(2)
Low duty cycle pulse testing with Kelvin connections required.
Defined as the input to output differential at which the output voltage drops to 1.5% below the value measured at a
differential of 0.5V.
(3)
(4)
Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this requirement.
Guaranteed by design.
2004 Semtech Corp.
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SC4211
POWER MANAGEMENT
Ordering Information
Part Number
SC4211STRT(1)(2)(3)
SC4211EVB
Package
SOIC-8EDP
Temp. Range (TA)
-40 to +85 OC
Evaluation Board
Note:
(1) Available voltage is : 0.5V or Output voltage can be adjusted using
external resistors, see Pin Descriptions.
(2) Only available in tape and reel packaging 2500 devices for the
SOIC-8EDP package.
(3) Lead free product.
Pin Configuration
Top View
Bottom View
GND
GND
FB
VO
NC
EN
VIN
NC
GND
FB
8
7
6
5
NC
EN
VIN
NC
1
2
3
4
Exposed
Die Pad
VO
NC
NC
SOIC-8EDP
SOIC-8EDP
Pin Descriptions
Pin Name Pin Description
FB
When this pin is 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 (See Application Circuits on page 1):
0.5(R1+ R2)
VO
=
Volts
R2
EN
GND
VIN
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.
Reference ground. Note: The GND pin and the exposed die pad must be connected together at the IC pin.
Use the exposed die pad on the device for heatsinking.
Input voltage. For regulation at full load, the input to this pin must be between (VO+ 0.5V) and 5.5V. 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.
VO
The pin is the power output of the device. A minimum of 10uF ceramic capacitor should be placed directly at
this pin.
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SC4211
POWER MANAGEMENT
Block Diagram
VIN
VOUT
Rsense
Vpump
-
+
FB
+
-
Vdd
0.5V Ref
EN
UVLO
GND
Thermal
Shutdown
Vout
Vin
+
-
Reverse Voltage
Shutdown
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SC4211
POWER MANAGEMENT
Applications Information
Introduction
Thermal Considerations
The SC4211 is intended for applications where high cur- The power dissipation in the SC4211 is approximately equal
rent capability and very low dropout voltage are required. to the product of the output current and the input to out-
It provides a very simple, low cost solution that uses very put voltage differential:
little PCB real estate. Additional features include an en-
able pin to allow for a very low power consumption standby
mode, and a fully adjustable output.
PD
≈ VIN − VOUT • IO
( )
The absolute worst-case dissipation is given by:
Component Selection
PD(MAX)
=
(
VIN
− VOUT
)
• IO(MAX) + VIN
• IQ(MAX)
(MAX)
(MAX)
(MIN)
Input capacitor: A large bulk capacitance of about 100uF
should be closely placed to the input supply pin of the
SC4211 to ensure that Vin does not sag below 1.4V. 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 load transients is reduced,
improving load transient response. Additional capacitance
may be added if required by the application.
For a typical scenario, VIN = 3.3V ± 5%, VOUT = 2.8V and
IO = 1A, therefore:
VIN(MAX) = 3.465V, VOUT(MIN) = 2.744V and IQ(MAX) = 1.75mA,
Thus PD(MAX) = .722W.
Using this figure, and assuming TA(MAX) = 70°C, we can cal-
culate the maximum thermal impedance allowable to main-
tain TJ ≤ 150°C:
Output capacitor: a minimum bulk capacitance of 10µF,
along with a 0.1µF 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 SC4211 is extremely tolerant of out-
put capacitor ESR values and thus will also work
comfortably with tantalum output capacitors.
(
T
J(MAX) −TA(MAX)
)
(
=
150−70
)
.722
RTH(J−A)(MAX)
=
=110°C/W
PD(MAX)
This should be achievable for the SOIC-8EDP package
using PCB copper area to aid in conducting the heat away,
such as one square inch of copper connected to the ground
pins 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 cop-
per area.
Noise immunity: in very electrically noisy environments, it
is recommended that 0.1µF 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 1%
resistors, and designing for a current flow ≥ 10µA is
recommended to ensure a well regulated output (thus R2
≤ 120kΩ).
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SC4211
POWER MANAGEMENT
Outline Drawing - SOIC-8EDP
Land Pattern - SOIC-8EDP
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SC4211
POWER MANAGEMENT
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805)498-2111 FAX (805)498-3804
2004 Semtech Corp.
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