LM39100 [HTC]
1A Low-Voltage Low-Dropout Regulator; 1A低压低压降稳压器
| 型号： | LM39100 |
| 厂家： | 
HTC KOREA TAEJIN TECHNOLOGY CO. |
| 描述： | 1A Low-Voltage Low-Dropout Regulator |
| 文件： | 总9页 (文件大小：326K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
SOT-223
FEATURES
•Fixed and adjustable output voltages to 1.24V
•410mV typical dropout at 1A
Ideal for 3.0V to 2.5V conversion
Ideal for 2.5V to 1.8V or 1.5V conversion
•1A minimum guaranteed output current
•1% initial accuracy
LM39100-X.X Fixed
SOP-8
•Low ground current
•Current limiting and thermal shutdown
•Reversed-battery protection
•Reversed-leakage protection
•Fast transient response
•Low-profile SOT-223 package
PIN DESCRIPTION
CMOS-compatible control input.
Logic high = enable, logic
APPLICATIONS
Enable
•LDO linear regulator for PC add-in cards
•PowerPC™ power supplies
(Input)
Logic low or open = shutdown
Supply (Input)
IN
•High-efficiency linear power supplies
•SMPS post regulator
OUT
FLG
Regulator Output
Flag (Output): Open-collector error flag output.
Adjustment Input: Feedback input.
Connect to resitive voltage-divider network
Connect to resitive voltage-divider network
Ground
•Multimedia and PC processor supplies
•Battery chargers
ADJ
•Low-voltage microcontrollers and digital logic
GND
ORDERING INFORMATION
Device
LM39100- X.X
LM39101-X.X
LM39102-Adj
Marking
Package
SOT-223
SOP-8
LM39100-X.X
LM39101-X.X
LM39102-Adj
SOP-8
* X.X = Fixed Vout = 1.5V, 1.8V, 2.5V, 3.3V, 5.0V
DESCRIPTION
The LM39100, LM39101, and LM39102 are 1A low-dropout linear voltage regulators that provide low-
voltage,high-current output from an extremely small package.
The LM39100/1/2 offers extremely low dropout (typically 410mVat 1A) and low ground current (typically
12mA at 1A).
The LM39100 is a fixed output regulator offered in theSOT-223 package. The LM39101 and LM39102 are
fixedand adjustable regulators, respectively, in a thermally en-hanced power 8-lead SOP (small outline
package).
The LM39100/1/2 is ideal for PC add-in cards that need toconvert from standard 5V to 3.3V, 3.3V to 2.5V
or 2.5V to1.8V. A guaranteed maximum dropout voltage of 630mV overall operating conditions allows the
LM39100/1/2 to provide2.5V from a supply as low as 3.13V and 1.8V from a supplyas low as 2.43V.
The LM39100/1/2 is fully protected with over current limiting,thermal shutdown, and reversed-battery
protection. Fixed voltages of 5.0V, 3.3V, 2.5V,1.8V and 1.5V are available on LM39100/1 with adjustable
output voltages to 1.24V on LM39102.
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
Typical Application Circuit
Absolute Maximum Ratings (Note 1)
Supply Voltage (VIN)
–20V to +20V
+20V
–65°C to +150°C
260°C
Enable Voltage (VEN)
Storage Temperature (TS)
Lead Temperature (soldering, 5 sec)
ESD, Note 3
Operating Ratings (Note 2)
Supply Voltage (VIN)
+2.25V to +16V
+16V
Note 4
Enable Voltage (VEN)
Maximum Power Dissipation (PD(max))
Junction Temperature (TJ)
Package Thermal Resistance
SOT-223 (θJC)
–40°C to +125°C
15°C/W
20°C/W
SOP-8 (θJC)
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
Block Diagram
LM39100 Fixed (1.5V,1.8V,2.5V,3.3V,5.0V)
LM39100 Fixed with Flag and Enable
LM39102 Adjustable
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
TYPICAL PERFORMANCE CHARACTERISTICS
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
APPLICATION INFORMATION
The LM39100/1/2 is a high-performance low-dropout voltage regulator suitable for moderate to high-current
voltage regulator applications. Its 630mV dropout voltage at full loadand over temperature makes it especially
valuable in battery-powered systems and as high-efficiency noise filters in post-regulator applications. Unlike older
NPN-pass transistor de-signs, where the minimum dropout voltage is limited by thebase-to-emitter voltage drop
and collector-to-emitter satura-tion voltage, dropout performance of the PNP output of these devices is limited only
by the low VCE saturation voltage.A trade-off for the low dropout voltage is a varying base drive requirement.
The LM39100/1/2 regulator is fully protected from damage due to fault conditions. Linear current limiting is
provided.Output current during overload conditions is constant. Thermal shutdown disables the device when the die
temperature exceeds the maximum safe operating temperature. Tran-sient protection allows device (and load)
survival even when the input voltage spikes above and below nominal. The output structure of these regulators allows
voltages in excess of the desired output voltage to be applied without reverse current flow.
Output Capacitor
The LM39100/1/2 requires an output capacitor to maintain stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The LM39100/1/2 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor to maintain stability. When the output capacitor is 10µF
orgreater, the output capacitor should have an ESR less than 2Ω. This will improve transient response as well as
promote stability. Ultra-low-ESR capacitors (<100mΩ), such as ce-ramic chip capacitors, may promote instability.
These very low ESR levels may cause an oscillation and/or underdamped transient response. A low-ESR solid
tantalum capacitor works extremely well and provides good transient response and stability over temperature.
Aluminum electrolytics can also be used, as long as the ESR of the capacitor is <2Ω.The value of the output
capacitor can be increased without limit. Higher capacitance values help to improve transient response and ripple
rejection and reduce output noise.
Input Capacitor
An input capacitor of 1µF or greater is recommended whenthe device is more than 4 inches away from the bulk ac
supply capacitance or when the supply is a battery. Small, surfacemount, ceramic chip capacitors can be used for
bypassing. Larger values will help to improve ripple rejection by bypassing the input to the regulator, further
improving the integrity of the output voltage.
Error Flag
The LM39101 features an error flag (FLG), which monitors the output voltage and signals an error condition when this
voltage drops 5% below its expected value. The error flag isan open-collector output that pulls low under fault
conditions and may sink up to 10mA. Low output voltage signifies anumber of possible problems, including an
overcurrent fault(the device is in current limit) or low input voltage. The flag output is inoperative during
overtemperature conditions. Apull-up resistor from FLG to either VIN or VOUT is required for proper operation. For
information regarding the minimum and maximum values of pull-up resistance, refer to the graph in the typical
characteristics section of the data sheet.
Enable Input
The LM39101 and LM39102 versions feature an active-high enable input (EN) that allows on-off control of the
regulator. Current drain reduces to “zero” when the device is shutdown, with only micro amperes of leakage current.
The EN input has TTL/CMOS compatible thresholds for simple logic interfacing. EN may be directly tied to VIN and
pulled upto the maximum supply voltage
Transient Response and 3.3V to 2.5V or 2.5V to 1.8V Conversion
The LM39100/1/2 has excellent transient response to varia-tions in input voltage and load current. The device has
been designed to respond quickly to load current variations and input voltage variations. Large output capacitors are
not required to obtain this performance. A standard 10µF output capacitor, preferably tantalum, is all that is required.
Larger values help to improve performance even further.
By virtue of its low-dropout voltage, this device does not saturate into dropout as readily as similar NPN-based de-
signs. When converting from 3.3V to 2.5V or 2.5V to 1.8V, the NPN based regulators are already operating in
dropout, withtypical dropout requirements of 1.2V or greater. To convertdown to 2.5V or 1.8V without operating in
dropout, NPN-based regulators require an input voltage of 3.7V at the veryleast. The LM39100 regulator will provide
excellent perfor-mance with an input as low as 3.0V or 2.5V respectively. This gives the PNP based regulators a
distinct advantage overolder, NPN based linear regulators.
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
Minimum Load Current
The LM39100/1/2 regulator is specified between finite loads.If the output current is too small, leakage currents
dominate and the output voltage rises. A 10mA minimum load current is necessary for proper regulation.
Adjustable Regulator Design
The LM39102 allows programming the output voltage any-where between 1.24V and the 16V maximum operating
rating of the family. Two resistors are used. Resistors can be quite large, up to 1MΩ, because of the very high input
impedance and low bias current of the sense comparator: The resistor values are calculated by : R1=R2(Vout/1.240-
1)
Where VO is the desired output voltage. Figure 1 shows component definition. Applications with widely varying load
currents may scale the resistors to draw the minimum load current required for proper operation (see below).
Power SOP-8 Thermal Characteristics
One of the secrets of the LM39101/2’s performance is its power SO-8 package featuring half the thermal resistance
of a standard SO-8 package. Lower thermal resistance means more output current or higher input voltage for a given
package size.Lower thermal resistance is achieved by joining the four ground leads with the die attach paddle to
create a single-piece electrical and thermal conductor. This concept hasbeen used by MOSFET manufacturers for
years, proving very reliable and cost effective for the user.Thermal resistance consists of two main elements, θ
JC(junction-to-case thermal resistance) and θCA (case-to-ambient thermal resistance). See Figure2. θJC is the
resistance from the die to the leads of the package. θCA is the resistance from the leads to the ambient air and it
includes θCS (case-to-sink thermal resistance) and θSA (sink-to-ambient thermal resistance).Using the power SOP-
8 reduces the θJC dramatically and allows the user to reduce θCA. The total thermal resistance,θJA (junction-to-
ambient thermal resistance) is the limiting factor in calculating the maximum power dissipation capabil-ity of the
device. Typically, the power SOP-8 has a θJC of20°C/W, this is significantly lower than the standard SOP-8 which is
typically 75°C/W. θCA is reduced because pins 5 through 8 can now be soldered directly to a ground plane which
significantly reduces the case-to-sink thermal resis-tance and sink to ambient thermal resistance.Low-dropout linear
regulators from HTC are rated to amaximum junction temperature of 125°C. It is important not to exceed this
maximum junction temperature during operation of the device. To prevent this maximum junction temperature from
being exceeded, the appropriate ground plane heatsink must be used.
Figure3 shows copper area versus power dissipation with each trace corresponding to a different temperature rise
above ambient.From these curves, the minimum area of copper necessary for the part to operate safely can be
determined. The maxi-mum allow able temperature rise must be calculated to deter-mine operation along which
curve.
∆T = TJ(max) – TA(max)
TJ(max) = 125°C
TA(max) = maximum ambient operating temperature
For example, the maximum ambient temperature is 50°C, the∆T is determined as follows:
∆T = 125°C – 50°C
∆T = 75°C
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1A Low-Voltage Low-Dropout Regulator
LM39100/39101/39102
Using Figure3, the minimum amount of required copper can be determined based on the required power
dissipation.Power dissipation in a linear regulator is calculated as fol-lows:
PD = (VIN – VOUT) IOUT + VIN·IGND
If we use a 2.5V output device and a 3.3V input at an output current of 1A, then our power dissipation is as follows:
PD = (3.3V – 2.5V) × 1A + 3.3V × 11mA
PD = 800mW + 36mW
PD = 836mW
From Figure3, the minimum amount of copper required too perate this application at a ∆T of 75°C is 160mm2.
Quick Method
Determine the power dissipation requirements for the design along with the maximum ambient temperature at which
the device will be operated. Refer to Figure4, which shows safe operating curves for three different ambient
temperatures:25°C, 50°C and 85°C. From these curves, the minimum amount of copper can be determined by
knowing the maxi-mum power dissipation required. If the maximum ambient temperature is 50°C and the power
dissipation is as above,836mW, the curve in Figure5 shows that the required area of copper is 160㎟.The θJA of this
package is ideally 63°C/W, but it will vary depending upon the availability of copper ground plane to which it is
attached.
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