LM2990-5.0MW8 [TI]
LM2990QML Negative Low Dropout Regulator; LM2990QML负低压差稳压器
| 型号： | LM2990-5.0MW8 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | LM2990QML Negative Low Dropout Regulator |
| 文件： | 总12页 (文件大小：456K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM2990QML
LM2990QML Negative Low Dropout Regulator
Literature Number: SNVS391
December 8, 2010
LM2990QML
Negative Low Dropout Regulator
General Description
Features
The LM2990 is a three-terminal, low dropout, 1 ampere neg-
ative voltage regulator available with a fixed output voltage of
−5V.
5% output accuracy over entire operating range
■
■
■
■
■
■
■
Output current in excess of 1A
Dropout voltage typically 0.6V at 1A load
Low quiescent current
The LM2990 uses new circuit design techniques to provide
low dropout and low quiescent current. The dropout voltage
at 1A load current is typically 0.6V and a guaranteed worst-
case maximum of 1V over the entire operating temperature
range. The quiescent current is typically 1 mA with 1A load
current and an input-output voltage differential greater than
3V. A unique circuit design of the internal bias supply limits
the quiescent current to only 9 mA (typical) when the regulator
is in the dropout mode (VOUT − VIN ≤ 3V). Output voltage ac-
curacy is guaranteed to ±5% over load, and temperature
extremes.
Internal short circuit current limit
Internal thermal shutdown with hysteresis
Functional complement to the LM2940 series
Applications
Post switcher regulator
■
■
■
Local, on-card, regulation
Battery operated equipment
The LM2990 is short-circuit proof, and thermal shutdown in-
cludes hysteresis to enhance the reliability of the device when
overloaded for an extended period of time.
Ordering Information
NS Part Number
LM2990-5.0 MD8
LM2990-5.0 MW8
SMD Part Number
NS Package Number
(Note 1)
Package Description
Bare Die
(Note 1)
Bare Die
Note 1: FOR ADDITIONAL DIE INFORMATION, PLEASE VISIT THE HI REL WEB SITE AT: www.national.com/analog/space/level_die
16-Lead Ceramic Dual-in-Line Package
20158633
Top View
See NS Package Number J16A
© 2010 National Semiconductor Corporation
201586
www.national.com
Equivalent Schematic
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2
Absolute Maximum Ratings (Note 2)
Input Voltage
Power Dissipation (Note 3)
Junction Temperature (TJmax
Storage Temperature
−26V to +0.3V
Internally Limited
150°C
)
−65°C ≤ TA ≤ +150°C
Thermal Resistance
ꢀꢀθJA
Ceramic Dip (Still Air @ 0.5°C/W)
Ceramic Dip (500LF/Min Air flow @ 0.5°C/W)
ꢀꢀθJC
75°C/W
35°C/W
Ceramic Dip (Note 4)
5°C/W
Package Weight
Ceramic Dip
Lead Temperature (Soldering, 10 sec.)
ESD Susceptibility (Note 5)
TBD
260°C
2KV
Recommended Operating Conditions (Note 2)
Temperature Range (TJ)
−55°C ≤ TJ ≤ +125°C
Maximum Input Voltage (Operational)
−26V
Quality Conformance Inspection
Mil-Std-883, Method 5005 - Group A
Subgroup
Description
Static tests at
Temp (°C)
1
2
+25
+125
-55
Static tests at
3
Static tests at
4
Dynamic tests at
Dynamic tests at
Dynamic tests at
Functional tests at
Functional tests at
Functional tests at
Switching tests at
Switching tests at
Switching tests at
Settling time at
Settling time at
Settling time at
+25
+125
-55
5
6
7
+25
+125
-55
8A
8B
9
+25
+125
-55
10
11
12
13
14
+25
+125
-55
3
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LM2990-5.0 Electrical Characteristics
DC Parameters
The following conditions apply, unless otherwise specified. VIN = −5V + VO Nom, IO = 1A, CO = 47µF (Note 6)
Sub-
groups
Symbol
VO
VRLine
VRLoad
Parameter
Output Voltage
Conditions
Notes
Min Max
Unit
-5.10 -4.90
-5.25 -4.75
V
V
1
5mA ≤ IO ≤ 1A
2, 3
IO = 5mA,
Line Regulation
Load Regulation
40
mV
1, 2, 3
VO Nom -1V > VIN > -26V
70
100
0.3
mV
mV
V
1
50mA ≤ IO ≤ 1A
2, 3
1, 2, 3
IO = 0.1A, ΔVO ≤ 100mV
IO = 1A, ΔVO ≤ 100mV
VDO
Dropout Voltage
1.0
V
1, 2, 3
5.0
mA
mA
mA
A
1
2, 3
1, 2, 3
1
IO ≤ 1A
IQ
10
50
Quiescent Current
IO = 1A, VIN = VO Nom
1.5
IOS
Short Circuit Current
Maximum Output Current
Ripple Rejection
RL = 1Ω
(Note 7)
(Note 7)
1.3
A
2, 3
1
IMax
RR
VOn
1.5
A
VRipple = 1VRMS, FRipple = 1KHz,
IO = 5mA
50
dB
µV
1
Output Noise Voltage
10Hz-100Khz, IO = 5mA
750
1, 2, 3
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (package
junction to ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature is PDmax = (TJmax - TA)/
θ
JA or the number given in the Absolute Maximum Ratings, whichever is lower.
Note 4: The package material for these devices allows much improved heat transfer over our standard ceramic packages. In order to take full advantage of this
improved heat transfer, heat sinking must be provided between the package base (directly beneath the die), and either metal traces on, or thermal vias through,
the printed circuit board. Without this additional heat sinking, device power dissipation must be calculated using θJA, rather than θJC, thermal resistance. It must
not be assumed that the device leads will provide substantial heat transfer out of the package, since the thermal resistance of the leadframe material is very poor,
relative to the material of the package base. The stated θJC thermal resistance is for the package material only, and does not account for the additional thermal
resistance between the package base and the printed circuit board. The user must determine the value of the additional thermal resistance and must combine
this with the stated value for the package, to calculate the total allowed power dissipation for the device.
Note 5: Human body model, 1.5 kΩ in series with 100 pF.
Note 6: VO Nom is the nominal (typical) regulator output voltage, −5V.
Note 7: The −5V version, tested with a lower input voltage, does not reach the foldback current limit and therefore conducts a higher short circuit current level.
If the LM2990 output is pulled above ground, the maximum allowed current sunk back into the LM2990 is 1.5A.
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4
Load Regulation: The change in output voltage for a change
in load current at constant chip temperature.
Definition of Terms
Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction
in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at (VO + 5V)
input, dropout voltage is dependent upon load current and
junction temperature.
Long Term Stability: Output voltage stability under acceller-
ated life-test conditions after 1000 hours with maximum rated
voltage and junction temperature.
Output Noise Voltage: The RMS AC voltage at the output,
with constant load and no input ripple, measured over a spec-
ified frequency range.
Input Voltage: The DC voltage applied to the input terminals
with respect to ground.
Quiescent Current: That part of the positive input current
that does not contribute to the positive load current. The reg-
ulator ground lead current.
Input-Output Differential: The voltage difference between
the unregulated input voltage and the regulated output volt-
age for which the regulator will operate.
Ripple Rejection: The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
Line Regulation: The change in output voltage for a change
in the input voltage. The measurement is made under condi-
tions of low dissipation or by using pulse techniques such that
the average chip temperature is not significantly affected.
Temperature Stability of VO: The percentage change in
output voltage for a thermal variation from room temperature
to either temperature extreme.
Typical Performance Characteristics
Dropout Voltage
Normalized Output Voltage
20158614
20158615
LM2990-5.0
Quiescent Current
LM2990-5.0
Low Voltage Behavior
20158616
20158619
5
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LM2990-5.0
Line Transient Response
LM2990-5.0
Load Transient Response
20158620
20158621
LM2990-5.0
Ripple Rejection
LM2990-5.0
Output Impedance
20158625
20158626
Maximum Output Current
Maximum Output Current
20158627
20158630
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6
Typical Applications
20158601
*Required if the regulator is located further than 6 inches from the power supply filter capacitors. A 1 μF solid tantalum or a 10 μF aluminum electrolytic capacitor
is recommended.
**Required for stability. Must be at least a 10 μF aluminum electrolytic or a 1 μF solid tantalum to maintain stability. May be increased without bound to maintain
regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and should be less than
10Ω over the same operating temperature range as the regulator.
Post Regulator for an Isolated Switching Power Supply
20158605
The LM2940 is a positive 1A low dropout regulator; refer to
its datasheet for further information.
gin, creating oscillations (refer to the graph on the right). An
input capacitor, of at least 1 μF solid tantalum or 10 μF alu-
minum electrolytic, is also needed if the regulator is situated
more than 6″ from the input power supply filter.
Fixed Current Sink
FORCING THE OUTPUT POSITIVE
Due to an internal clamp circuit, the LM2990 can withstand
positive voltages on its output. If the voltage source pulling
the output positive is DC, the current must be limited to 1.5A.
A current over 1.5A fed back into the LM2990 could damage
the device. The LM2990 output can also withstand fast posi-
tive voltage transients up to 26V, without any current limiting
of the source. However, if the transients have a duration of
over 1 mS, the output should be clamped with a Schottky
diode to ground.
20158607
Adjustable Current Sink
Output Capacitor ESR
20158610
Application Hints
EXTERNAL CAPACITORS
The LM2990 regulator requires an output capacitor to main-
tain stability. The capacitor must be at least 10 μF aluminum
electrolytic or 1 μF solid tantalum. The output capacitor's ESR
must be less than 10Ω, or the zero added to the regulator
frequency response by the ESR could reduce the phase mar-
20158609
7
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Revision History
Released
Revision
Section
Changes
12/08/2010
A
New Release, Corporate format
MDS data sheet converted into Corp. data sheet
format. Data Sheet referencing Die NSID LM2990–
5.0 MD8 and MW8 only. Package products are Code
K no longer available. Archive the 3 MDS data sheets
MNLM2990-5.0-X Rev 0B1, MNLM2990-12-X Rev
0B0, and MNLM2990-15-X Rev 0B0.
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8
Physical Dimensions inches (millimeters) unless otherwise noted
16–Lead Ceramic Dual–in–Line Package
NS Package Number J16A
9
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