1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

FEATURES SOT-223 PKG

 Fixed and adjustable output voltages to 1.24V
 470mV 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 SOP-8 PKG
 1% initial accuracy
 Low ground current
 Current limiting and thermal shutdown
 Reversed-battery protection
 Reversed-leakage protection TO-252 PKG
 Fast transient response
 Moisture Sensitivity Level 3

APPLICATION
 Battery Powered Equipments
ORDERING INFORMATION
 Motherboards and Graphic Cards
Device Package
 Microprocessor Power Supplies LM37100S-X.X SOT-233
 Peripheral Cards LM37101D-X.X
SOP-8
 High Efficiency Linear Regulators LM37102D
 Battery Chargers LM37101RS-X.X
TO-252
LM37102RS
X.X = Output Voltage = 1.5, 1.8, 2.5, 3.3, 5.0

DESCRIPTION
The LM37100/1/2 is 1A low-dropout linear voltage regulators that provide low-voltage, high-current output. The
LM37100/1/2 offers extremely low dropout (typically 470mV at 1A) and low ground current (typically 12mA at
1A). The LM37100/1 and LM37102 are fixed and adjustable regulators, respectively, in SOT-223, SOP-8 and
TO-252 Package.
The LM37100/1/2 is ideal for PC add-in cards that need to convert 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
LM37100/1/2 to provide2.5V from a supply as low as 3.13V and 1.8V from a supply as low as 2.43V. The
LM37100/1/2 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 LM37100/1 with adjustable output voltages
to 1.24V on LM37102.

Absolute Maximum Ratings (Note 1)

CHARACTERISTIC SYMBOL MIN. MAX. UNIT
Supply Voltage VIN - 0.3 + 20 V
Enable Voltage VEN - + 20 V
Output Voltage VOUT -0.3 VIN +0.3 V
Lead Temperature (Soldering, 5 sec) TSOL - 260 ℃
Storage Temperature Range TSTG -65 + 150 ℃

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102
Operating Ratings (Note 2)
CHARACTERISTIC SYMBOL MIN. MAX. UNIT

Supply Voltage VIN + 2.25 + 16 V

Enable Voltage VEN + 2.25 + 16 V

(Note 3)
PD(max-SOP-8) 0.77
(Note 3)
Maximum Power Dissipation PD(max-TO-252) 0.95 W
(Note 3)
PD(max-SOT-223) 0.73

Junction Temperature TJ -40 + 125 ℃

θJA-SOP-8 130 ℃/W

Package Thermal Resistance θJA-TO-252 105 ℃/W

θJA-SOT-223 137 ℃/W

Ordering Information
VOUT Package Order No. Description Supplied As Status

SOP-8 LM37101D-1.5 1A, Fixed, Enable Reel Contact us.

1.5V
TO-252 LM37101RS-1.5 1A, Fixed, Enable Reel Contact us.
SOP-8 LM37101D-1.8 1A, Fixed, Enable Reel Contact us.
1.8V
TO-252 LM37101RS-1.8 1A, Fixed, Enable Reel Contact us.
SOT-223 LM37100S-2.5 1A, Fixed Reel Active
2.5V SOP-8 LM37101D-2.5 1A, Fixed, Enable Reel Contact us.
TO-252 LM37101RS-2.5 1A, Fixed, Enable Reel Contact us.
SOP-8 LM37101D-3.3 1A, Fixed, Enable Reel Contact us.
3.3V
TO-252 LM37101RS-3.3 1A, Fixed, Enable Reel Contact us.
SOP-8 LM37101D-5.0 1A, Fixed, Enable Reel Contact us.
5.0V
TO-252 LM37101RS-5.0 1A, Fixed, Enable Reel Contact us.
SOP-8 LM37102D 1A, Adjustable, Enable Reel Active
ADJ
TO-252 LM37102RS 1A, Adjustable, Enable Reel Contact us.

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

LM 3710X

Output Voltage : 1.5V / 1.8V / 2.5V / 3.3V / 5.0V / Blank(ADJ Only)

S : SOT-223
Package Type D : SOP-8
RS : TO-252
37100 : Fixed Output
Root Name 37101 : Fixed Output
37102 : Adjustable Output
Product Code

PIN CONFIGURATION

3 VOUT 5 FLG/ADJ
EN 1 8 GND
4 VOUT
VIN 2 7 GND
2 GND (Tab) 3 GND (TAB)
VOUT 3 6 GND 2 VIN
1 VIN FLG/ADJ 4 5 GND 1 EN

SOT-223 SOP-8 TO-252 5L

PIN DESCRIPTION
TO-252 5L PKG SOP-8 PKG
Pin No.
Name Function Name Function
1 EN Chip Enable EN Chip Enable
2 VIN Input Supply VIN Input Supply
3 GND Ground VOUT Output Voltage
Error Flag Output
4 VOUT Output Voltage FLG / ADJ
or Output Adjust
5 FLG / ADJ Error Flag Output GND Ground
or Output Adjust
6/7/8 - - GND Ground

SOT-223-3L PKG
Pin No.
Name Function
1 VIN Input Supply
2 GND Ground
3 VOUT Output Voltage

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

TYPICAL APPLICATION

LM37100

3.3V IN OUT 2.5V

GND

2.5V / 1A Regulator

100k Error Flag

Output

LM37101
3.3V IN OUT 2.5V

Enable EN FLG
Shutdown GND

2.5V / 1A Regulator with Error Flag

LM37102
2.5V IN OUT 1.5V
R1
Enable EN ADJ
Shutdown GND R2

1.5V / 1A Adjustable Regulator

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102
ELECTRICAL CHARACTERISTICS
VIN= VOUT +1V; VEN = 2.25V; TJ = 25°C, bold values indicate -40°C ≤ TJ ≤ +125°C; unless noted
Symbol Parameters Condition Min. Typ. Max. Unit
10mA -1 1 %
VOUT Output Voltage
10mA ≤ IOUT ≤ 1A, VOUT+1V ≤ VIN ≤8V -2 2 %
Line Regulation IOUT=10mA, VOUT +1V ≤ VIN ≤ 16V 0.06 0.5 %

Load Regulation VIN= VOUT +1V, 10mA ≤ IOUT ≤ 1A 0.2 1 %

Output Voltage Temp.
ΔVOUT/ΔT (Note 4) 40 100 ppm/ °C
Coefficient
170 210 mV
IOUT=100mA, ΔVOUT = -1%
250 mV
IOUT=500mA, ΔVOUT = -1% 315 mV
(Note 5)
VDO Dropout Voltage
IOUT=750mA, ΔVOUT = -1% 390 500 mV
470 570 mV
IOUT=1A, ΔVOUT = -1%
630 mV
IOUT=100mA, VIN= VOUT+1V 700 μA
(Note 6)
IGND Ground Current IOUT=500mA, VIN= VOUT+1V 4 mA

IOUT=750mA, VIN= VOUT+1V 7 mA

IOUT(lim) Current Limit VOUT=0V, VIN=VOUT+1V 1.8 2.5 A

Enable Input
logic low (off) 0.8 V
VEN Enable Input Voltage
logic high (on) 2.25 V
1 15 30 μA
VEN=2.25V
75 μA
IEN Enable Input Current
2 μA
VEN=0.8V
4 μA
IOUT =10mA, VIN =VOUT +1V,
50 500
VEN =0V to VIN
Delay time to
IOUT =500mA, VIN =VOUT +1V,
TEN Nominal Output Voltage 250 2000 μs
(Note 7) VEN =0V to VIN
IOUT =1.0A, VIN =VOUT +1V,
350 3000
VEN =0V to VIN
Flag Output
Output Leakage 0.01 1 μA
IFLG (leak) VOH=16V
Current 2 μA
Output Low Voltage 240 300 mV
VFLG (do) (Note 8) VIN=0.9.VOUT NOMINAL, IOL=250μA
400 mV
Low Threshold % of VOUT 93 %

VFLG High Threshold % of VOUT 99.2 %

Hysteresis 1 %

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102
LM37102 Only
1.228 1.24 1.252 V
Reference Voltage
1.215 1.265 V
VREF
(Note 9)
1.203 1.277 V

Adjust Pin Bias 40 80 nA

IREF
Current 120 nA
Reference Voltage
ΔVREF/ΔT (Note 4) 20 ppm/ °C
Temp. Coefficient
Adjust Pin Bias Current
ΔIADJ/ΔT 0.1 99.2 nA/ °C
Temp. Coefficient

Note 1. Exceeding the absolute maximum ratings may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. PD (max)= (TJ (max) - TA) ÷ θJA, where θJA -junction-to-ambient thermal resistance.
Note 4. Output voltage temperature coefficient is ΔVOUT (worst case) ÷ (TJ(max) - TJ(min)) where TJ(max) is +125°C and TJ(min) is 0°C.
Note 5. VDO = VIN - VOUT when VOUT decreases to 99% of its nominal output voltage with VIN = VOUT + 1V. For output voltages below 2.25V,
dropout voltage is the input-to-output voltage differential with the minimum input voltage being 2.25V. Minimum input operating voltage
is 2.25V.
Note 6. IGND is the quiescent current. IIN = IGND + IOUT.
Note 7. Delay time is measured after VEN=VIN. CIN=COUT=10μF.
Note 8. For adjustable device and fixed device with VOUT ≥ 2.5V
Note 9. VREF ≤ VOUT ≤ (VIN - 1V), 2.25V ≤ VIN ≤ 16V, 10mA ≤ IL ≤ 1 A.

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102
TYPICAL OPERATING CHARACTERISTICS

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102
TYPICAL OPERATING CHARACTERISTICS

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

APPLICATION INFORMATION

The LM37100/1/2 is a high-performance low-dropout voltage regulator suitable for moderate to high-current
voltage regulator applications. Its 630mV dropout voltage at full load and 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 the
base-to-emitter voltage drop and collector-to-emitter saturation 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 LM37100/1/2 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. Transient 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 LM37100/1/2 requires an output capacitor to maintain stability and improve transient response. Proper
capacitor selection is important to ensure proper operation. The LM37100/1/2 output capacitor selection is
dependent upon the ESR (equivalent series resistance) of the output capacitor to maintain stability. When the
output capacitor is 10μF or greater, 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 ceramic chip
capacitors, may promote the 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 a
good transient response and the stability over the temperature range. Aluminum electrolytes can also be used,
as long as the capacitor ESR is <2Ω. The value of the output capacitor can be increased without limit. Higher
capacitance values help one to improve transient response and ripple rejection and reduce an output noise.

Input Capacitor
An input capacitor of 1μF or greater is recommended when the device is more than 4 inches away from the
bulk ac supply capacitance or when the supply is a battery. In the case of ceramic chip capacitor, 10uF
capacitance is recommended. 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 LM37101 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 is an open-collector output that pulls low
under fault conditions and may sink up to 10mA. Low output voltage signifies a number of possible problems,
including an over current fault (the device is in current limit) or low input voltage. The flag output is inoperative
during over temperature conditions. A pull-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.

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

Enable Input
The LM37101 and LM37102 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 up to the maximum supply voltage

Transient Response and 3.3V to 2.5V or 2.5V to 1.8V Conversion

The LM37100/1/2 has excellent transient response to variations 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, with typical dropout requirements of 1.2V or greater. To convert down to 2.5V or 1.8V
without operating in dropout, NPN-based regulators require an input voltage of 3.7V at the very least. The
LM37100 regulator will provide excellent performance with an input as low as 3.0V or 2.5V respectively. This
gives the PNP based regulators a distinct advantage over older, NPN based linear regulators.

Minimum Load Current

The LM37100/1/2 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 LM37102 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 Vout 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). The current consumed by feedback resisters R1 and R2 is
calculated by: Ires = Vout / (R1+ R2).

Figure 1. Adjustable Regulator with Resistors

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

Maximum Output Current Capability

The LM37100/1/2 can deliver a continuous current of 1A over the full operating junction temperature range.
However, the output current is limited by the restriction of power dissipation which differs from packages. A heat
sink may be required depending on the maximum power dissipation and maximum ambient temperature of

application. With respect to the applied package, the maximum output current of 1A may be still undeliverable
due to the restriction of the power dissipation of LM37100/1/2. Under all possible conditions, the junction
temperature must be within the range specified under operating conditions. The temperatures over the device
are given by:

TC = TA + PD X θCA / TJ = TC + PD X θJC / TJ = TA + PD X θJA

where TJ is the junction temperature, T C is the case temperature, TA is the ambient temperature, PD is the total
power dissipation of the device, θCA is the thermal resistance of case-to-ambient, θJC is the thermal resistance of
junction-to-case, and θJA is the thermal resistance of junction to ambient. The total power dissipation of the
device is given by:

PD = PIN – POUT = (VIN X IIN)–(VOUT X IOUT)

= (VIN X (IOUT+IGND)) – (VOUT X IOUT) = (VIN - VOUT) X IOUT + VIN X IGND

where IGND is the operating ground current of the device which is specified at the Electrical Characteristics. The
maximum allowable temperature rise (T Rmax) depends on the maximum ambient temperature (T Amax) of the
application, and the maximum allowable junction temperature (T Jmax):

TRmax = TJmax – TAmax

The maximum allowable value for junction-to-ambient thermal resistance, θJA, can be calculated using the
formula:

θJA = TRmax / PD = (TJmax – TAmax) / PD

LM37100/1/2 is available in SOP-8 package. The thermal resistance depends on amount of copper area or heat
sink, and on air flow. If the maximum allowable value of θJA calculated above is over 130°C/W for SOP-8
package, no heat sink is needed since the package can dissipate enough heat to satisfy these requirements. If
the value for allowable θJA falls near or below these limits, a heat sink or proper area of copper plane is required.
In summary, the absolute maximum ratings of thermal resistances are as follow:

Absolute Maximum Ratings of Thermal Resistance

Characteristic Symbol Rating Unit
Thermal Resistance Junction-To-Ambient / SOP-8 θJA-SOP-8 130 °C/W
Thermal Resistance Junction-To-Ambient / TO-252 θJA-TO-252 105 °C/W
Thermal Resistance Junction-To-Ambient / SOT-223 θJA-SOT-223 137 °C/W
2
No heat sink / No air flow / No adjacent heat source / 20 mm copper area. (TA=25°C)

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

Power Disspation(Pd) vs. Copper Area T h e r m a l Re s i s t a n c e ( Θ J A) v s . C o p p e r Ar e a

@ TJ=125℃
1.6 140

W )(
T h e rm a l R e s i s t a n c e , Θ℃J/A
Power disspation, Pd (W)

1.4
120

1.2
100

80
0.8

60
0.6

0.4 40
10 100 1000 10 100 1000
Copper Area (mm2) 2
C o p p e r Ar e a ( m)m

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1A Low-Voltage Low-Dropout Regulator LM37100/1/37102

REVISION NOTICE

The description in this data sheet can be revised without any notice to describe its electrical characteristics
properly.

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