LM1085-XXXJ3

CYStech Electronics Corp.
3A Low Dropout Positive Voltage Regulator
TO-252AB
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 1/9
TO-252AA
LM1085-XXXJ3
Features
Dropout Voltage 1.4V at 3A Output Current.
Fast Transient Response.
Extremely Tight Line and Load Regulation.
Built-in Thermal Shutdown Protection.
Adjustable Output Voltage or Fixed 1.5V, 1.8V, 2.5V, 3.3V, 5.0V.
Output Current Limiting.
Adj/G
O I
Adj/G
O I
Description
The LM1085-XXXJ3 is a low dropout three terminal regulator with 3A output current capability. The output voltage is
adjustable with the use of a resistor divider or fixed 1.5V, 1.8V, 2.5V, 3.3V and 5.0V. Dropout voltage is guaranteed to be at
maximum of 1.4V with the maximum output current. Its low dropout voltage and fast transient response make it ideal for
low voltage microprocessor applications. Current limit and thermal protection provide protection against any overload
condition that would create excessive junction temperatures.
Applications
Mother Board I/O Power Supplies.
Microprocessor Power Supplies.
High Current Regulator.
Post Regulator for Switching Supply.
Ordering Information
Device
LM1085-XXXJ3-0-T3-G
Package
TO-252
(Pb-free lead plating and halogen-free package)
Shipping
2500 pcs / tape & reel
Environment friendly grade : S for RoHS compliant products, G for RoHS compliant and
green compound products
Packing spec, T3 : 2500 pcs / tape & reel, 13” reel
Product rank, zero for no rank products
Product name
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 2/9
Typical Application Circuit
Vin=5V
Vout=3.3V
LM1085
ADJ
VREF
C1
10μF
10μF
R1
125Ω
1%
C2
22μF
R2
205Ω
1%
VREF=VOUT-VADJ=1.25V(typ)
VOUT=VREF(1+R1/R2)+IADJ ×R2
IADJ=55μA(typ.)
(1)C1 needed if device is far
away from filter capacitors.
(2)C2 minimum value required
for stability.
Adjustable Voltage Regulator
Vout=3.3V
Vin=5V
LM1085-3.3
C2
22μF
C1
10μF
GND
Fixed Voltage Regulator
Absolute Maximum Ratings
Symbol
Vin
PD
TSTG
TOPR
TLEAD
LM1085-XXXJ3
Parameter
DC supply voltage
Power Dissipation
Storage Temperature Range
Operation Junction Temperature Range
Lead Temperature(Soldering 10 seconds)
Ratings
15
Internally Limited
-65 ~ +150
-40 ~ +125
300
Unit
V
W
℃
℃
℃
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 3/9
Electrical Characteristics (IO=10mA,Tj=25℃,unless otherwise noted)
Symbol
VREF
Parameter
Reference Voltage
Vo
Output Voltage
(fixed versions)
ΔVo
Line Regulation
ΔVo
Is
IAdj
IQ
Ts
IL
RR
VD
Rth, j-a
Rth, j-c
Load Regulation
Conditions
LM1085-Adj, Vin =5V
LM1085-1.5, 3.0V≤Vin≤12V
LM1085-1.8, 3.3V≤Vin≤12V
LM1085-2.5, 4.0V≤Vin≤12V
LM1085-3.3, 4.8V≤Vin≤12V
LM1085-5.0, 6.5V≤Vin≤12V
Adj : 2.75V≤Vin≤12V
Fixed : 1.5+Vout≤Vin≤12V
LM1085-Adj,Vin=3.3V, 10mA≤Io≤3A (Note 1, 2)
LM1085-1.5, Vin=3.0V, 10mA≤IO≤3A(Note 1, 2)
LM1085-1.8, Vin=3.3V, 10mA≤IO≤3A(Note 1, 2)
LM1085-2.5, Vin=4.0V, 10mA≤IO≤3A(Note 1, 2)
LM1085-3.3, Vin=5.0V, 10mA≤IO≤3A(Note 1, 2)
LM1085-5.0, Vin=8.0V, 10mA≤IO≤3A(Note 1, 2)
Vin-Vout=5V
Adjustable model, Vin=12V, Iout=10mA
Fixed model, Vin=12V, IO=10mA
Current Limit
Adjust Pin Current
Quiescent Current
Temperature Stability
IO=10mA, 0°C≤Tj≤125°C
Minimum Load Current Adjustable model, Vin=5V
VIN-VOUT=3V, IO=3A, f=120Hz,
Ripple Rejection Ratio
COUT=25μF, tantalum
Dropout Voltage
IO=3A(ΔVOUT=1%VOUT)
Thermal Resistance,
No heat sink, no air flow
Junction to Ambient
Thermal Resistance,
Control Circuitry/Power Transistor
Junction to Case
Min
Typ
Max Units
1.225
1.470
1.764
2.450
3.235
4.900
1.250
1.500
1.800
2.500
3.300
5.000
1.275
1.530
1.836
2.550
3.365
5.100
-
-
0.2
%
3
-
12
15
20
26
40
4.5
40
7
0.5
3
1
15
18
25
33
50
100
12
10
%
mV
mV
mV
mV
mV
A
μA
60
65
-
dB
-
1.3
1.4
V
-
98
-
℃/W
-
15
-
℃/W
V
V
mA
%
mA
Note : 1.See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured at
a constant junction temperature by low duty cycle pulse testing. Load regulation is measured at the output lead 1/18” from the
package.
2. Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by the
difference in input and output and the output current. Guaranteed maximum power dissipation will not be available over the full
input/output range.
Recommended soldering footprint
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 4/9
Block Diagram
Functional Description
Introduction
The LM1085 adjustable or fixed-mode Low Dropout(LDO) regulator is a 3 terminal device which can easily be
programmed by internal mask change to any voltage within the range of 1.25V to Vin-1.4V. The LM1085 only needs
1.4V differential between Vin and Vout to maintain output regulation. In addition, the output voltage tolerances are
also extremely tight and they include the transient response as part of the specification. For example, Intel VRE
specification calls for a total of ±100mV including initial tolerance, load regulation and 0 to 3A load step. The
LM1085 is specifically designed to meet the fast current transient needs as well as providing an accurate initial
voltage, reducing the overall system cost with the need for fewer output capacitors.
The LM1085 series of adjustable and fixed regulators are easy to use and have all the protection features expected
in high performance voltage regulators : short circuit protection and thermal shutdown.
Load Regulation
Since the LM1085 is only a 3 terminal device, it is not possible to provide true remote sensing of output voltage at the
load. The resistance of the wire connecting the regulator to the load will limit the load regulation.
The data sheet specification for load regulation is measured at the bottom of the package. Negative side sensing is a
true Kelvin connection, with the bottom of the output divider returned to the negative side of the load.
The best load regulation is obtained when the top of the resistor divider R1 is connected directly to the case, not to the
load. If R1 is connected to the load, the effective resistance between the regulator and the load would be :
RP×(R1+R2)
R1
, RP=Parasitic Line Resistance
Using 16-gauge wire, the parasitic line resistance is about
0.004Ωper feet, translating to 4mV/ft at 1A load current.
It is important to keep the positive lead between regulator
and load as short as possible and use large wire or PC
board traces.
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 5/9
Stability
The LM1085 requires the use of an output capacitor as part of the frequency compensation in order to make the
regulator stable. For most applications, the addition of 150μF aluminum electrolytic capacitor or a 22μF solid
tantalum on the output will ensure stability for all operating conditions.
When the adjustment terminal is bypassed with a capacitor to improve the ripple rejection, the requirement for an
output capacitor increases. The value of 22μF tantalum or 150μF aluminum covers all cases of bypassing the
adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good
results. To ensure good transient response with heavy load current changes capacitor values on the order of 100μF
are used in the output of many regulators. To further improve stability and transient response of these devices larger
values of output capacitor can be used.
Protection Diodes
Unlike older regulators, the LM1085 family does not need any protection diodes between the adjustment pin and the
output and from the output to the input to prevent over-stressing the die.
Internal resistors are limiting the internal current paths on the adjustment pin, therefore even with capacitors on the
adjustment pin, no protection diode is needed to ensure device safety under short-circuit conditions.
If high value output capacitors are used, such as 1000μF to 5000μF, and the input pin is instantaneously shorted to
ground, damage can occur. A diode from output to input is recommended, when a crowbar circuit at the input of the
LM1085 is used. Normal power supply cycling or even plugging and unplugging in the system will not generate
current large enough to do any damage.
Thermal Design
The LM1085 incorporates an internal power and thermal limiting circuitry designed to protect the device under
overload conditions. However maximum junction temperature ratings should not be exceeded under continuous
normal load conditions.
Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junctionto-case, case to heat sink interface and heat sink resistance itself. To ensure safe operating temperatures and reflect
more accurately the device temperature, new thermal resistance specifications have been developed.
Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die.
This is the lowest resistance path for the heat flow. In order to ensure the best possible thermal flow from this area
of the package to the heat sink, proper mounting is required. Thermal compound at the case-to-heat sink interface is
recommended. A thermally conductive spacer can be used, if the case of the device must be electrically isolated, but
its added contribution to thermal resistance has to be considered.
Layout Consideration
The output capacitors must be located as close to the Vout terminal of the device as possible. It is recommended to
use a section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any high
frequency oscillation that may result due to excess trace inductance.
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 6/9
Reel Dimension
Carrier Tape Dimension
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 7/9
Recommended wave soldering condition
Product
Pb-free devices
Peak Temperature
260 +0/-5 °C
Soldering Time
5 +1/-1 seconds
Recommended temperature profile for IR reflow
Profile feature
Average ramp-up rate
(Tsmax to Tp)
Preheat
−Temperature Min(TS min)
−Temperature Max(TS max)
−Time(ts min to ts max)
Time maintained above:
−Temperature (TL)
− Time (tL)
Peak Temperature(TP)
Time within 5°C of actual peak
temperature(tp)
Ramp down rate
Time 25 °C to peak temperature
Sn-Pb eutectic Assembly
Pb-free Assembly
3°C/second max.
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
183°C
60-150 seconds
240 +0/-5 °C
217°C
60-150 seconds
260 +0/-5 °C
10-30 seconds
20-40 seconds
6°C/second max.
6 minutes max.
6°C/second max.
8 minutes max.
Note : All temperatures refer to topside of the package, measured on the package body surface.
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 8/9
TO-252AB Dimension
Marking:
4
Device
Name
Date
Code
3-Lead TO-252AB Plastic Surface Mount Package
CYStek Package Code: J3
1085□□□
□□□□
1.5V→-15
1.8V→-18
2.5V→-25
3.3V→-33
5.0V→-50
ADJ→blank
Style: Pin 1.ADJ/GND 2.Vout 3.Vin
4.Vout
*: Typical
Inches
Min.
Max.
0.087
0.094
0.000
0.005
0.053
0.065
0.020
0.028
0.028
0.035
0.017
0.023
0.017
0.023
0.250
0.262
0.205
0.213
0.213
0.224
DIM
A
A1
B
b
b1
C
C1
D
D1
E
Millimeters
Min.
Max.
2.200
2.400
0.000
0.127
1.350
1.650
0.500
0.700
0.700
0.900
0.430
0.580
0.430
0.580
6.350
6.650
5.200
5.400
5.400
5.700
DIM
e
e1
H
K
L
L1
L2
L3
P
V
Inches
Min.
Max.
*0.091
0.177
0.185
0.118 REF
0.197 REF
0.374
0.390
0.100
0.114
0.055
0.070
0.024
0.035
0.028 REF
0.209 REF
Millimeters
Min.
Max.
*2.300
4.500
4.700
3.000 REF
5.000 REF
9.500
9.900
2.550
2.900
1.400
1.780
0.600
0.900
0.700 REF
5.300 REF
Notes: 1.Controlling dimension: millimeters.
2.Maximum lead thickness includes lead finish thickness, and minimum lead thickness is the minimum thickness of base material.
3.If there is any question with packing specification or packing method, please contact your local CYStek sales office.
Material:
• Lead : Pure tin plated
• Mold Compound: Epoxy resin family, flammability solid burning class: UL94V-0
LM1085-XXXJ3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C540J3
Issued Date : 2003.06.25
Revised Date :2013.09.11
Page No. : 9/9
TO-252AA Dimension
Marking:
4
Device
Name
Date
Code
1085□□□
□□□□
1
3-Lead TO-252AA Plastic Surface Mount Package
CYStek Package Code: J3
Inches
Min.
Max.
0.087
0.094
0.000
0.005
0.039
0.048
0.026
0.034
0.026
0.034
0.018
0.023
0.018
0.023
0.256
0.264
0.201
0.215
0.236
0.244
DIM
A
A1
B
b
b1
C
C1
D
D1
E
Millimeters
Min.
Max.
2.200
2.400
0.000
0.127
0.990
1.210
0.660
0.860
0.660
0.860
0.460
0.580
0.460
0.580
6.500
6.700
5.100
5.460
6.000
6.200
1.5V→-15
1.8V→-18
2.5V→-25
3.3V→-33
5.0V→-50
ADJ→
blank
2
3
Style: Pin 1.ADJ/GND 2.Vout 3.Vin
4.Vout
DIM
e
e1
H
K
L
L1
L2
L3
P
V
Inches
Min.
Max.
0.086
0.094
0.172
0.188
0.163 REF
0.190 REF
0.386
0.409
0.114 REF
0.055
0.067
0.024
0.039
0.026 REF
0.211 REF
Millimeters
Min.
Max.
2.186
2.386
4.372
4.772
4.140 REF
4.830 REF
9.800
10.400
2.900 REF
1.400
1.700
0.600
1.000
0.650 REF
5.350 REF
Notes: 1.Controlling dimension: millimeters.
2.Maximum lead thickness includes lead finish thickness, and minimum lead thickness is the minimum thickness of base material.
3.If there is any question with packing specification or packing method, please contact your local CYStek sales office.
Material:
• Lead : Pure tin plated.
• Mold Compound: Epoxy resin family, flammability solid burning class: UL94V-0.
Important Notice:
• All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of CYStek.
• CYStek reserves the right to make changes to its products without notice.
• CYStek semiconductor products are not warranted to be suitable for use in Life-Support Applications, or systems.
• CYStek assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.
LM1085-XXXJ3
CYStek Product Specification