
LD1085
SERIES
3A LOW DROP FIXED AND ADJUSTABLE
POSITIVE VOLTAGE REGULATORS
May 2000
BLOCKDIAGRAM
D
2
PAK
■ TYPICALDROPOUT VOLTAGE1.3V AT3A
■ THREETERMINALADJUSTABLEOR FIXED
OUTPUTVOLATGE1.8V,2.5V,2.85V,3.3V,
3.6V,5V,8V, 9V, 12V
■ GUARANTEEDOUTPUTCURRENTUP TO
3A
■ OUTPUTTOLERANCE±1% AT 25
o
C AND
±2% IN FULLTEMPERATURERANGE
■
INTERNALPOWERAND THERMALLIMIT
■ WIDEOPERATINGTEMPERATURERANGE
-40
o
C TO 125oC
■
PACKAGEAVAILABLE:TO-220D2PAK
■ PINOUTCOMPATIBILITYWITHSTANDARD
ADJUSTABLEVOLTAGEREGULATORS
DESCRIPTION
The LD1085 is a LOW DROP Voltage Regulator
able to provide up to 3A of Output Current.
Dropout is guaranteed at a maximum of 1.5V at
the maximum output current, decreasing at
lower loads. The LD1085 is pin compatible with
older 3-terminal adjustable regulators, but has
better performances in term of drop and output
tolerance. A 2.85V output version is suitable for
SCSI-2 active termination. Unlike PNP
regulators, where a part of the output current is
wasted as quiescent current, the LD1085
quiescent current flow into the load, so increase
efficency. Only a 10µF minimum capacitor is
need for stability. The device is supplied in
TO-220, D
2
PAK and D2PAK/A packages. On
chip trimming allows the regulator to reach a
very tight output voltage tolerance, within±1%
at 25
o
C.
TO-220
D
2
PAK/A
1/15

ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
V
IN
DC InputVoltage 30 V
I
OUT
OutputCurrent Internally Limited mA
P
tot
PowerDissipation Internally Limited mW
T
stg
Storage TemperatureRange -50 to 150
o
C
T
op
OperatingJunction Temperature Range -40 to 125
o
C
Absolute Maximum Ratings are those value beyond which damage to the device may occur. Functional operation under these condition is
not implied. Over the above suggested Max Power Dissipation a ShortCircuit could definetively damage the device.
THERMALDATA
Symbol Parameter TO-220 D2PAK Unit
R
thj-cas e
R
thj-amb
Thermal Resistance Junction-case
Thermal Resistance Junction-ambient
3
50
3
62.5
o
C/W
o
C/W
APPLICATION CIRCUIT FOR FIXED AND ADJUSTABLE VERSION
CONNECTION DIAGRAM AND ORDERING NUMBERS
(top view)
TO-220 D2PAK (**) D2PAK/A (**) Output Voltage
LD1085V18
LD1085V25
LD1085V28
LD1085V33
LD1085V36
LD1085V50
LD1085V80
LD1085V90
LD1085V120
LD1085D2T18
LD1085D2T25
LD1085D2T28
LD1085D2T33
LD1085D2T36
LD1085D2T50
LD1085D2T80
LD1085D2T90
LD1085D2T120
LD1085D2M18
LD1085D2M25
LD1085D2M28
LD1085D2M33
LD1085D2M36
LD1085D2M50
LD1085D2M80
LD1085D2M90
LD1085D2M120
1.8V
2.5V
2.85V
3.3V
3.6V
5V
8V
9V
12V
LD1085V LD1085D2T LD1085D2M 1.25 to 28V
(**)Available in Tape & Reel with the suffix ”R” for fixed version and ”-R” for adjustable version.
TO-220 D2PAK D2PAK/A
VO=
V
REF
(1 +
R
2
R
1
)
LD1085 SERIES
2/15

ELECTRICAL CHARACTERISTICS FOR LD1085#25
(refer to the test circuits,
T
j
= -40 to 125oC, VIN= 5.5 V, CIN=CO=10µF unless otherwisespecified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC 2.475 2.5 2.525 V
V
O
OutputVoltage(Note 1) IO= 0 to3 A Vin=4.1to 30 V 2.45 2.5 2.55 V
∆
V
O
LineRegulation Vin=4.1to 18 V IO= 0 mA Tj=25oC0.25mV
∆
V
O
LineRegulation Vin=4.1to 18 V IO=0mA 0.4 5 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC210mV
∆
V
O
LoadRegulation IO= 0 to3 A 4 20 mV
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent Vin≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
in
=7.5±3V
60 72 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
ELECTRICAL CHARACTERISTICS FOR LD1086#18
(refer to the test circuits,
T
j
= -40 to 125oC, VIN= 4.8 V, CIN=CO=10µF unless otherwisespecified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC 1.782 1.8 1.818 V
V
O
OutputVoltage(Note 1) IO= 0 to3 A VIN=3.4to 30 V 1.764 1.8 1.836 V
∆
V
O
LineRegulation VIN=3.4 to18V IO= 0 mA Tj=25oC0.24mV
∆
V
O
LineRegulation VIN=3.4 to18V IO=0mA 0.4 4 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC210mV
∆
V
O
LoadRegulation IO= 0 to3 A 4 20 mV
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent VIN≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
IN
=5.3±1V
60 75 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
LD1085 SERIES
3/15

ELECTRICAL CHARACTERISTICS FOR LD1085#285
(referto the testcircuits,
T
j
= -40 to 125oC, VIN= 5.85 V, CIN=CO=10µF unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC 2.821 2.85 2. 879 V
V
O
OutputVoltage(Note 1) IO= 0 to3 A VIN=4.5to 30 V 2.793 2.85 2.907 V
∆
V
O
LineRegulation VIN=4.5to 18 V IO= 0 mA Tj=25oC0.26mV
∆
V
O
LineRegulation VIN=4.5to 18 V IO=0mA 0.5 6 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC315mV
∆
V
O
LoadRegulation IO= 0 to3 A 7 20 mV
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent VIN≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
IN
=7.85±3V
60 72 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
ELECTRICAL CHARACTERISTICS FOR LD1085#33
(refer to the test circuits,
T
j
= -40 to 125oC, VIN= 6.3 V, CIN=CO=10µF unless otherwisespecified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC 3.267 3.3 3.333 V
V
O
OutputVoltage(Note 1) IO= 0 to3 A VIN=4.9to 30 V 3.234 3.3 3.366 V
∆
V
O
LineRegulation VIN=4.9to 18 V IO= 0 mA Tj=25oC0.56mV
∆
V
O
LineRegulation VIN=4.9to 18 V IO=0mA 1 6 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC315mV
∆
V
O
LoadRegulation IO= 0 to3 A 7 20 mV
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent VIN≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
IN
=8.3±3V
60 72 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
LD1085 SERIES
4/15

ELECTRICAL CHARACTERISTICS FOR LD1085#36
(refer to the test circuits,
T
j
= -40 to 125oC, VIN= 5.85 V, CIN=CO=10µF unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC 3.564 3.6 3.636 V
V
O
OutputVoltage(Note 1) IO= 0 to3 A VIN=5.2to 30 V 3.528 3.6 3.672 V
∆
V
O
LineRegulation VIN=5.2to 18 V IO= 0 mA Tj=25oC0.510mV
∆
V
O
LineRegulation VIN=5.2to 18 V IO= 0 mA 1 10 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC315mV
∆
V
O
LoadRegulation IO= 0 to3 A 7 20 mV
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent VIN≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
IN
=8.6±3V
60 72 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
ELECTRICAL CHARACTERISTICS FOR LD1085#50
(refer to the test circuits,
T
j
= -40 to 125oC, VIN= 8 V, CIN=CO=10µF unless otherwisespecified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
O
OutputVoltage IO= 0 mA Tj=25oC4.9555.05V
V
O
OutputVoltage(Note 1) IO= 0 to3 A VIN=6.6to 30 V 4.9 5 5.1 V
∆
V
O
LineRegulation VIN=6.6to 20 V IO= 0 mA Tj=25oC0.510mV
∆
V
O
LineRegulation VIN=6.6to 20 V IO= 0 mA 1 10 mV
∆
V
O
LoadRegulation IO= 0 to3 A Tj=25oC520mV
∆
V
O
LoadRegulation IO= 0 to3A 10 35 m V
V
d
Dropout Voltage IO=3A 1.3 1.5 V
I
d
QuiescentCurrent VIN≤ 30 V 5 10 mA
I
SC
ShortCircuitCurrent VIN-VO=5V
V
IN-VO
=25V
3.2
0.2
4.5
0.5
A
Thermal Regulation T
a
=25oC 30ms Pulse 0.008 0.04 %/W
SVR Supply VoltageRejection I
O
= 3 A f= 120 Hz CO=25µF
V
IN
=10±3V
60 72 dB
eN OutputNoise Voltage B = 10Hzto 10KHz T
a
=25oC 0.003 %
S Temperature Stability 0.5 %
S Long Term Stability 1000 hrs T
a
= 125oC0.5%
Note1: See short-circuit curve for available output current at fixed dropout.
LD1085 SERIES
5/15