This is information on a product in full production.
November 201 3 DocID8223 Rev 10 1/17
LD1085C
3 A low-drop, adjustable positive voltage regulator
Datasheet
-
production data
Features
•Typical dropout 1.3 V (at 3 A)
•3-terminal adjustable output voltage
•Guaranteed output current up to 3 A
•Output tolerance ± 2% at 25 °C and ± 3% in full
temperature range
•Internal power and thermal limit
•Wide operating temperature range -40 °C to
125 °C
•Package available: DPAK
•Pinout compatibility with standard adjustable
VREG
Description
The LD1085C is a low-drop voltage regulator,
providing up to 3 A of output current.The dropout
is guaranteed to be as low as 1.5 V at the
maximum current and it decreases at lower loads.
The LD1085C is pin-to-pin compatible with the old
3-terminal adjustable regulators, but it has better
performances in terms of drop and output
tolerance.
Unlike PNP regulators, where a part of the output
current is wasted as quiescent current, the
LD1085C quiescent current flows into the load, so
to increase the efficiency. A minimum capacitor of
10 µF is needed for stability.
The device is supplied in DPAK. The on-chip
trimming allows the regulator to reach a very tight
output voltage tolerance, within ± 2% at 25 °C.
DPAK
Table 1. Device summary
Order code Package
LD1085CDT-R DPAK (tape and reel)
www.st.com
Contents LD1085C
2/17 DocID8223 Rev 1 0
Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Schematic application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Typical applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8 Packaging mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
DocID8223 Rev 10 3/17
LD1085C Diagram
17
1 Diagram
Figure 1. Schematic diag ram
Pin configuration LD1085C
4/17 DocID8223 Rev 1 0
2 Pin configuration
Figure 2. Pin connections (top view)
DocID8223 Rev 10 5/17
LD1085C Maximum ratings
17
3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 2. Absolute maximum ratings
Symbol Parameter Value Unit
V
I
DC input voltage 30 V
I
O
Output current Internally limited
P
D
Power dissipation Internally limited
T
STG
Storage temperature range -55 to +150 °C
T
OP
Operating junction temperature range -40 to +125 °C
Table 3. Thermal data
Symbol Parameter DPAK Unit
R
thJC
Thermal resistan ce junction-c ase 3 °C/W
R
thJA
Thermal resistance junction-ambient 62.5 °C/W
Schematic ap plica tion LD1085C
6/17 DocID8223 Rev 1 0
4 Schematic application
Figure 3. Application circuit
V
O
V
REF
1R
2
R
1
-------+
⋅=
DocID8223 Rev 10 7/17
LD1085C Electri cal chara ct er ist ics
17
5 Electrical characteristics
V
I
= 4.25 V, C
I
= C
O
=10 µF, T
A
= -40 to 125 °C, unless otherwise specified
. Table 4. LD1085CDT electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
V
Ref
Reference voltage
(1)
I
O
= 10 mA T
J
= 25 °C 1.225 1.25 1.275 V
I
O
= 10 mA to 3 A, V
I
= 2.85 to 30 V
(1)
1.213 1.25 1.288 V
ΔV
O
Line regulation I
O
= 10 mA, V
I
= 2.85 to 16.5 V,
T
J
= 25 °C 0.015 0.2 %
I
O
= 10 mA, V
I
= 2.85 to 16.5 V 0.035 0.2 %
ΔV
O
Load regulation I
O
= 10 mA to 5 A, T
J
= 25 °C 0.1 0.3 %
I
O
= 0 to 5 A 0.2 0.4 %
V
d
Dropout voltage I
O
= 5 A 1.3 1 .5 V
I
O(min)
Minimum load current V
I
= 30 V 3 10 mA
I
sc
Short-circuit current V
I
- V
O
= 5 V 3.2 4.5 A
V
I
- V
O
= 25 V 0.2 0.5 A
Thermal regulation T
A
= 25 °C, 30 ms pulse 0.003 0.015 %/W
SVR Supply voltage rejection f = 120 Hz, C
O
= 25 µF, C
ADJ
= 25 µF,
I
O
= 3 A, V
I
= 6.25 ± 3 V 60 75 dB
I
ADJ
Adjust pin cur ren t V
I
= 4.25 V, I
O
= 10 mA 55 120 µA
ΔI
ADJ
Adjust pin current change I
O
= 10 mA to 3 A, V
I
= 2.75 to 16.5 V
(1)
0.2 5 µA
eN RMS output noise voltage
(% of V
O
)T
A
= 25 °C, f =10 Hz to 10 kHz 0.003 %
S Temperature stability 0.5 %
S Long term stability T
A
= 125 °C, 1000 hrs 0.5 %
1. See short-circuit current curve for available output current at fixed dropout.
Typical applications LD1085C
8/17 DocID8223 Rev 1 0
6 Typical applications
Unless otherwise specified T
J
= 25 °C, C
I
= C
O
= 10 µF.
Figure 4. Output voltage vs temperature Figure 5. Short-circuit current vs dropout
voltage
Figure 6. Line regulation vs temperature Figure 7. Load regulation vs temperature
DocID8223 Rev 10 9/17
LD1085C Ty pical applications
17
Figure 8. Dropout voltage vs temperature Figure 9. Dropout voltage vs output current
Figure 10. Adjust pin current vs temperature Figure 11. Quiescent current vs temperature
Figure 12. Supply voltage rejection vs output
current Figure 13. Supply voltage rejection vs
frequency
Typical applications LD1085C
10/17 DocID8223 Rev 10
Figure 14. Supply volt age rejection vs
temperature Figure 15. Minimum load current vs
temperature
Figure 16. Stability Figure 17. Line transient
V
I
=12 to 13 V, I
O
=200 mA, C
I
= 1 µF (tant), C
O
=10 µF (tant),
C
ADJ
=1 µF
Figure 18. Load transient Figure 19. Load transient, no Cadj
V
I
=12 V, I
O
=0.12 to 3 A, C
I
= 1 µF (tant), C
O
=10 µF (tant),
C
ADJ
=1 µF
V
I
=12 V, I
O
=0.12 to 3 A, C
I
= 1 µF (tant), C
O
=10 µF (tant), no
C
ADJ
DocID8223 Rev 10 11/17
LD1085C Package mechanical data
17
7 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK
®
packages, depending on their level of environmental compliance. ECOPACK
®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK
®
is an ST trademark.
Table 5. DPAK mechanical data
Dim. mm
Min. Typ. Max.
A2.20 2.40
A1 0.90 1.10
A2 0.03 0.23
b0.64 0.90
b4 5.20 5.40
c0.45 0.60
c2 0.48 0.60
D6.00 6.20
D1 5.10
E6.40 6.60
E1 4.70
e2.28
e1 4.40 4.60
H 9.35 10.10
L1.00 1.50
(L1) 2.80
L2 0.80
L4 0.60 1.00
R0.20
V2 0° 8°
Package mechanical data LD1085C
12/17 DocID8223 Rev 10
Figure 20. DPAK draw ing
0068772_K
DocID8223 Rev 10 13/17
LD1085C Package mechanical data
17
Figure 21. DPAK footprint
(a)
a. All dimensions are in millimeters
Footprint_REV_K
Packagi ng mechan ic al data LD1085C
14/17 DocID8223 Rev 10
8 Packaging mechanical data
Table 6. DPAK tape and reel mechanical data
Tape Reel
Dim. mm Dim. mm
Min. Max. Min. Max.
A0 6.8 7 A 330
B0 10.4 10.6 B 1.5
B1 12.1 C 12.8 13.2
D 1.5 1.6 D 20.2
D1 1.5 G 16.4 18.4
E 1.65 1.85 N 50
F 7.4 7.6 T 22.4
K0 2.55 2.75
P0 3.9 4.1 Base qty. 2500
P1 7.9 8.1 Bulk qty. 2500
P2 1.9 2.1
R40
T 0.25 0.35
W 15.7 16.3
DocID8223 Rev 10 15/17
LD1085C Packaging mechanical data
17
Figure 22. Tape for DPAK
Figure 23. Reel for DPAK
P1
A0 D1
P0
F
W
E
D
B0
K0
T
User direction of feed
P2
10 pitches cumulative
tolerance on tape +/- 0.2 mm
User direction of feed
R
Bending radius
B1
For machine ref. only
including draft and
radii concentric around B0
AM08852v1
Top cover
tape
A
D
B
Full radius G measured at hub
C
N
REEL DIMENSIONS
40mm min.
Access hole
At sl ot location
T
Tape slot
in core for
tape start 25 mm min.
width
AM08851v2
Revision history LD1085C
16/17 DocID8223 Rev 10
9 Revision history
Table 7. Document revision history
Date Revision Changes
07-Oct-2004 6 Mistake in Table 1.
03-Jul-2007 7 Order codes updated.
09-Apr-2008 8 Modified: Table 1 on page 1.
11-Jul-2013 9
Updated Description in cover page, Figure 2, Figure 3 and Table 4.
Modified Section 6: Typical applications and Se cti on 7: Packag e
mechanical data.
Added Section 8: Packaging mechanical data.
Minor text chan ges .
04-Nov-2013 10 RPN LD1085CXX cha ng ed to LD1 085 C.
Updated the Description in cover page.
Minor text chan ges .
DocID8223 Rev 10 17/17
LD1085C
17
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