5 A low drop positive voltage regulator adjustable
Features
■ Typical dropout 1.3 V (at 5 A)
■ Three terminal adjustable output voltage
■ Guaranteed output current up to 5 A
■ Output tolerance ± 1 % at 25 °C and ± 2 % in
full temperature range
■ Internal power and thermal limit
■ Wide operating temperature range -40 °C to
125 °C
■ Package available: TO-220
■ Pinout compatibility with standard adjustable
VREG
Description
The LD1084XX is a low drop voltage regulator
able to provide up to 5 A of output current.
Dropout is guaranteed at a maximum of 1.5 V at
the maximum output current, decreasing at lower
loads. The LD1084XX is pin to pin compatible
with the older 3-terminal adjustable regulators, but
has better performances in term of drop and
output tolerance.
LD1084XX
TO-220
The device is supplied in TO-220. On chip
trimming allows the regulator to reach a very tight
output voltage tolerance, within ± 1 % at 25 °C.
A 2.85 V 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 LD1084XX quiescent current flows
into the load, so increase efficiency. Only a 10 µF
minimum capacitor is need for stability.
Table 1. Device summary
Order code Output voltage
LD1084V Adjustable
July 2009 Doc ID 9035 Rev 9 1/16
www.st.com
16
Contents LD1084XX
Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Schematic application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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LD1084XX Diagram
1 Diagram
Figure 1. Schematic diagram
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Pin configuration LD1084XX
2 Pin configuration
Figure 2. Pin connections (top view)
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LD1084XX Maximum ratings
3 Maximum ratings
Table 2. Absolute maximum ratings
Symbol Parameter Value Unit
T
P
T
V
I
I
O
D
STG
OP
DC input voltage 30 V
Output current Internally limited mA
Power dissipation Internally limited mW
Storage temperature range -55 to +150 °C
Operating junction temperature range -40 to +125 °C
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
Table 3. Thermal data
Symbol Parameter TO-220 Unit
R
R
thJC
thJA
Thermal resistance junction-case 3 °C/W
Thermal resistance junction-ambient 50 °C/W
Doc ID 9035 Rev 9 5/16
Schematic application LD1084XX
4 Schematic application
Figure 3. Application circuit
R
2
VOV
⎛⎞
1
⋅=
REF
⎝⎠
------ -+
R
1
6/16 Doc ID 9035 Rev 9
LD1084XX Electrical characteristics
5 Electrical characteristics
VI = 4.25 V, CI = CO =10 µF, TA = -40 to 125 °C, unless otherwise specified.
Table 4. Electrical characteristics of LD1084XX
Symbol Parameter Test condition Min. Typ. Max. Unit
V
ΔV
ΔV
V
I
O(min)
Output voltage
O
Line regulation
O
Load regulation
O
Dropout voltage IO = 5A 1.3 1.5 V
d
(1)
Minimum load current VI = 30V 3 10 mA
IO = 10mA TJ = 25°C 1.237 1.25 1.263 V
= 10mA to 3A, VI = 2.85 to 30V 1.225 1.25 1.275 V
I
O
= 10mA, VI = 2.85 to 16.5V,
I
O
= 25°C
T
J
= 10mA, VI = 2.85 to 16.5V 0.035 0.2 %
I
O
I
= 10mA to 5A, TJ = 25°C 0.1 0.3 %
O
I
= 0 to 5A 0.2 0.4 %
O
0.015 0.2 %
VI - VO = 5V 5.5 6.5 A
I
Short circuit current
sc
Thermal regulation T
SVR Supply voltage rejection
I
ΔI
eN
Adjust pin current VI = 4.25V, IO = 10 mA 55 120 μA
ADJ
Adjust pin current change
ADJ
RMS output noise voltage
(% of V
)
O
(1)
- VO = 25V 0.5 0.7 A
V
I
= 25°C, 30ms pulse 0.003 0.015 %/W
A
f = 120 Hz, C
IO = 5A, VI = 6.25 ± 3V
= 25µF,C
O
= 25 µF,
ADJ
60 72 dB
IO = 10mA to 5A, VI = 2.85 to 16.5V 0.2 5 μA
T
= 25°C, f =10Hz to 10kHz 0.003 %
A
S Temperature stability 0.5 %
S Long term stability T
1. See short-circuit current curve for available output current at fixed dropout.
= 125°C, 1000Hrs 0.5 %
A
Doc ID 9035 Rev 9 7/16
Typical application LD1084XX
6 Typical application
Unless otherwise specified TJ = 25 °C, CI = 10 µF (tant.), CO = 22 µF (tant.)
Figure 4. Short circuit current vs. dropout
Figure 6. Quiescent current vs. temperature Figure 7. Output voltage vs. temperature
voltage
Figure 5. Line regulation vs. temperature
Figure 8. Load regulation vs. temperature Figure 9. Quiescent current vs. output
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voltage
LD1084XX Typical application
Figure 10. Quiescent current vs. input voltage Figure 11. Dropout voltage vs. output current
Figure 12. Supply voltage rejection vs. output
current
Figure 14. Supply voltage rejection vs.
temperature
Figure 13. Dropout voltage vs. temperature
Figure 15. Supply voltage rejection vs.
frequency
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Typical application LD1084XX
Figure 16. Adjust pin current vs. output
Figure 18. Load regulation vs. temperature Figure 19. Adjust pin current vs. temperature
current
Figure 17. Reference voltage vs. temperature
Figure 20. Line regulation vs. temperature Figure 21. Minimum load current vs.
10/16 Doc ID 9035 Rev 9
temperature
LD1084XX Typical application
Figure 22. Supply voltage rejection vs.
temperature
Figure 23. Supply voltage rejection vs.
frequency
Figure 24. Stability Figure 25. Supply voltage rejection vs. output
current
Figure 26. Stability Figure 27. Line transient
VI=14 to 15V, IO=200mA,CI = 1µF(tant), CO=10µF(tant),
t
=5ms
s=tf
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Typical application LD1084XX
Figure 28. Line transient Figure 29. Load transient
VI=12 to 13V, IO=200mA, CI = 1µF(tant), CO=10µF(tant), No
C
Figure 30. Load transient Figure 31. Line transient
ADJ ts=tf
=5µs
VI=15 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant), No
C
ADJ
Figure 32. Load transient
VI=15 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant)
VI=12 to 13V, IO=200mA, CI = 1µF(tant), CO=10µF(tant),
C
= 1µF, ts=tf=5µs
ADJ
VI=13 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant)
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LD1084XX Package mechanical data
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.
Doc ID 9035 Rev 9 13/16
Package mechanical data LD1084XX
TO-220 mechanical data
Dim.
Min. Typ. Max. Min. Typ. Max.
mm. inch.
A 4.40 4.60 0.173 0.181
C1.23 1.32 0.048 0.051
D 2.40 2.72 0.094 0.107
D1 1.27 0.050
E0.49 0.70 0.019 0.027
F 0.61 0.88 0.024 0.034
F1 1.14 1.70 0.044 0.067
F2 1.14 1.70 0.044 0.067
G4.95 5.15 0.194 0.203
G1 2.4 2.7 0.094 0.106
H2 10.0 10.40 0.393 0.409
L2 16.4 0.645
L4 13.0 14.0 0.511 0.551
L5 2.65 2.95 0.104 0.116
L6 15.25 15.75 0.600 0.620
L7 6.2 6.6 0.244 0.260
L93.5 3.93 0.137 0.154
DIA. 3.75 3.85 0.147 0.151
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P011C
LD1084XX Revision history
8 Revision history
Table 5. Document revision history
Date Revision Changes
07-Oct-2004 3 Mistake order codes - Table 1.
08-Feb-2005 4 Mistake U.M. Load Regulation - V ==> mV.
16-Jun-2005 5 Order codes updated.
04-Apr-2007 6 Order code updated.
07-Jun-2007 7 Order codes updated.
08-Apr-2008 8
29-Jul-2009 9 Modified: Table 1 on page 1.
Modified: Table 1 on page 1. Removed: packages D²PAK, D²PAK/A and
mechanical data.
Doc ID 9035 Rev 9 15/16
LD1084XX
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