July 2009 Doc ID 9035 Rev 9 1/16
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LD1084XX
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.
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.
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.
TO-220
Table 1. Device summary
Order code Output voltage
LD1084V Adjustable
www.st.com
Contents LD1084XX
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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
LD1084XX Diagram
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1 Diagram
Figure 1. Schematic diagram
Pin configuration LD1084XX
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2 Pin configuration
Figure 2. Pin connections (top view)
LD1084XX Maximum ratings
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3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
Table 2. Absolute maximum ratings
Symbol Parameter Value Unit
VIDC input voltage 30 V
IOOutput current Internally limited mA
PDPower dissipation Internally limited mW
TSTG Storage temperature range -55 to +150 °C
TOP Operating junction temperature range -40 to +125 °C
Table 3. Thermal data
Symbol Parameter TO-220 Unit
RthJC Thermal resistance junction-case 3 °C/W
RthJA Thermal resistance junction-ambient 50 °C/W
Schematic application LD1084XX
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4 Schematic application
Figure 3. Application circuit
VOVREF 1R2
R1
-------+
⎝⎠
⎛⎞
⋅=
LD1084XX Electrical characteristics
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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
VOOutput voltage (1) IO = 10mA TJ = 25°C 1.237 1.25 1.263 V
IO = 10mA to 3A, VI = 2.85 to 30V 1.225 1.25 1.275 V
ΔVOLine regulation
IO = 10mA, VI = 2.85 to 16.5V,
TJ = 25°C 0.015 0.2 %
IO = 10mA, VI = 2.85 to 16.5V 0.035 0.2 %
ΔVOLoad regulation IO = 10mA to 5A, TJ = 25°C 0.1 0.3 %
IO = 0 to 5A 0.2 0.4 %
VdDropout voltage IO = 5A 1.3 1.5 V
IO(min) Minimum load current VI = 30V 3 10 mA
Isc Short circuit current VI - VO = 5V 5.5 6.5 A
VI - VO = 25V 0.5 0.7 A
Thermal regulation TA = 25°C, 30ms pulse 0.003 0.015 %/W
SVR Supply voltage rejection f = 120 Hz, CO = 25µF,CADJ = 25 µF,
IO = 5A, VI = 6.25 ± 3V 60 72 dB
IADJ Adjust pin current VI = 4.25V, IO = 10 mA 55 120 μA
ΔIADJ Adjust pin current change (1) IO = 10mA to 5A, VI = 2.85 to 16.5V 0.2 5 μA
eN RMS output noise voltage
(% of VO)TA = 25°C, f =10Hz to 10kHz 0.003 %
S Temperature stability 0.5 %
S Long term stability TA = 125°C, 1000Hrs 0.5 %
1. See short-circuit current curve for available output current at fixed dropout.
Typical application LD1084XX
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6 Typical application
Unless otherwise specified TJ = 25 °C, CI = 10 µF (tant.), CO = 22 µF (tant.)
Figure 4. Short circuit current vs. dropout
voltage
Figure 5. Line regulation vs. temperature
Figure 6. Quiescent current vs. temperature Figure 7. Output voltage vs. temperature
Figure 8. Load regulation vs. temperature Figure 9. Quiescent current vs. output
voltage
LD1084XX Typical application
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Figure 10. Quiescent current vs. input voltage Figure 11. Dropout voltage vs. output current
Figure 12. Supply voltage rejection vs. output
current
Figure 13. Dropout voltage vs. temperature
Figure 14. Supply voltage rejection vs.
temperature
Figure 15. Supply voltage rejection vs.
frequency
Typical application LD1084XX
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Figure 16. Adjust pin current vs. output
current
Figure 17. Reference voltage vs. temperature
Figure 18. Load regulation vs. temperature Figure 19. Adjust pin current vs. temperature
Figure 20. Line regulation vs. temperature Figure 21. Minimum load current vs.
temperature
LD1084XX Typical application
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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),
ts=tf=5ms
Typical application LD1084XX
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Figure 28. Line transient Figure 29. Load transient
VI=12 to 13V, IO=200mA, CI = 1µF(tant), CO=10µF(tant), No
CADJ ts=tf=5µs
VI=15 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant)
Figure 30. Load transient Figure 31. Line transient
VI=15 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant), No
CADJ
VI=12 to 13V, IO=200mA, CI = 1µF(tant), CO=10µF(tant),
CADJ = 1µF, ts=tf=5µs
Figure 32. Load transient
VI=13 V, IO=0.1 to 5 A, CI = 1µF(tant), CO=10µF(tant)
LD1084XX Package mechanical data
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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.
Package mechanical data LD1084XX
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Dim. mm. inch.
Min. Typ. Max. Min. Typ. Max.
A 4.40 4.60 0.1730.181
C1.231.32 0.0480.051
D 2.40 2.72 0.094 0.107
D1 1.27 0.050
E0.490.70 0.0190.027
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
TO-220 mechanical data
P011C
LD1084XX Revision history
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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 Modified: Table 1 on page 1. Removed: packages D²PAK, D²PAK/A and
mechanical data.
29-Jul-2009 9 Modified: Table 1 on page 1.
LD1084XX
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