This is information on a product in full production.
April 2015 DocID2141 Rev 14 1/25
L4940
1.5 A very low drop voltage regulator IC
Datasheet
-
production data
Features
•Precise 5, 8.5, 12 V outputs
•Low dropout voltage (450 mV typ. at 1 A)
•Very low quiescent current
•Thermal shutdown
•Short-circuit protec tion
•Reverse polarity protection
Description
The L4940 series of three-terminal positive
regulators is available in TO-220 and D²PAK
packages and with several fixed output voltages,
making it useful in a wide range of industrial and
consumer applications. Thanks to their very low
input/output voltage drop, these devices are
particularly suitable for battery-powered
equipment, reducing consumption and prolonging
battery-life. Each type employs internal current
limiting, anti-saturation circuit, t hermal shutdown
and safe area protection.
TO-220
D²PAK
Table 1. Device summary
Order code Output
voltages
TO-220 D²PAK
L4940V5 L4940D2T5-TR 5 V
L4940V85 8.5 V
L4940D2 T12 -TR 12 V
www.st.com
Contents L4940
2/25 DocI D2141 Rev 14
Contents
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Test circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1 T O-220 (dual gauge) pa ckage information . . . . . . . . . . . . . . . . . . . . . . . . 16
8.2 T O-220 (dual gauge) p acking information . . . . . . . . . . . . . . . . . . . . . . . . 18
8.3 D²PAK package informati on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.4 D²PAK packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DocID2141 Rev 14 3/25
L4940 Block di agram
25
1 Block diagram
Figure 1. Block diagram
Pin configuration L4940
4/25 DocI D2141 Rev 14
2 Pin configuration
Figure 2. Pin connections (top view)
D²PAK
TO-220
DocID2141 Rev 14 5/25
L4940 Maximum ratings
25
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
Forward input voltage 30 V
V
IR
Reverse input voltage
V
O
= 5 V, R
O
= 100 Ω-15 V
V
O
= 8.5 V, R
O
= 180 Ω-15 V
V
O
= 12 V, R
O
= 240 Ω-15 V
I
O
Output current Internally limited mA
P
D
Power dissipation Internally limited mW
T
stg
Storage temperature range -40 to +150 °C
T
op
Operating junction temperature range -40 to +150 °C
Table 3. Thermal data
Symbol Parameter TO-220 D²PAK Unit
R
thJC
Thermal resistance junction-case 3 3 °C/W
R
thJA
Thermal resistance junction-ambient 50 62.5 °C/W
Test circuits L4940
6/25 DocI D2141 Rev 14
4 Test circuits
Figure 3. DC p aramet ers
Figure 4. Load regulation
Figure 5. Ripple rejection
DocID2141 Rev 14 7/25
L4940 Electri cal chara ct er ist ics
25
5 Electrical characteristics
Refer to test circuit, V
I
= 7 V, C
I
= 0.1 µF, C
O
= 22 µF, T
J
= 25 °C, unless otherwise specified.
Refer to test circuit, V
I
= 10.5 V, C
I
= 0.1 µF, C
O
= 22 µF, T
J
= 25 °C, unless otherwise
specified.
Ta bl e 4. L4940 #5 electrical char acter ist ic s
Symbol Parameter Test co ndit ions Min. Typ. Max. Unit
V
O
Output voltage I
O
= 500 mA 4.9 5 5.1 V
V
O
Output voltage I
O
= 5 mA to 1.5 A, V
I
= 6.5 to 15 V 4.8 5 5.2 V
V
I
Maximum input voltage I
O
= 5 mA 17 V
ΔV
O
Line regulation V
I
= 6 to 17 V, I
O
= 5 mA 4 10 mV
ΔV
O
Load regulation I
O
= 5 mA to 1.5 A 8 25 mV
I
O
= 0.5 A to 1 A 5 15 mV
I
q
Quiescent current I
O
= 5 mA 5 8 mA
I
O
= 1.5 A, V
I
= 6.5 V 30 50 mA
ΔI
q
Quiescent current change I
O
= 5 mA 3 mA
I
O
= 1.5 A, V
I
= 6.5 to 16 V 15 mA
ΔV
O
/ ΔT Output voltage drift 0.5 mV/°C
SVR Supply voltage rejection f = 120 Hz, I
O
= 1 A 58 68 dB
V
d
Dropout voltage I
O
= 0.5 A 200 400 mV
I
O
= 1.5 A 500 900 mV
I
sc
Short-circuit current V
I
= 14 V 2 2.7 A
V
I
= 6.5 V 2.2 2.9
Table 5. L4940#85 electrical characteristics
Symbol Parameter Test co ndit ions Min. Typ. Max. Unit
V
O
Output voltage I
O
= 500 mA 8.3 8.5 8.7 V
V
O
Output voltage I
O
= 5 mA to 1.5 A, V
I
= 10.2 to 15 V 8.15 8.5 8.85 V
V
I
Maximum input voltage I
O
= 5 mA 17 V
ΔV
O
Line regulation V
I
= 9.5 to 17 V, I
O
= 5 mA 4 9 mV
ΔV
O
Load regulation I
O
= 5 mA to 1.5 A 12 30 mV
I
O
= 0.5 A to 1 A 8 16 mV
I
q
Quiescent current I
O
= 5 mA 4 8 mA
I
O
= 1.5 A, V
I
= 10.2 V 30 50 mA
ΔI
q
Quiescent current change I
O
= 5 mA 2.5 mA
I
O
= 1.5 A, V
I
= 10.2 to 16 V 15 mA
Ele ctrical characteristics L4940
8/25 DocI D2141 Rev 14
Refer to test circuit, V
I
= 14 V, C
I
= 0.1 µF, C
O
= 22 µF, T
J
= 25 °C, unless otherwise
specified.
ΔV
O
/ ΔT Output voltage drift 0.8 mV/°C
SVR Supply voltage rejection f = 120 Hz, I
O
= 1 A 58 66 dB
V
d
Dropout voltage I
O
= 0.5 A 200 400 mV
I
O
= 1.5 A 500 900 mV
I
sc
Short-circuit current V
I
= 14 V 2 2.7 A
V
I
= 10.2 V 2.2 2.9
Table 5. L4940#85 electrical characteristics (continued)
Symbol Parameter Test co ndit ions Min. Typ. Max. Unit
Table 6. L4940#12 electrical characteristics
Symbol Parameter Test co ndit ions Min. Typ. Max. Unit
V
O
Output voltage I
O
= 500 mA 11.75 12 12.25 V
V
O
Output voltage I
O
= 5 mA to 1.5 A, V
I
= 13.8 to 15 V 11.5 12 12.5 V
V
I
Maximum input voltage I
O
= 5 mA 17 V
ΔV
O
Line regulation V
I
= 13 to 17 V, I
O
= 5 mA 3 7 mV
ΔV
O
Load regulation I
O
= 5 mA to 1.5 A 15 35 mV
I
O
= 0.5 A to 1 A 10 25 mV
I
q
Quiescent current I
O
= 5 mA 4 8 mA
I
O
= 1.5 A, V
I
= 13.8 V 30 50 mA
ΔI
q
Quiescent current change I
O
= 5 mA 1.5 mA
I
O
= 1.5 A, V
I
= 13.8 to 16 V 10 mA
ΔV
O
/ΔT Output voltage drift 1.2 mV/°C
SVR Supply voltage rejection f = 120 Hz, I
O
= 1 A 55 61 dB
V
d
Dropout voltage I
O
= 0.5 A 200 400 mV
I
O
= 1.5 A 500 900 mV
I
sc
Short-circuit current V
I
= 14 V 2 2.7 A
Z
O
Output impedance f = 120 Hz, I
O
= 0.5 A 40 mΩ
DocID2141 Rev 14 9/25
L4940 Perfor man ce chara ct er istics
25
6 Performance characteristics
Figure 6. Dropout v oltage vs. output current Figure 7. Dropout voltage vs. temperature
Figure 8. Output voltage vs. temperature
(L4940V5) Figure 9. Output voltage vs. temperature
(L4940V85)
Figure 10. Output voltage vs. temperature
(L4940V12) Figure 11. Quiescent current vs. temperature
(L4940V5)
Performance characteristics L4940
10/25 DocID2141 Rev 14
Figure 12. Quiescent current vs. input voltage
(L4940V5) Figure 13. Quiescent current vs. output current
(L4940V5)
Figure 14. Short-cir cuit current vs. temperatur e
(L4940V5) Figure 15. Peak output current vs. input/output
differential voltage (L4940V5)
Figure 16. Low voltage behavior (L4940V5) Figure 17. Low voltage behavior (L4940V85)
DocID2141 Rev 14 11/25
L4940 Perfor man ce chara ct er istics
25
Figure 18. Low voltage behavior (L4940V12) Figure 19. Supply voltage rejection vs.
frequency (L4940V5)
Figure 20. Supply voltage rejection vs. output
current (L4940V5) Figure 21. Load dump characteristics (L4940V5)
Figure 22. Line transient response (L4940V5) Figure 23. Total power dissipation
Performance characteristics L4940
12/25 DocID2141 Rev 14
Figure 24. Load transi ent response
DocID2141 Rev 14 13/25
L4940 Application circuits
25
7
Applicati on circuits
Note: Advantages of these applications are:
On-card regulation with short-circuit and thermal protection on each output. Very high total
system efficiency due to the switching pre-regulation and very low drop post-regulation.
Figure 25. Distributed power supply with the L4960, L4940 and the L4941
Figure 26. Distributed power suppl y with the L296, L4940, and the L4941
Application circuits L4940
14/25 DocID2141 Rev 14
Note: Advantages of this configuration are:
Very high regulation (line and load on both the output voltage. 12 V output short-circuit and
thermal protection. Very high efficiency on the 12 V output due to the low drop regulator.
Figure 27. Secondary regulation for switch mode power supply with the L4940
DocID2141 Rev 14 15/25
L4940 Package information
25
8 Package information
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 information L4940
16/25 DocID2141 Rev 14
8.1 TO-220 (dual gauge) package information
Figure 28. TO-220 (dual gauge) package outline
BW\SH$B5HYB7
DocID2141 Rev 14 17/25
L4940 Package information
25
Table 7. TO-220 (dual gauge) mechanical data
Dim. mm
Min. Typ. Max.
A4.40 4.60
b0.61 0.88
b1 1.14 1.70
c0.48 0.70
D 15.25 15.75
D1 1.27
E 10 10.40
e2.40 2.70
e1 4.95 5.15
F1.23 1.32
H1 6.20 6.60
J1 2.40 2.72
L13 14
L1 3.50 3.93
L20 16.40
L30 28.90
∅
P3.75 3.85
Q2.65 2.95
Package information L4940
18/25 DocID2141 Rev 14
8.2 TO-220 (dual gauge) packing information
Figure 29. Tube for TO-220 (dual gauge) outline (mm.)
DocID2141 Rev 14 19/25
L4940 Package information
25
8.3 D²PAK package information
Figure 30. D²PAK package outline
0079457_T
Package information L4940
20/25 DocID2141 Rev 14
Table 8. D²PAK mechanical data
Dim. mm
Min. Typ. Max.
A 4.40 4.60
A1 0.03 0.23
b 0.70 0.93
b2 1.14 1.70
c 0.45 0.60
c2 1.23 1.36
D 8.95 9.35
D1 7.50
E10 10.40
E1 8.50
e2.54
e1 4.88 5.28
H15 15.85
J1 2.49 2.69
L 2.29 2.79
L1 1.27 1.40
L2 1.30 1.75
R0.4
V2 0° 8°
DocID2141 Rev 14 21/25
L4940 Package information
25
Figure 31. D²PAK recommended footprint
(a)
a. All dimensions are in millimeters.
16.90
12.20
9.75
3.50
5.08
1.60
Footprint
Package information L4940
22/25 DocID2141 Rev 14
8.4 D²PAK packi ng informat ion
Figure 32. D²PAK tape outline
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
DocID2141 Rev 14 23/25
L4940 Package information
25
Figure 33. D²PAK reel outline
Table 9. D²PAK tape and reel mechanical data
Tape Reel
Dim. mm Dim. mm
Min. Max. Min. Max.
A0 10.5 10.7 A 330
B0 15.7 15.9 B 1.5
D 1.5 1.6 C 12.8 13.2
D1 1.59 1.61 D 20.2
E 1.65 1.85 G 24.4 26.4
F 11.4 11.6 N 100
K0 4.8 5.0 T 30.4
P0 3.9 4.1
P1 11.9 12.1 Base qty 1000
P2 1.9 2.1 Bulk qty 1000
R50
T0.25 0.35
W23.7 24.3
A
D
B
Full radius G measured at hub
C
N
REEL DIMENSIONS
40mm min.
Access hole
At slot location
T
Tape slot
in core for
tape start 25 mm min.
width
AM08851v2
Revision history L4940
24/25 DocID2141 Rev 14
9 Revision history
Table 10. Document revision history
Date Revision Changes
04-Feb-2 005 6 Added new pac kage D ²PAK/A.
18-Sep-2006 7 Order codes and new template have been updated.
31-May-2007 8 Order codes have been updated.
19-Sep-2007 9 Added Table 1 to cover page.
20-Feb-2008 10 Modified: Table 1 on p ag e 1.
29-Jul-2009 11 Modified: Table 1 on page 1.
16-Dec-2009 12 Modified: Table 6 on pag e 8.
04-Nov-2013 13
The L4940XX5, L4940XX85, L4940XX10, L4940XX12 have been changed
into the L4940.
Updated: the title and the description in cover page.
Updated Section 4: Test circuits, Section 5: Electrical characteristics,
Section 6: Performance characteristics and Section 8: Package information.
Added Section 8.4: D²PAK packing information.
Minor text changes.
08-Apr-2015 14 Updated title in Table 1: De vice summary.
Updated Section 8: Package information.
Minor text changes.
DocID2141 Rev 14 25/25
L4940
25
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