L4938ED
L4938EPD
Advanced voltage regulator
Features
■Enable and sense inputs (EN, SI) protected against negative transients down to -5 V
■Reset threshold adjustable from 3.8 V to 4.7 V
■Extremely low quiescent current, 65 µA (less than 90 µA) in standby mode
■Operating DC supply voltage range 5 V - 28 V
■Operating transient supply voltage up to 40 V
■High precision standby output voltage 5 V ± 1% with 100 mA current capability
■Output 2 voltage 5 V ± 2% with 400 mA current capability (ADJ wired to VOUT2)
■Output 2 voltage adjustable by external voltage divider
■Output 2 disable function for standby mode
SO-20 |
PowerSO-20 |
Description
The L4938ED and L4938EPD are monolithic integrated dual voltage regulators with two very low dropout outputs and additional functions such as power-on reset and input voltage sense. They are designed for supplying microcomputer controlled systems especially in automotive applications.
Table 1. |
Device summary |
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Package |
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Tube |
Tape and reel |
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SO-20 |
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L4938ED |
L4938ED013TR |
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PowerSO-20 |
L4938EPD |
L4938EPD13TR |
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March 2010 |
Doc ID 17243 Rev 1 |
1/20 |
www.st.com
Contents |
L4938ED, L4938EPD |
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Contents
1 |
Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. 5 |
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2 |
Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2.1 |
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2.2 |
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2.3 |
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3 |
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
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3.1 |
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.2 |
Standby regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
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3.3 |
Output 2 voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
12 |
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3.4 |
Reset circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
12 |
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3.5 |
Sense comparator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
13 |
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3.6 |
Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
13 |
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3.7 |
Transient sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
13 |
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3.8 |
Input protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
15 |
4 |
Package and packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
16 |
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4.1 |
ECOPACK® packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
16 |
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4.2 |
SO-20 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
16 |
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4.3 |
PowerSO-20 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
17 |
5 |
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
19 |
2/20 |
Doc ID 17243 Rev 1 |
L4938ED, L4938EPD |
List of tables |
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List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Table 2. Pin definitions and functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Table 3. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Table 4. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Table 5. OUT1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Table 6. OUT2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Table 7. OUT1, OUT2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Table 8. Enable input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Table 9. Reset circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Table 10. Sense comparator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Table 11. SO-20 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Table 12. PowerSO-20 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Table 13. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Doc ID 17243 Rev 1 |
3/20 |
List of figures |
L4938ED, L4938EPD |
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List of figures
Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 2. Configuration diagram (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 3. Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 4. OUT2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 5. Reset generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 6. Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 7. Input protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 8. Input characteristics of SI, EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 9. SO-20 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 10. PowerSO-20 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4/20 |
Doc ID 17243 Rev 1 |
L4938ED, L4938EPD |
Block diagram and pin description |
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Figure 2. |
Configuration diagram (top view) |
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PR |
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1 |
20 |
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SI |
GND |
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1 |
20 |
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GND |
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CT |
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2 |
19 |
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VS1 |
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N.C. |
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2 |
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N.C. |
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EN |
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3 |
18 |
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VS2 |
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VS2 |
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3 |
18 |
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OUT2 |
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GND |
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4 |
17 |
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GND |
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VS1 |
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4 |
17 |
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ADJ |
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GND |
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5 |
16 |
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GND |
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SI |
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5 |
16 |
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OUT1 |
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GND |
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6 |
15 |
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GND |
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PR |
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6 |
15 |
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SO |
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GND |
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7 |
14 |
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GND |
CT |
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7 |
14 |
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RESET |
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RES |
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13 |
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N.C. |
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EN |
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SO |
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12 |
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OUT2 |
N.C. |
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N.C. |
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OUT1 |
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10 |
11 |
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ADJ |
GND |
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10 |
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GND |
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PowerSO-20 |
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SO-20 |
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Doc ID 17243 Rev 1 |
5/20 |
Block diagram and pin description |
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L4938ED, L4938EPD |
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Table 2. |
Pin definitions and functions |
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PIn number |
Name |
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Function |
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SO-20 |
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PowerSO-20 |
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18 |
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3 |
VS2 |
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Supply voltage (400 mA regulator) |
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19 |
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4 |
VS1 |
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Supply voltage (100 mA regulator, reset, sense) |
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20 |
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5 |
SI |
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Sense input |
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1 |
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6 |
PR |
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Reset threshold programming |
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2 |
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7 |
CT |
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Reset delay capacitor |
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3 |
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8 |
EN |
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Enable (low activates the 400 mA regulator) |
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4, 5, 6, 7, 14, 15, |
1, 10, 11, 20 |
GND |
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Ground |
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16, 17 |
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8 |
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14 |
RES |
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Reset output |
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9 |
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15 |
SO |
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Sense output |
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10 |
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16 |
OUT1 |
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100 mA regulator output |
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11 |
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17 |
ADJ |
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Feedback of 400 mA regulator |
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12 |
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18 |
OUT2 |
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400 mA regulator output |
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13 |
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2, 9, 19 |
NC |
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Not connected |
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6/20 |
Doc ID 17243 Rev 1 |