LMS1587IS-ADJ National Semiconductor, LMS1587IS-ADJ Datasheet - Page 6

• Manufacturer Part Number: LMS1587IS-ADJ
• Description: IC REG LDO FAST RESPONSE TO-263
• Manufacturer: National Semiconductor

Specifications of LMS1587IS-ADJ

• Regulator Topology: Positive Adjustable
• Voltage - Output: 1.25 ~ 5.7 V
• Voltage - Input: 2.5 ~ 13 V
• Voltage - Dropout (typical): 1.15V @ 3A
• Number Of Regulators: 1
• Current - Output: 3A
• Current - Limit (min): 3.1A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-3, D²Pak (3 leads + Tab), TO-263AA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LMS1587IS-ADJ

Application Note
OUTPUT VOLTAGE
The adjustable version develops at 1.25V reference voltage,
(V
), between the output and the adjust terminal. As
REF
shown in Figure 1, this voltage is applied across resistor R1
to generate a constant current I1. This constant current then
flows through R2. The resulting voltage drop across R2 adds
to the reference voltage to sets the desired output voltage.
The current I
from the adjustment terminal introduces an
ADJ
output error. But since it is small (120µA max), it becomes
negligible when R1 is in the 100Ω range.
For fixed voltage devices, R1 and R2 are integrated inside
the devices.
10119772
FIGURE 1. Basic Adjustable Regulator
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