LM5080MM/NOPB National Semiconductor, LM5080MM/NOPB Datasheet - Page 11

• Manufacturer Part Number: LM5080MM/NOPB
• Description: IC CONTROLLER LOAD SHARE 8-MSOP
• Manufacturer: National Semiconductor

Specifications of LM5080MM/NOPB

• Applications: Power Supplies, Converters, Controllers
• Current - Supply: 3.7mA
• Voltage - Supply: 3 V ~ 14 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM5080MM; LM5080MMTR

Voltage Margining
Shifting the output regulation voltage up or down by a small
amount is referred to as voltage margining. In the remote
sense adjust modes and the feedback adjust modes, this
can be done by connecting all of the power converter TRIM
pins together and injecting a positive or negative current.
However, in the reference adjust mode, the TRIM pin is used
for current sharing. An alternative margining method is to
inject a current into the SHR share bus. This will simulta-
neously shift the regulation voltages of all power converter’s
while maintaining equal current sharing. The injected current
is split equally between the LM5080’s SHR inputs and added
to the TRIM pin currents creating an equal offset voltage for
all of the power converter references. The trim pin current
injected into each power converter’s reference (IT) is depen-
dent on the magnitude of the total injected current into the
SHR bus (ISHR), the number of LM5080’s on the SHR bus
(N) and any transconductance boost supplied (R1 & R2):
FIGURE 6. One Method of Implementing Voltage Margining
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An alternate method to shift the regulation voltage is to tie all
the CSP pins together and inject a current into that node.
The trim pin current injected into each power converter’s
reference (IT) attributed to the current injected into the CSP
node (ICSP) is derived to be:
Figure 6 shows a margining up and down application imple-
mented using pull up resistors to VCC. Since the SHR and
CSP voltages are approximately 0.1 x VCC and 0.2 x VCC
respectively, the injected current can be independently con-
trolled with RM1 and RM2.
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