LM2640MTC-ADJ National Semiconductor, LM2640MTC-ADJ Datasheet - Page 8

• Manufacturer Part Number: LM2640MTC-ADJ
• Description: Dual Adjustable Step-Down Switching Power Supply Controller
• Manufacturer: National Semiconductor

Electrical Characteristics
(Continued)
Note 8: Both controllers are ON but not switching. Currents entering the IC at IN, CSL1, CSH1, CSL2, and CSH2 are measured. Those entering at CSL1 and CSH1
are multiplied by 0.50 to emulate the effect of a switching conversion from 10V down to 5V. Those entering at CSL2 and CSH2 are multiplied by 0.33 to emulate
the effect of a switching conversion from 10V down to 3.3V. After multiplication, all five currents are added. Because the voltage at the CSL1 input is greater than
the LIN-to-V
switchover threshold, most of the input supply current enters the IC via the CSL1 input.
OUT
Note 9: Both switching controllers are OFF. The 5V, 50 mA linear regulator (output at LIN) and the precision 2.5V reference (output at REF) remain ON.
Note 10: Both switching controllers and the 2.5V precision reference are OFF. The 5V, 50 mA linear regulator remains ON.
Note 11: The controllers remain OFF until the voltage of the 5V, 50 mA linear regulator (output at LIN) reaches this threshold.
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