LM2611BMF/NOPB National Semiconductor, LM2611BMF/NOPB Datasheet - Page 12

• Manufacturer Part Number: LM2611BMF/NOPB
• Description: IC CONVERTER CUK SOT-23-5
• Manufacturer: National Semiconductor
• Type: Cukr

Specifications of LM2611BMF/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: Adj to -36V
• Current - Output: 300mA
• Frequency - Switching: 1.4MHz
• Voltage - Input: 2.7 ~ 14 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Power - Output: 2W
• Primary Input Voltage: 5V
• No. Of Outputs: 1
• Output Voltage: -36V
• Output Current: 1A
• No. Of Pins: 5
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Filter Terminals: SMD
• Rohs Compliant: Yes
• For Use With: LM2611EVAL - BOARD EVALUATION LM2611
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM2611BMF; LM2611BMFTR

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Application Circuits
Split Supply Operation
The LM2611 may be operated with separate power and bias
supplies. In the circuit shown in Figure 12. V
supply that the regulated voltage is derived from, and V
a low current supply used to bias the LM2611. Conditions for
the supplies are:
As the input voltage increases, the maximum output current
capacbility increases. Using a separate, higher voltage sup-
ply for power conversion enables the LM2611 to provide
higher output currents than it would with a single supply that
is limited in voltage by V
0V ≤ V
2.7V ≤ V
IN
FIGURE 12. LM2611 Operating with Separate Power and Biasing Supplies
IN(MAX)
≤ (36 - IV
DD
.
≤ 14V
OUT
(Continued)
I) V
IN
is the power
DD
is
12
Shutdown/Soft Start
A soft start circuit is used in switching power supplies to limit
the input inrush current upon start-up. Without a soft-start
circuit, the inrush current can be several times the steady-
state load current, and thus apply unnecessary stress to the
input source. The LM2611 does not have soft-start circuitry,
but implementing the circuit in Figure 13 will lower the peak
inrush current. The SHDN pin is coupled to the output
through C
run states while the output slowly decreases to its steady-
state value. The energy required to reach steady-state is
spread over a longer time and the input current spikes
decrease (see Figure 14 and Figure 15).
SS
. The LM2611 is toggled between shutdown and
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