LM2670S-ADJ/NOPB National Semiconductor, LM2670S-ADJ/NOPB Datasheet - Page 7

• Manufacturer Part Number: LM2670S-ADJ/NOPB
• Description: IC REG SIMPLE SWITCHER TO-263-7
• Manufacturer: National Semiconductor
• Series: SIMPLE SWITCHER®r
• Type: Step-Down (Buck)r

Specifications of LM2670S-ADJ/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.2 ~ 37 V
• Current - Output: 3A
• Frequency - Switching: 260kHz
• Voltage - Input: 8 ~ 40 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: D²Pak, TO-263 (7 leads + tab)
• Primary Input Voltage: 40V
• No. Of Outputs: 1
• Output Voltage: 37V
• Output Current: 3A
• No. Of Pins: 7
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 3 - 168 Hours
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Other names: *LM2670S-ADJ; *LM2670S-ADJ/NOPB; LM2670S-ADJ

Other Applications
PARALLELING DEVICES
Any number of LM2664s can be paralleled to reduce the
output resistance. Each device must have its own pumping
capacitor C
as shown in Figure 3. The composite output resistance is:
CASCADING DEVICES
Cascading the LM2664s is an easy way to produce a greater
negative voltage (e.g. A two-stage cascade circuit is shown
in Figure 4).
If n is the integer representing the number of devices cas-
caded, the unloaded output voltage V
fective output resistance is equal to the weighted sum of
each individual device:
COMBINED DOUBLER AND INVERTER
In Figure 5, the LM2664 is used to provide a positive voltage
doubler and a negative voltage converter. Note that the total
current drawn from the two outputs should not exceed 50
mA.
1
, while only one output capacitor C
FIGURE 3. Lowering Output Resistance by Paralleling Devices
FIGURE 4. Increasing Output Voltage by Cascading Devices
out
is (-nV
out
in
is needed
). The ef-
7
Note that, the number of n is practically limited since the
increasing of n significantly reduces the efficiency, and in-
creases the output resistance and output voltage ripple.
R
out
= nR
out_1
+ n/2 R
out_2
10003110
+ ... + R
10003111
out_n
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