LM2675M-3.3/NOPB National Semiconductor, LM2675M-3.3/NOPB Datasheet - Page 17

• Manufacturer Part Number: LM2675M-3.3/NOPB
• Description: IC REG SIMPLE SWITCHER 8-SOIC
• Manufacturer: National Semiconductor
• Series: SIMPLE SWITCHER®r
• Type: Step-Down (Buck)r

Specifications of LM2675M-3.3/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 3.3V
• Current - Output: 1A
• Frequency - Switching: 260kHz
• Voltage - Input: 6.5 ~ 40 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Package: 8SOIC N
• Minimum Input Voltage: 8 V
• Maximum Input Voltage: 40 V
• Switching Frequency: 260(Typ) KHz
• Operating Supply Voltage: 6.5 to 40 V
• Maximum Output Current: 1 A
• Output Type: Fixed
• Output Voltage: 3.3 V
• Efficiency: 86(Typ) %
• Primary Input Voltage: 12V
• No. Of Outputs: 1
• Output Current: 1A
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Filter Terminals: SMD
• Rohs Compliant: Yes
• For Use With: LM2675-5.0EVAL - EVALUATION BOARD FOR LM2675-5.0
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Other names: *LM2675M-3.3; *LM2675M-3.3/NOPB; LM2675M-3.3

To simplify the buck regulator design procedure, National
Semiconductor is making available computer design software to
be used with the SIMPLE SWITCHER line of switching
regulators. LM267X Made Simple version 6.0 is available for
use on Windows 3.1, NT, or 95 operating systems.
Given:
1. Programming Output Voltage (Selecting R
shown in Figure 3)
Use the following formula to select the appropriate resistor
values.
Select a value for R
resistor values minimize noise pickup in the sensitive feedback
pin. (For the lowest temperature coefficient and the best stability
with time, use 1% metal film resistors.)
where V
LM2675 Series Buck Regulator Design Procedure (Fixed Output)
LM2675 Series Buck Regulator Design Procedure (Adjustable Output)
V
V
I
F = Switching Frequency (Fixed at a nominal 260 kHz).
LOAD
OUT
IN
(max) = Maximum Input Voltage
PROCEDURE (Adjustable Output Voltage Version)
(max) = Maximum Load Current
= Regulated Output Voltage
REF
= 1.21V
1
between 240Ω and 1.5 kΩ. The lower
Recommended
Application Voltage
Recommended
Application Voltage
1
and R
2
3.3
2.5
3.3
10
12
15
12
18
24
29
, as
5
5
8
Sprague 594D
+85˚C Rating
+85˚C Rating
FIGURE 15.
AVX TPS
17
Given:
1. Programming Output Voltage (Selecting R
shown in Figure 3)
Select R
R
R
2
2
V
V
I
F = Switching Frequency (Fixed at a nominal 260 kHz).
LOAD
= 1k (16.53 − 1) = 15.53 kΩ, closest 1% value is 15.4 kΩ.
= 15.4 kΩ.
OUT
IN
Voltage
Rating
Voltage
Rating
(max) = 28V
EXAMPLE (Adjustable Output Voltage Version)
(max) = 1A
= 20V
1
to be 1 kΩ, 1%. Solve for R
6.3
6.3
10
20
25
35
10
16
20
25
35
50
4
2
.
1
(Continued)
and R
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2
, as