LM2576T-012 ON Semiconductor, LM2576T-012 Datasheet - Page 11
![IC REG SW 3A 12V STEPDWN TO220-5](/photos/36/39/363974/to220-5_sml.jpg)
LM2576T-012
Manufacturer Part Number
LM2576T-012
Description
IC REG SW 3A 12V STEPDWN TO220-5
Manufacturer
ON Semiconductor
Type
Step-Down (Buck)r
Datasheet
1.LM2576D2T-ADJR4G.pdf
(28 pages)
Specifications of LM2576T-012
Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
12V
Current - Output
3A
Frequency - Switching
52kHz
Voltage - Input
7 ~ 40 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Through Hole
Package / Case
TO-220-5 (Straight Leads)
Mounting Style
Through Hole
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LM2576T-012G
Manufacturer:
ON Semiconductor
Quantity:
2 000
Procedure (Fixed Output Voltage Version) (continued)In order to simplify the switching regulator design, a step−by−step
design procedure and some examples are provided.
Procedure (Adjustable Output Version: LM2576−ADJ)
5. Output Capacitor Selection (C
Given Parameters:
1. Programming Output Voltage
2. Input Capacitor Selection (C
3. Catch Diode Selection (D1)
A. Since the LM2576 is a forward−mode switching regulator
B. Due to the fact that the higher voltage electrolytic capacitors
V
V
I
To select the right programming resistor R1 and R2 value (see
Figure 2) use the following formula:
Resistor R1 can be between 1.0 k and 5.0 kW. (For best
temperature coefficient and stability with time, use 1% metal
film resistors).
To prevent large voltage transients from appearing at the input
and for stable operation of the converter, an aluminium or
tantalum electrolytic bypass capacitor is needed between the
input pin +V
located close to the IC using short leads. This capacitor should
have a low ESR (Equivalent Series Resistance) value.
For additional information see input capacitor section in the
“Application Hints” section of this data sheet.
A. Since the diode maximum peak current exceeds the
B. The reverse voltage rating of the diode should be at least
Load(max)
out
in(max)
with voltage mode control, its open loop 2−pole−1−zero
frequency characteristic has the dominant pole−pair
determined by the output capacitor and inductor values. For
stable operation and an acceptable ripple voltage,
(approximately 1% of the output voltage) a value between
680 mF and 2000 mF is recommended.
generally have lower ESR (Equivalent Series Resistance)
numbers, the output capacitor’s voltage rating should be at
least 1.5 times greater than the output voltage. For a 5.0 V
regulator, a rating at least 8.0 V is appropriate, and a 10 V or
16 V rating is recommended.
regulator maximum load current the catch diode current
rating must be at least 1.2 times greater than the maximum
load current. For a robust design, the diode should have a
current rating equal to the maximum current limit of the
LM2576 to be able to withstand a continuous output short.
1.25 times the maximum input voltage.
= Regulated Output Voltage
V out + V
= Maximum DC Input Voltage
= Maximum Load Current
in
and ground pin GND This capacitor should be
ref
R2 + R1
1.0 )
Procedure
Procedure
R2
R1
V out
V
in
ref
)
out
where V
– 1.0
)
ref
= 1.23 V
http://onsemi.com
LM2576
11
5. Output Capacitor Selection (C
Given Parameters:
1. Programming Output Voltage (selecting R1 and R2)
2. Input Capacitor Selection (C
the input and ground pin provides sufficient bypassing.
3. Catch Diode Selection (D1)
A. C
B. Capacitor voltage rating = 20 V.
V
V
I
Select R1 and R2:
A 100 mF, 150 V aluminium electrolytic capacitor located near
A. For this example, a 3.0 A current rating is adequate.
B. Use a 30 V 1N5821 Schottky diode or any suggested fast
Load(max)
out
in(max)
R2 = 9.91 kW, choose a 9.88 k metal film resistor.
recovery diode in the Table 1.
out
= 8.0 V
V out + 1.23 1.0 )
R2 + R1
= 680 mF to 2000 mF standard aluminium electrolytic.
= 25 V
= 2.5 A
V out
V
ref
* 1.0
Example
Example
R2
R1
in
)
out
+ 1.8 k
Select R1 = 1.8 kW
)
1.23 V
8.0 V
* 1.0