- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄98169 > TC2575-12.0VAT 3.2 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5 PDF資料下載
參數(shù)資料
| 型號： | TC2575-12.0VAT |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3.2 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5 |
| 封裝： | TO-220, 5 PIN |
| 文件頁數(shù)： | 9/26頁 |
| 文件大小： | 172K |
| 代理商： | TC2575-12.0VAT |
17
TC2575
TC2575-1 3/13/00
1.0A Step-Down Switching Regulator
2001 Microchip Technology Inc.
DS21398A
ADDITIONAL APPLICATIONS
Inverting Regulator
An inverting buck–boost regulator using the TC2575
(12V) is shown in Figure 8. This circuit converts a positive
input voltage to a negative output voltage with a common
ground by bootstrapping the regulators ground to the
negative output voltage. By grounding the feedback pin,
the regulator senses the inverted output voltage and regu-
lates it.
In this example the TC2575 (12V) is used to generate a
12V output. The maximum input voltage in this case cannot
exceed 28V because the maximum voltage appearing
across the regulator is the absolute sum of the input and
output voltages and this must be limited to a maximum of
40V.
This circuit configuration is able to deliver approximately
0.35A to the output when the input voltage is 12V or higher.
At lighter loads the minimum input voltage required drops to
approximately 4.7V, because the buck–boost regulator to-
pology can produce an output voltage that, in its absolute
value, is either greater or less than the input voltage.
Since the switch currents in this buck–boost configura-
tion are higher than in the standard buck converter topology,
the available output current is lower.
This type of buck–boost inverting regulator can also
require a larger amount of startup input current, even for light
loads. This may overload an input power source with a
current limit less than 1.5A.
Such an amount of input start-up current is needed for
at least 2.0msec or more. The actual time depends on the
output voltage and size of the output capacitor.
Because of the relatively high startup currents required
by this inverting regulator topology, the use of a delayed
startup or an undervoltage lockout circuit is recommended.
Using a delayed startup arrangement, the input capaci-
tor can charge up to a higher voltage before the switch–
mode regulator begins to operate.
The high input current needed for startup is now partially
supplied by the input capacitor CIN.
Design Recommendations:
The inverting regulator operates in a different manner
than the buck converter and so a different design procedure
has to be used to select the inductor L1 or the output
capacitor COUT.
The output capacitor values must be larger than what is
normally required for buck converter designs. Low input
voltages or high output currents require a large value output
capacitor (in the range of thousands of
F).
The recommended range of inductor values for the
inverting converter design is between 68
H and 220 H. To
select an inductor with an appropriate current rating, the
inductor peak current has to be calculated.
The following formula is used to obtain the peak inductor
current:
IPEAK ≈
ILOAD (VIN – IVOUTI)
+
VIN x tON
VIN
2L1
where tON ≈
IVOUTI
1.0
, and fOSC = 52kHz.
VIN + IVOUTI
x
fOSC
Under normal continuous inductor current operating
conditions, the worst case occurs when VIN is minimal.
Note that the voltage appearing across the regulator is
the absolute sum of the input and output voltage, and must
not exceed 40V.
It has been already mentioned above, that in some
situations, the delayed startup or the undervoltge lockout
features could be very useful. A delayed startup circuit
applied to a buck-boost converter is shown in Figure 9.
Figure 15 in the "Undervoltage Lockout" section describes
an undervoltage lockout feature for the same converter
topology.
Figure 9. Inverting Buck-Boost Regulator with Delayed Startup
D1
1N5819
L1
100
H
Output
GND
2
3
4
Feedback
12 to 25V
Unregulated
DC Input
1
C1
0.1
F
5
R1
47k
R2
47k
ON/OFF
+VIN
–12V @ 0.35A
Regulated
Output
TC2575
(12V)
COUT
1800
F/16V
CIN
100
F
/50V
TC2575
1
3
5
GND
ON/OFF
+VIN
R2
47k
CIN
100
F
NOTE: This picture does not show the complete circuit.
R1
47 k
R3
470
Shutdown
Input
MOC8101
–VOUT
Off
On
5.0V
+VIN
Figure 10. Inverting Buck-Boost Regulator Shutdown
Circuit Using an Optocoupler
相關PDF資料 |
PDF描述 |
|---|---|
| TC271-40 | SPECIALTY ANALOG CIRCUIT, CDIP22 |
| TC33025VOETR | 2 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| TC33163EOETR | 3.4 A SWITCHING CONTROLLER, 55 kHz SWITCHING FREQ-MAX, PDSO16 |
| TC33163EOETR | 3.4 A SWITCHING REGULATOR, 55 kHz SWITCHING FREQ-MAX, PDSO16 |
| TC3400VOART | 2-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PDSO8 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| TC2575-3.3VAT | 制造商:TELCOM 制造商全稱:TelCom Semiconductor, Inc 功能描述:1.0A Step-Down Switching Regulator |
| TC2575-5.0VAT | 制造商:TELCOM 制造商全稱:TelCom Semiconductor, Inc 功能描述:1.0A Step-Down Switching Regulator |
| TC2575VAT | 制造商:TELCOM 制造商全稱:TelCom Semiconductor, Inc 功能描述:1.0A Step-Down Switching Regulator |
| TC258 | 制造商:MCM 功能描述:6FT DC POWER CORD STRAIGHT 2.5X5.5 18 AWG |
| TC258B | 制造商:Datak Corporation 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復。