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參數(shù)資料
| 型號(hào)： | ML4870CS-3 |
| 英文描述： | High Current Boost Regulator with Load Disconnect |
| 中文描述： | 高電流升壓穩(wěn)壓器與負(fù)載斷開 |
| 文件頁數(shù)： | 7/8頁 |
| 文件大?。?/td> | 211K |
| 代理商： | ML4870CS-3 |
ML4870
7
INPUT CAPACITOR
Due to the high input current drawn at startup and
possibly during operation, it is recommended to decouple
the input with a capacitor with a value of 47μF to 100μF.
This filtering prevents the input ripple from affecting the
ML4870 control circuitry, and also improves the
efficiency by reducing the I
2
R losses during the charge
cycle of the inductor. Again, a low ESR capacitor (such as
tantalum) is recommended.
It is also recommended that low source impedance
batteries be used. Otherwise, the voltage drop across the
source impedance during high input current situations will
cause the ML4870 to fail to start-up or to operate
unreliably. In general, for two cell applications the source
impedance should be less than 200m
W
, which means that
small alkaline cells should be avoided.
SHUTDOWN
The input levels of the SHDN pin are CMOS compatible.
To guarantee proper operation, SHDN must be pulled to
within 0.5V of GND or V
IN
to prevent excessive power
dissipation and possible oscillations. A graph of input
leakage current while in shudown is shown in Figure 6.
LAYOUT
Good layout practices will ensure the proper operation of
the ML4870. Some layout guidelines follow:
Use adequate ground and power traces or planes
Keep components as close as possible to the ML4870
Use short trace lengths from the inductor to the V
L1
and
V
L2
pins and from the output capacitor to the V
OUT
pin
Use a single point ground for the ML4870 PWR GND
pin and the input and output capacitors, and connect
the GND pin to PWR GND using a separate trace
Separate the ground for the converter circuitry from the
ground of the load circuitry and connect at a single
point
Figure 8. Design Example Schematic Diagram
DEISGN CONSIDERATIONS
(Continued)
DESIGN EXAMPLE
In order to design a boost converter using the ML4870,
it is necessary to define the values of a few parameters.
For this example, we have assumed that V
IN
= 3.0V to
3.6V, V
OUT
= 5.0V, and I
OUT(MAX)
= 400mA
First, it must be determined whether the ML4870 is
capable of delivering the output current. This is done
using Equation 1:
I
V
V
mA
OUT MAX
(
)
.
.
.
.
=
-
=
0972
30
50
0144
439
Next, select an inductor:
As previously mentioned, it is the recommended
inductance is 10μH. Make sure that the peak current
rating of the inductor is at least 1.5A, and that the DC
resistance of the inductor is in the range of 50 to 100m
W
.
Finally, the value of the output capacitor is determined
using Equation 3:
C
H
V
F
OUT
=
50
.
=
44
10
88
m
m
The closest standard value would be a 100μF capacitor
with an ESR rating of 100m
W
. If such a low ESR value
cannot be found, two 47μF capacitors in parallel could
also be used.
The complete circuit is shown in Figure 8. As mentioned
previously, the use of an input supply bypass capacitor is
strongly recommended.
ML4870
VOUT
100μF
100μF
VIN
10μH
(SUMIDA CD75)
VL1
VIN
GND
SHDN
PWR GND
NC
VL2
VOUT
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ML4870ES-3 | High Current Boost Regulator with Load Disconnect |
| ML4870ES-5 | High Current Boost Regulator with Load Disconnect |
| ML4871CS-3 | High Current Boost Regulator |
| ML4890CS-3 | High Efficiency, Low Ripple Boost Regulator |
| ML4890ES-3 | High Efficiency, Low Ripple Boost Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4870CS-5 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Current Boost Regulator with Load Disconnect |
| ML4870ES-3 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Current Boost Regulator with Load Disconnect |
| ML4870ES-5 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Current Boost Regulator with Load Disconnect |
| ML4871 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Current Boost Regulator |
| ML4871CS3 | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Fairchild Semiconductor Corporation 功能描述: |
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