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參數(shù)資料
| 型號(hào)： | ML4950 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Adjustable Output, Low Current Single Cell Boost Regulator with Detect(帶低電檢測(cè)電路的輸出可調(diào)、低電流單節(jié)電池上電升壓穩(wěn)壓器) |
| 中文描述： | 可調(diào)輸出，低電流的單電池升壓穩(wěn)壓器與檢測(cè)（帶低電檢測(cè)電路的輸出可調(diào)，低電流單節(jié)電池上電升壓穩(wěn)壓器） |
| 文件頁(yè)數(shù)： | 8/10頁(yè) |
| 文件大?。?/td> | 284K |
| 代理商： | ML4950 |
ML4950
8
It is important to note that the accuracy of these resistors
directly affects the accuracy of the output voltage. The
SENSE pin threshold variation is ±3%, and the tolerance of
R
1
and R
2
will add to this to determine the total output
variation.
Under some circumstances, input ripple cannot be
reduced effectively. This occurs primarily in applications
where inductor currents are high, causing excess output
ripple due to “pulse grouping”, where the charge-
discharge pulses are not evenly spaced in time. In such
cases it may be necessary to add a small 20pF to 100pF
ceramic feedforward capacitor (C
FF
) from the V
IN
pin to
the SENSE pin. This is particularly true if the ripple voltage
at V
IN
is greater than 100mV.
SETTING THE
RESET
THRESHOLD
To use the
RESET
comparator as an input voltage monitor,
it is necessary to use an external resistor divider tied to the
DETECT pin as shown in Figure 7. The resistor values R
A
and R
B
can be calculated using the following equation:
02
1
6
V
R
R
R
IN MIN
(
A
B
B
)
.
=
+
(7)
The value of R
B
should be 100k
W
or less to minimize bias
current errors. R
A
is then found by rearranging the
equation:
R
R
V
A
B
IN MIN
(
.2
=
-
)
1
(8)
LAYOUT
Good PC board layout practices will ensure the proper
operation of the ML4950. Important layout considerations
include:
I
Use adequate ground and power traces or planes
I
Keep components as close as possible to the ML4950
I
Use short trace lengths from the inductor to the V
L
pin
and from the output capacitor to the V
OUT
pin
I
Use a single point ground for the ML4950 PWR GND
pin and the input and output capacitors, and connect
GND to PWR GND with a separate trace
A typical PC board layout is shown in Figure 8.
DESIGN CONSIDERATIONS
(Continued)
Figure 8. Typical PC Board Layout
Figure 6. No Load Input Current vs. V
IN
For 2V R1 = 365k
W
, R2 = 40.2k
W
For 3V R1 = 562k
W
, R2 = 40.2k
W
L = Sumida CD43, 22μH
80
60
40
20
0
I
VIN (V)
1.0
1.5
2.0
3.0
2.5
2V OUTPUT
3V OUTPUT
Figure 7. Battery Monitoring Circuit
VIN
RA
RB
1
DETECT
4
RESET
VREF
FROM
START-UP
CIRCUITRY
+
COMP
–
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4950 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML4950CS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ML4950ES | 制造商:MICRO-LINEAR 制造商全稱(chēng):MICRO-LINEAR 功能描述:Adjustable Output, Low Current Single Cell Boost Regulator with Detect |
| ML4961 | 制造商:MICRO-LINEAR 制造商全稱(chēng):MICRO-LINEAR 功能描述:Adjustable Output Low Voltage Boost Regulator with Detect |
| ML4961CS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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