參數(shù)資料
型號: MAX1724
廠商: Maxim Integrated Products, Inc.
元件分類: 數(shù)字信號處理
英文描述: Replaced by TMS320VC5506 : Digital Signal Processors 132-BQFP -40 to 85
中文描述: 1.5µA IQ、升壓型DC-DC轉換器,薄型SOT23-5封裝
文件頁數(shù): 9/12頁
文件大?。?/td> 292K
代理商: MAX1724
M
1.5μA I
Q
, Step-Up DC-DC Converters
in Thin SOT23-5
_______________________________________________________________________________________
9
Inductor Selection
The control scheme of the MAX1722/MAX1723/
MAX1724 permits flexibility in choosing an inductor. A
10μH inductor value performs well in most applications.
Smaller inductance values typically offer smaller physi-
cal size for a given series resistance, allowing the
smallest overall circuit dimensions. Circuits using larger
inductance values may start up at lower battery volt-
ages, provide higher efficiency, and exhibit less ripple,
but they may reduce the maximum output current. This
occurs when the inductance is sufficiently large to pre-
vent the maximum current limit (I
LIM
) from being
reached before the maximum on-time (t
ON(MAX)
)
expires.
Table 1. Suggested Inductors and
Suppliers
For maximum output current, choose the inductor value
so that the controller reaches the current-limit before
the maximum on-time is triggered:
where the maximum on-time is typically 5μs, and the
current limit (I
LIM
) is typically 500mA (see
Electrical
Characteristics
table).
For larger inductor values, determine the peak inductor
current (I
PEAK)
by:
The inductor
s incremental saturation current rating should
be greater than the peak switching current. However, it is
generally acceptable to bias the inductor into saturation
by as much as 20%, although this will slightly reduce effi-
ciency. Table 1 lists suggested inductors and suppliers.
Maximum Output Current
The maximum output current depends on the peak induc-
tor current, the input voltage, the output voltage, and the
overall efficiency (
η
):
I
I
V
V
OUT MAX
(
PEAK
BATT
OUT
)
=
1
2
η
I
V
L
PEAK
BATT ON MAX
=
(
)
L
V
I
BATT ON MAX
LIM
<
(
)
MAX1724
GND
BATT
OUTPUT
V
OUT (NOM)
INPUT
0.8V TO V
OUT
10
μ
H
C2
10
μ
F
SHDN
LX
OUT
C1
10
μ
F
OFF
ON
Figure 8. MAX1724 Standard Application Circuit
MAX1722
GND
BATT
OUTPUT
2V TO 5.5V
INPUT
0.8V TO V
OUT
10
μ
H
LX
OUT
FB
R2
10
μ
F
R1
10
μ
F
Figure 7. Adjustable Output Circuit
MANUFACTURER
INDUCTOR
PHONE
WEBSITE
Coilcraft
DO1608 Series
DO1606 Series
847-639-2361
www.coilcraft.com
Murata
LQH4C Series
770-436-1300
www.murata.com
Sumida
CDRH4D18 Series
CR32 Series
CMD4D06 Series
847-545-6700
www.sumida.com
Sumitomo/
Daidoo Electronics
CXLD140 Series
+81 (06) 6355-5733
www.daidoo.co.jp
Toko
3DF Type
D412F Type
847-297-0070
www.toko.com
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