參數(shù)資料
型號： MAX1672EEE
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： Step-Up/Down DC-DC Converter in QSOP Package
中文描述： 1.1 A SWITCHING REGULATOR, PDSO16
封裝： 0.150 INCH, QSOP-16
文件頁數(shù)： 8/12頁
文件大小： 143K
代理商： MAX1672EEE
M
S tep-Up/Down DC-DC Converter
in QS OP Pac kage
8
_______________________________________________________________________________________
__________________Design Proc edure
Output V oltage S elec tion
For fixed output voltages of 3.3V or 5V, connect 3/
5
to
PS or GND and connect FB to GND (Table 2).
Alternatively, adjust the output voltage from 1.25V to
5.5V by connecting two resistors, R1 and R2 (Figure 2),
which form a voltage divider between OUT and FB.
Choose resistor values as follows:
R1 = R2[(V
OUT
/ V
REF
) -1]
where V
REF
= 1.25V. Since the input bias current at FB
has a maximum value of 50nA, R1 and R2 can be large
with no significant accuracy loss. Choose R2 in the
100k
to 270k
range and calculate R1 using the
above formula. For 1% error, the current through R1
should be at least 100 times FB’s bias current.
Whenever the voltage at FB exceeds 70mV above
GND, the state of the 3/
5
pin is ignored. Connect 3/
5
to
GND when adjusting V
OUT
with a resistor divider. Never
leave 3/
5
unconnected.
Low-Battery Detec tion
The MAX1672 contains a comparator for low-battery
detection. If the voltage at PGI falls below V
REF
(typical-
ly 1.25V), the open-drain comparator output (
PGO
)
goes high. Hysteresis is typically 30mV. Set the low-
battery detector’s threshold with resistors R3 and R4
(Figure 2) using the following equation:
R3 = R4[(V
PGT
/ V
REF
) -1]
where V
PGT
is the desired threshold of the low-battery
detector and V
REF
= 1.25V. Since the input bias current
at PGI has a maximum value of 50nA, R3 and R4 can
be large to minimize input loading with no significant
accuracy loss. Choose R4 in the 100k
to 270k
range
and calculate R3 using the above formula. For 1%
error, the current through R3 should be at least 100
times PGI’s bias current.
The
PGO
output is open-drain and should be pulled
high with external resistor R5 for normal operation. If the
low-battery comparator is not used, connect PGI and
PGO
to GND.
Induc tor S elec tion
A 10μH inductor performs well in most MAX1672 appli-
cations. Smaller inductor values typically offer a smaller
physical size for a given series resistance, but may
increase switching losses. Larger inductor values
exhibit higher output current capability and larger phys-
ical dimensions for a given series resistance. For opti-
mum performance, choose an inductor value from
Table 3 or by using the following equation:
(
where I
LIM
is the peak switch-current limit, which is
0.8A for I
LIM
= PS and 0.5A for I
LIM
= GND.
The inductor’s incremental saturation current rating
should also be greater than the peak switch-current
limit. However, it is generally acceptable to bias most
inductors into saturation by as much as 20% with slight-
ly reduced efficiency. The inductor’s DC resistance sig-
nificantly affects efficiency. See Tables 4 and 5 for a list
of suggested inductors and suppliers.
V
+ V
I
LIM
V
+ V
I
OUT
DIODE
IN(min)
SWITCH
LIM
)
<
<
(
)
t
L
t
OFF
ON
2
(max)
MAX1672
IN
ONA
ONB
3/5
PGI
OFF
OFF
ON
C3
0.1
μ
F
C1
100
μ
F
C2
100
μ
F
R2
R1
R5
1M
C4
4.7
μ
F
R3
R4
L1
10
μ
H
PGND
GND
PS
1.25V TO
5.5V OUTPUT
INPUT
1.8V TO11V
LOW-BATTERY-
DETECTOR
OUTPUT
OUT
PG0
FB
REF
LX
ILIM
0.8A
ON
0.5A
Figure 2. Adjustable Output Voltage Configuration
Table 2. Output Voltage Control
FB
V
OUT
(V)
0
GND
+5
1
GND
+3.3
3/
5
X
>70mV
+1.25 to +5.5
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MAX1672EEE+ 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up/Down RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
MAX1672EEE+T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up/Down RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
MAX1672EEE-T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up/Down RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
MAX1672EVKIT 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Evaluation Kit for the MAX1672 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
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