參數(shù)資料
型號(hào): MAX1705EEE
廠商: MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi): 穩(wěn)壓器
英文描述: 18-Bit Universal Bus Transceivers With 3-State Outputs 56-SSOP -40 to 85
中文描述: 1.7 A SWITCHING REGULATOR, 340 kHz SWITCHING FREQ-MAX, PDSO16
封裝: 0.150 INCH, 0.025 INCH PITCH, MO-137AB, QSOP-16
文件頁(yè)數(shù): 14/20頁(yè)
文件大?。?/td> 215K
代理商: MAX1705EEE
M
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
14
______________________________________________________________________________________
The low-battery comparator can also be used to moni-
tor the output voltage, as shown in Figure 5.
To set the low-battery threshold to a voltage below the
1.25V reference, insert a resistor divider between REF
and LBN, and connect the battery to the LBP input
through a 10k
current-limiting resistor (Figure 6). The
equation for setting the resistors for the low-battery
threshold is then as follows:
Alternatively, the low-battery comparator can be used
to check the output voltage or to control the load direct-
ly on POUT during start-up (Figure 7). Use the following
equation to set the resistor values:
where V
OUT,TH
is the desired output voltage trip point
and V
LBP
is connected to the reference or 1.25V.
Referenc e
The MAX1705/MAX1706 have an internal 1.250V, 1%
bandgap reference. Connect a 0.33μF bypass capaci-
tor to GND within 0.2in. (5mm) of the REF pin. REF can
source up to 50μA of external load current.
_________________ Design Proc edure
S etting the Output V oltages
Set the step-up converter output voltage between 2.5V
and 5.5V by connecting a resistor voltage-divider to FB
from OUT to GND, as shown in Figure 8. The resistor
values are then as follows:
where V
FB
, the step-up regulator feedback setpoint, is
1.233V. Since the input bias current into FB is less than
50nA, R2 can have a large value (such as 270k
or
less) without sacrificing accuracy. Connect the resistor
voltage-divider as close to the IC as possible, within
0.2in. (5mm) of the FB pin.
Alternatively, set the step-up converter output to track
the linear regulator by 300mV. To accomplish this, set
TRACK to OUT.
R
R
V
V
POUT
FB
1
2
=
- 1
R
R
V
V
OUT TH
LBP
5
6
,
=
- 1
R
R
V
V
REF
INTH
,
5
6
=
- 1
MAX1705
MAX1706
LBO
REF
LBN
POUT
GND
R5
R6
0.33
μ
F
LDO
LBP
MAX1705
MAX1706
LBO
LBN
LBP
POUT
REF
GND
R5
R6
BATTERY
VOLTAGE
R8
10k
0.33
μ
F
270k
MAX1705
MAX1706
LBP
LBO
LBN
0.33
μ
F
OUT
POUT
REF
GND
R5
R6
P
C3
0.1
μ
F
C4
C5
STEP-UP OUTPUT
Figure 5. Using the Low-Battery Comparator to Sense
the Output Voltage
Figure 6. Detecting Battery Voltages Below 1.25V
Figure 7. Using the Low-Battery Comparator for Load Control
During Start-Up
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MAX1705EEE+ 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 1-3 Cell Step-Up w/Linear Regulator RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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(fēng)格:SMD/SMT
MAX1705EEE+T 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 1-3 Cell Step-Up w/Linear Regulator RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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(fēng)格:SMD/SMT
MAX1705EEE-T 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 1-3 Cell Step-Up w/Linear Regulator RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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(fēng)格:SMD/SMT
MAX1705ESE+ 制造商:Maxim Integrated Products 功能描述:1 TO 3-CELL HIGH-CURRENT LOW-NOIS - Rail/Tube
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