參數(shù)資料
型號(hào)： MAX1965
廠商： Maxim Integrated Products, Inc.
英文描述： Tracking/Sequencing Triple/Quintuple Power-Supply Controllers
中文描述： 三/五路電源控制器，提供跟蹤/排序功能
文件頁(yè)數(shù)： 21/30頁(yè)
文件大?。?/td> 475K
代理商： MAX1965
With the output pole
’
s frequency and series com-
pensation capacitor values, the required series
resistance can be determined. Based on the above
equation, select R
COMP
= 5.1M
.
Now we must determine if the selected output
capacitor
’
s ESR generates a second zero before
crossover
—
the circuit shown in Figure 1 uses a
1000μF 10V Sanyo CZ-series electrolytic capacitor
with an ESR rating of 0.2
, so the zero occurs at
800Hz. Since crossover occurs at 40kHz, add the
second parallel compensation capacitor.
Finally, the second compensation capacitor value
must be approximately 43pF. Select the closest
standard capacitor value of 47pF.
Boost-Supply Diode
A signal diode, such as the 1N4148, works well in most
applications. If the input voltage goes below 6V, use a
small 20mA Schottky diode for slightly improved effi-
ciency and dropout characteristics. Do not use large
power diodes, such as the 1N5817 or 1N4001, since
high junction capacitance can charge up VL to exces-
sive voltages.
Linear Regulator Controllers
Positive Output Voltage Selection
The MAX1964/MAX1965
’
s positive linear regulator out-
put voltages are set by connecting a voltage divider
from the output to FB_ to GND (Figure 6). Select R4 in
the 1k
to 50k
range. Calculate R3 with the following
equation:
where V
FB
= 1.24V and V
OUT
may range from 1.24V to
30V.
Negative Output Voltage Selection (MAX1965)
The MAX1965
’
s negative output voltage is set by con-
necting a voltage divider from the output to FB5 to a
positive voltage reference (Figure 6). Select R6 in the
1k
to 50k
range. Calculate R5 with the following
equation:
where V
REF
is the positive reference voltage used and
V
OUT
may be set between 0 and -20V.
If the negative regulator is used, the OUT pin must be
connected to a voltage supply between 2V and 5V that
can source at least 25mA. Typically, the OUT pin is
connected to the step-down converter
’
s output.
However, if the step-down converter
’
s output voltage is
set higher than 5V, OUT must be connected to one of
the positive linear regulators with an output voltage
between 2V and 5V.
Transistor Selection
The pass transistors must meet specifications for cur-
rent gain (h
FE
), input capacitance, collector-emitter sat-
uration voltage, and power dissipation. The transistor
’
s
current gain limits the guaranteed maximum output cur-
rent to:
where I
DRV
is the minimum 10mA base drive current
and R
BE
(220
) is the pullup resistor connected
between the transistor
’
s base and emitter. Furthermore,
the transistor
’
s current gain increases the linear regula-
tor
’
s DC loop gain (see
Stability Requirements
), so
excessive gain will destabilize the output. Therefore,
transistors with current gain over 100 at the maximum
output current, such as Darlington transistors, are not
recommended. The transistor
’
s input capacitance and
input resistance also create a second pole, which
could be low enough to destabilize the output when
heavily loaded.
The transistor
’
s saturation voltage at the maximum out-
put current determines the minimum input-to-output
voltage differential that the linear regulator will support.
Alternatively, the package
’
s power dissipation could
limit the useable maximum input-to-output voltage dif-
ferential. The maximum power dissipation capability of
the transistor
’
s package and mounting must exceed the
actual power dissipation in the device. The power dissi-
pated equals the maximum load current times the maxi-
mum input-to-output voltage differential:
P = I
LOAD(MAX)
(V
LDOIN -
V
OUT
) = I
LOAD(MAX)
V
CE
Stability Requirements
The MAX1964/MAX1965 linear regulators use an inter-
nal transconductance amplifier to drive an external
pass transistor. The transconductance amplifier, pass
transistor
’
s specifications, the base-emitter resistor,
and the output capacitor determine the loop stability. If
the output capacitor and pass transistor are not proper-
ly selected, the linear regulator will be unstable.
The transconductance amplifier regulates the output
voltage by controlling the pass transistor
’
s base cur-
rent. Since the output voltage is a function of the load
I
I
V
R
h
LOAD MAX
DRV
BE
BE
FE MIN
(
(
)
)
=
-
R
R
V
V
OUT
REF
5
6
=
R
R
V
V
OUT
FB
3
4
1
=
-
M
Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers
______________________________________________________________________________________
21
相關(guān)PDF資料
PDF描述
MAX1964TEEE Tracking/Sequencing Triple/Quintuple Power-Supply Controllers
MAX1965TEEP Tracking/Sequencing Triple/Quintuple Power-Supply Controllers
MAX1966 Low-Cost Voltage-Mode PWM Step-Down Controllers
MAX1967EUB Low-Cost Voltage-Mode PWM Step-Down Controllers
MAX1966-MAX1967 Low-Cost Voltage-Mode PWM Step-Down Controllers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1965TEEP 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel
MAX1965TEEP-T 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel
MAX1966ESA 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
MAX1966ESA+ 功能描述:電壓模式 PWM 控制器 Voltage-Mode PWM Step-Down RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
MAX1966ESA+T 功能描述:電壓模式 PWM 控制器 Voltage-Mode PWM Step-Down RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
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