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參數(shù)資料
| 型號： | MAX5003 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | High-Voltage PWM Power-Supply Controller |
| 中文描述： | 高壓PWM電源控制器 |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 170K |
| 代理商： | MAX5003 |
M
where:
R
MAXTON
= Resistor between the MAXTON pin and
ground
V
MIN
= Minimum power-line voltage
V
UVL
= Power-line trip voltage
DC
MAX
(V
MIN
) = Maximum duty cycle at minimum
power-line voltage
For this application circuit, a 10% margin is reason-
able, so the value used is 50k
. This gives a maxi-
mum duty cycle of 50%. The maximum duty cycle
can now be expressed as:
where:
V
CON
= Voltage at the CON pin, input of the PWM
comparator
DC(V
CON
, V
IN
) = Duty cycle, function of V
CON
and
V
IN
0.5V and 2.5V are the values at the beginning and
end of the PWM ramp.
The term
SW
/
NOM
varies from 0.8 to 1.2 to allow
for clock frequency variation. If the clock is running
at 300kHz and the input voltage is fixed, then the
duty cycle is a scaled portion of the maximum duty
cycle, determined by V
CON
.
7) Low-ESR/ESL ceramic capacitors were used in this
application. The output filter is made by two 22μF
ceramic capacitors in parallel. Normally, the ESR of
a capacitor is a dominant factor determining the rip-
ple, but in this case it is the capacitor value.
Calculating
the ripple will be a fraction of this depending on the
duty cycle. For a 50% duty cycle, the ripple due to
the capacitance is approximately 45mV.
8)The PWM gain can be calculated from:
Note that while the above formula incorporates the
product of the maximum duty cycle and V
IN
, it is
independent of V
IN
. For 1A output (R
L
= 5
), the
PWM gain is +3.0V/V. For a 10% load (R
L
= 50
),
the gain is multiplied by the square root of 10 and
becomes +10V/V. The pole of the system due to the
output filter is 1 / 2
π
RC, where R is the load resis-
tance and C the filter capacitor. Choosing a capaci-
tor and calculating the pole frequency by:
it is 723Hz at full load. At 10% load it will be 72Hz,
since the load resistor is then 50
instead of 5
. The
total loop gain is equal to the PWM gain times the
gain in the combination of the voltage divider and
the error amplifier. The worst case for phase margin
is at full load. For a phase margin of 60 degrees, this
midband gain (G) must be set to be less than:
where:
U
= Unity-gain frequency of error amplifier
PM = Phase margin angle
The DC accuracy of the regulator is a function of the
DC gain. For 1% accuracy, a DC gain of 20 is required.
Since the maximum midband gain for a stable
response is 16, an integrator with a flat midband gain
given by a zero is used. The midband gain is less than
16, to preserve stability, and the DC gain is much larger
than 20, to achieve high DC accuracy.
Optimization on the bench showed that a midband gain
of 5 gave fast transient response and settling with no
ringing. The zero was pushed as high in frequency as
possible without losing stability. The zero must be a
factor of two or so below the system unity-gain frequen-
cy (crossover frequency) at minimum load. With the
G
PM A
)
MHz
Hz
UErrorAmp
PWM
P
tan(
.
<
=
1
1 7 3 723
=
=
L
L
R
C
F
1
2
1
2
5
44
π
π
μ
A
dV
dV
=
R
2 L
V
2.0V
R
2 L
PWM
OUT
CON
L
PRI
SW
MIN
L
PRI
SW
=
=
.
%
(
)
DC
V
V
MAX VMIN
36
2 0
50
3
I
C
A
kHz
F
mV
OUT
SW
=
=
1
300
44
76
μ
DC(V
) =
V
0.5V
2.0V
2.0V
50%
DC(V
)
V
0.5V
25%
DC(2.5V,V
DC(2.5V,V
DC(0.5V,V
DC(0.5V,V
)
50%
25%
0
0
=
)
)
)
CON MIN
CON
CON MAX
CON
MIN
MAX
MIN
MAX
=
=
=
=
DC(V
)
V
0.5V
2.0V
V
V
DC
V
- 0.5V
2.0V
36V
V
IN
50%
CON,VIN
CON
MIN
IN
NOM
MAX(VMIN)
CON
SW
NOM
=
≈
SW
High-Voltage PWM
Power-Supply Controller
14
______________________________________________________________________________________
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| MAX5003CEE | High-Voltage PWM Power-Supply Controller |
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相關(guān)代理商/技術(shù)參數(shù) |
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| MAX5003-50WEVKIT | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Evaluation Kit for the MAX5003-50W |
| MAX5003C/D | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:High-Voltage PWM Power-Supply Controller |
| MAX5003CEE | 功能描述:電壓模式 PWM 控制器 PWM Power-Supply Controller 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 |
| MAX5003CEE+ | 功能描述:電壓模式 PWM 控制器 PWM Power-Supply Controller 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 |
| MAX5003CEE+T | 功能描述:電壓模式 PWM 控制器 PWM Power-Supply Controller 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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