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參數(shù)資料
| 型號： | MAX1994ETM |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual Step-Down Controllers Plus Linear- Regulator Controller for Notebook Computers |
| 中文描述： | DUAL SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, CQCC48 |
| 封裝： | 7 X 7 MM, 0.80 MM HEIGHT, THIN, QFN-48 |
| 文件頁數(shù)： | 35/49頁 |
| 文件大?。?/td> | 983K |
| 代理商： | MAX1994ETM |
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M
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
______________________________________________________________________________________
35
At the beginning of an output voltage transition, the regu-
lator is placed in forced-PWM mode and the PGOOD
output is high. If there is a fault on BUCK2 during this
period, PGOOD goes low. The output voltage follows the
internal DAC code, which changes in 25mV increments
until it reaches the programmed VID code. The regulator
remains in forced-PWM mode for 32 clock cycles after
the transition to ensure that the output settles properly.
The PGOOD output is forced high for 4 clock cycles after
the transition also to allow the output to settle. The slew-
rate clock frequency (set by the R
TIME
resistor) must be
set fast enough to ensure that the longest transition is
completed within the allotted time interval.
The output voltage transition is performed in 25mV steps,
preceded by a 4μs delay and followed by one additional
clock period. The total time for a transition depends on
R
TIME
, the voltage difference, and the accuracy of the
MAX1816/MAX1994s
’
slew-rate clock, and is not depen-
dent on the total output capacitance. The greater the out-
put capacitance, the higher the surge current required
for the transition. The MAX1816/MAX1994 automatically
control the current to the minimum level required to com-
plete the transition in the calculated time. As long as the
surge current is less than the current limit set by ILIM1,
the transition time is given by:
where f
SLEW
= 252kHz
×
143k
/ R
TIME
, V
OLD
is the
original DAC setting, and V
NEW
is the new DAC setting.
See Time Frequency Accuracy in the
Electrical
Characteristics
table for f
SLEW
accuracy. The practical
range of R
TIME
is 68k
to 680k
, corresponding to
1.9μs to 19μs per 25mV step. Although the DAC takes
discrete 25mV steps, the output filter makes the transi-
tions relatively smooth. The average inductor current
required to make an output voltage transition is:
I
L
C
OUT
25mV
f
SLEW
The slew-rate controller also performs a soft-start and
soft-stop function. The soft-start function works by
counting up from zero, in order to minimize turn-on
surge currents. The soft-stop executes this process in
reverse, eliminating the negative output voltages and
the need for an external Schottky output clamp diode
that would otherwise be required if DL1 were simply
forced high.
Setting BUCK2 Output Voltage
BUCK2
’
s Dual Mode
operation allows the selection of
common voltages without requiring external compo-
nents (Figure 1). In fixed mode, connect FB2 to AGND
for 2.5V output, or connect FB2 to V
CC
for 1.8V output.
In adjustable mode, the output voltage can be adjusted
from 1.0V to 5.5V using a resistive voltage-divider from
the BUCK2 output to AGND with the center tap con-
nected to FB2 (Figure 11). The equation for adjusting
the output voltage is:
where V
FB2
is 1.0V.
V
V
R
R
OUT
FB
2
2
1
1
2
=
+
t
s
f
V
V
mV
SLEW
SLEW
OLD
NEW
≤ μ +
4
+
1
1
25
Figure 9. Offset-Control Transfer Function
-0.15
-0.05
-0.10
0.05
0
0.10
0.15
UNDEFINED
0
1.0
0.5
OFS_ INPUT VOLTAGE (V)
0.8
1.2
1.5
2.0
O
Figure 10. Simplified Offset-Control Circuits
REF OR V
OUT1
REF OR V
OUT1
OR
OFS0
OFS1
OFS1
OFS0
OFS1
OFS2
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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PDF描述 |
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| MAX199AEWI | Fixed-Point Digital Signal Processor 532-FCBGA |
| MAX199AMYI | Circular Connector; No. of Contacts:18; Series:MS27505; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:15; Circular Contact Gender:Socket; Circular Shell Style:Box Mount Receptacle RoHS Compliant: No |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1994ETM+ | 功能描述:DC/DC 開關控制器 Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1994ETM+T | 功能描述:DC/DC 開關控制器 Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1994ETM-T | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1994EVKIT | 功能描述:DC/DC 開關控制器 Evaluation Kit for the MAX1816 MAX1980 MAX1994 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1995EGI | 功能描述:顯示驅動器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel |
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