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參數(shù)資料
| 型號： | MAX1813 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號處理 |
| 英文描述： | Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP |
| 中文描述： | 動態(tài)可調(diào)、同步降壓型控制器，集成電壓定位電路 |
| 文件頁數(shù)： | 28/38頁 |
| 文件大小： | 738K |
| 代理商： | MAX1813 |
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M
Dynamically-Adjustable, Synchronous Step-Down
Controller with Integrated Voltage Positioning
28
______________________________________________________________________________________
where D = V
OUT
/V
IN
is the regulator
’
s duty cycle.
However, since the ratio of the output-to-input voltage
is usually relatively large, the effect of the duty cycle on
the circuit
’
s performance is not significant. Therefore,
the complete expression for the voltage-positioned out-
put depends upon the load current, the value of the
voltage-positioning gain resistor, and the value of the
current-sense resistor:
The MAX1813 voltage-positioning circuit has several
advantages over older circuits, which added a fixed
voltage offset on the sense point and used a low-value
resistor in series with the output. The new circuit uses
the same current-sense resistor for both voltage posi-
tioning and current-limit detection. This simultaneously
provides accurate current limiting and voltage position-
ing. Since the new circuit adjusts the output voltage
within the control loop, the voltage-positioning signal
may be internally amplified. The additional gain allows
the use of low-value current-sense resistors, so the
power dissipated in this sense resistor is significantly
lower than a single resistor connected directly in series
with the output.
The current-sense signal from the sense resistor to the
VPCS pin should be filtered to eliminate the effect of
switching noise on the voltage-positioned output. A
simple low-pass RC filter with a 100ns time constant
(100
x 1000pF) sufficiently reduces the noise on the
current-sense signal (Figure 8).
Voltage-Positioning Compensation (CC)
The voltage-positioning compensation capacitor filters
the amplified VPCS signal, allowing the user to adjust
the dynamics of the voltage-positioning loop. Since the
output impedance of the transconductance amplifier is
much greater than R
AVPS
, the pole provided by this
node can be approximated by 1/(2
π
R
AVPS
C
COMP
). The
response time is set with a 47pF to 1000pF capacitor
from CC to GND.
Applications Information
Voltage Positioning and Effective
Efficiency
Powering new mobile processors requires careful
attention to detail to reduce cost, size, and power dissi-
pation. As CPUs became more power hungry, it was
recognized that even the fastest DC-DC converters
were inadequate to handle the transient power require-
ments. After a load transient, the output instantly
changes by ESR
COUT
x
I
LOAD
. Conventional DC-DC
converters respond by regulating the output voltage
back to its nominal state after the load transient occurs
(Figure 9). However, the CPU only requires that the out-
put voltage remains above a specified minimum value.
Dynamically positioning the output voltage to this lower
limit allows the use of fewer output capacitors and
reduces power consumption under load.
For a conventional (nonvoltage-positioned) circuit, the
total voltage change is:
V
V
1-
G R
REF
R
V
I
OUT
OUT(PROG)
≈
MAX1813
Q
2
DL
VPCS
CC
REF
PGND
GND
R
SENSE
R
VPCS
C
VPCS
C
REF
R
AVPS
C
COMP
Figure 8. Voltage-Positioning Block Diagram
B
1.4V
1.4V
A
A. CONVENTIONAL CONVERTER (50mV/div)
B. VOLTAGE-POSITIONED OUTPUT (50mV/div)
VOLTAGE POSITIONING THE OUTPUT
Figure 9. Voltage Positioning the Output
相關PDF資料 |
PDF描述 |
|---|---|
| MAX182AEWI | Calivrated 4-Channel 12-Bit ADC with T/H and Refernce |
| MAX182AEPI | Calivrated 4-Channel 12-Bit ADC with T/H and Refernce |
| MAX182BEPI | Calivrated 4-Channel 12-Bit ADC with T/H and Refernce |
| MAX182ACPI | Replaced by TMS320BC52 : Digital Signal Processors 100-LQFP -40 to 85 |
| MAX182ACWI | Replaced by TMS320BC52 : |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1813EEI | 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 |
| MAX1813EEI+ | 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 |
| MAX1813EEI+T | 功能描述:DC/DC 開關控制器 Dynamically Adjustable Synchronous Step-Down Controller w/Integrated Voltage Positioning 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 |
| MAX1813EEI-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 |
| MAX1813EVKIT | 功能描述:DC/DC 開關控制器 Evaluation Kit for the MAX1813 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 |
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