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參數(shù)資料
| 型號(hào)： | MAX1717 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號(hào)處理 |
| 英文描述： | Replaced by TMS320VC5506 : Digital Signal Processors 132-BQFP |
| 中文描述： | 動(dòng)態(tài)可調(diào)、同步降壓型控制器，用于筆記本CPU |
| 文件頁數(shù)： | 28/32頁 |
| 文件大?。?/td> | 501K |
| 代理商： | MAX1717 |
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M
Dynamically Adjustable, Synchronous
Step-Down Controller for Notebook CPUs
28
______________________________________________________________________________________
The no-load output voltage is raised by adding a fixed
offset to GNDS through a resistor divider from REF. A
27mV nominal value is appropriate for 1.6V applications.
This 27mV corresponds to a 0.9
·
27mV = 24mV = 1.5%
increase with a V
OUT
of 1.6V. In the voltage-positioned
circuit (Figure 3), this is realized with resistors R4 and
R5. Use a 10μA resistor divider current.
Adding a series output resistor positions the full-load out-
put voltage below the actual DAC programmed voltage.
Connect FB and FBS directly to the inductor side of the
voltage-positioning resistor (R6, 5m
). The other side of
the voltage-positioning resistor should be tied directly to
the output filter capacitor with a short, wide PC board
trace. With a 14A full-load current, R6 causes a 70mV
drop. This 70mV is a -4.4% error, but it is compensated
by the +1.5% error from the GNDS offset, resulting in a
net error of -2.9%. This is well within the typical specifica-
tion for voltage accuracy.
An additional benefit of voltage positioning is reduced
power consumption at high load currents. Because the
output voltage is lower under load, the CPU draws less
current. The result is lower power dissipation in the
CPU, though some extra power is dissipated in R6. For
a nominal 1.6V, 12A output, reducing the output volt-
age 2.9% gives an output voltage of 1.55V and an out-
put current of 11.65A. Given these values, CPU power
consumption is reduced from 19.2W to 18.1W. The
additional power consumption of R6 is:
5m
·
11.65A
2
= 0.68W
and the overall power savings is as follows:
19.2 - (18.1 + 0.68) = 0.42W
In effect, 1W of CPU dissipation is saved and the power
supply dissipates much of the savings, but both the net
savings and the transfer of dissipation away from the
hot CPU are beneficial.
Effective efficiency is defined as the efficiency required
of a nonvoltage-positioned circuit to equal the total dis-
sipation of a voltage-positioned circuit for a given CPU
operating condition.
Calculate effective efficiency as follows:
1) Start with the efficiency data for the positioned circuit
(V
IN
, I
IN
, V
OUT
, I
OUT
).
2) Model the load resistance for each data point:
R
LOAD
= V
OUT
/ I
OUT
3) Calculate the output current that would exist for each
R
LOAD
data point in a nonpositioned application:
I
NP
= V
NP
/ R
LOAD
where V
NP
= 1.6V (in this example).
4) Calculate effective efficiency as:
Effective efficiency = (V
NP
·
I
NP
) / (V
IN
·
I
IN
) =
calculated nonpositioned power output divided by
the measured voltage-positioned power input.
5) Plot the efficiency data point at the nonpositioned
current, I
NP
.
The effective efficiency of voltage-positioned circuits is
shown in the
Typical Operating Characteristics
section.
Dropout Performance
The output voltage adjust range for continuous-conduc-
tion operation is restricted by the nonadjustable 500ns
(max) minimum off-time one-shot (375ns max at
1000kHz). For best dropout performance, use the slower
(200kHz) on-time settings. When working with low input
voltages, the duty-factor limit must be calculated using
worst-case values for on- and off-times. Manufacturing
tolerances and internal propagation delays introduce
an error to the TON K-factor. This error is greater at
higher frequencies (Table 3). Also, keep in mind that
transient response performance of buck regulators
operated close to dropout is poor, and bulk output
capacitance must often be added (see the VSAG equa-
tion in the
Design Procedure
section).
The absolute point of dropout is when the inductor cur-
rent ramps down during the minimum off-time (
I
DOWN
)
DL
DH
FB
FBS
GNDS
V
BATT
V
OUT
R1
1k
R2
180k
MAX1717
V
OUT
= V
FB
(
1 + R2 || 180k
)
R2
GND
Figure 11. Adjusting V
OUT
with a Resistor-Divider
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1717EEG | Replaced by TMS320VC5506 : Digital Signal Processors 100-LQFP |
| MAX1718EEI | Notebook CPU Step-Down Controller for Intel Mobile Voltage Positioning IMVP-II |
| MAX1718 | Replaced by TMS320VC5506 : Digital Signal Processors 100-LQFP -40 to 85 |
| MAX1718BEEI | Notebook CPU Step-Down Controller for Intel Mobile Voltage Positioning IMVP-II |
| MAX1720EUTG | Switched Capacitor Voltage Inverter with Shutdown |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX17175ETG+ | 制造商:Maxim Integrated Products 功能描述:BOOST REG W/INTEGRATED CHARGE PUMPS SWITCH CONTROL & HIGH-CU - Rail/Tube |
| MAX1717BEEG | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
| MAX1717BEEG+ | 功能描述:DC/DC 開關(guān)控制器 Adj Synchronous Step-Down RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
| MAX1717BEEG+T | 功能描述:DC/DC 開關(guān)控制器 Adj Synchronous Step-Down RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
| MAX1717BEEG-T | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
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