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參數(shù)資料
| 型號： | MAX1717 |
| 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 132-BQFP |
| 中文描述： | 動態(tài)可調(diào)、同步降壓型控制器，用于筆記本CPU |
| 文件頁數(shù)： | 24/32頁 |
| 文件大小： | 501K |
| 代理商： | MAX1717 |
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M
Dynamically Adjustable, Synchronous
Step-Down Controller for Notebook CPUs
24
______________________________________________________________________________________
been set. The PWM operates as if SKP/
SDN
were high
(SKIP mode). The NO FAULT test mode is entered by
forcing 12V to 15V on SKP/
SDN
.
Design Procedure
Firmly establish the input voltage range and maximum
load current before choosing a switching frequency
and inductor operating point (ripple-current ratio). The
primary design trade-off lies in choosing a good switch-
ing frequency and inductor operating point, and the fol-
lowing four factors dictate the rest of the design:
1)
Input Voltage Range.
The maximum value (V
IN(MAX)
)
must accommodate the worst-case high AC adapter
voltage. The minimum value (V
IN(MIN)
) must account
for the lowest battery voltage after drops due to con-
nectors, fuses, and battery selector switches. If there
is a choice at all, lower input voltages result in better
efficiency.
2)
Maximum Load Current.
There are two values to con-
sider. The
peak load current
(I
LOAD(MAX)
) deter-
mines the instantaneous component stresses and
filtering requirements, and thus drives output capaci-
tor selection, inductor saturation rating, and the
design of the current-limit circuit. The
continuous load
current
(I
LOAD
) determines the thermal stresses and
thus drives the selection of input capacitors,
MOSFETs, and other critical heat-contributing com-
ponents. Modern notebook CPUs generally exhibit
I
LOAD
= I
LOAD(MAX)
·
80%.
3)
Switching Frequency.
This choice determines the
basic trade-off between size and efficiency. The opti-
mal frequency is largely a function of maximum input
voltage, due to MOSFET switching losses that are pro-
portional to frequency and V
IN2
. The optimum frequen-
cy is also a moving target, due to rapid improvements
in MOSFET technology that are making higher frequen-
cies more practical.
4)
Inductor Operating Point.
This choice provides trade-
offs between size vs. efficiency. Low inductor values
cause large ripple currents, resulting in the smallest
size, but poor efficiency and high output noise. The
minimum practical inductor value is one that causes
the circuit to operate at the edge of critical conduction
(where the inductor current just touches zero with
every cycle at maximum load). Inductor values lower
than this grant no further size-reduction benefit.
The MAX1717’s pulse-skipping algorithm initiates
skip mode at the critical conduction point. So, the
inductor operating point also determines the load-
current value at which PFM/PWM switchover occurs.
The optimum point is usually found between 20%
and 50% ripple current.
5) The inductor ripple current also impacts transient-
response performance, especially at low V
IN
- V
OUT
differentials. Low inductor values allow the inductor
current to slew faster, replenishing charge removed
from the output filter capacitors by a sudden load
step. The amount of output sag is also a function of
the maximum duty factor, which can be calculated
from the on-time and minimum off-time:
SKP/
SDN
DL
MODE
COMMENT
GND
High
Shutdown
Low-power shutdown state. DL is forced to V
DD
, enforcing
OVP. I
CC
+ I
DD
= 2μA typ.
12V to 15V
Switching
No Fault
Test mode with faults disabled and fault latches cleared, includ-
ing thermal shutdown. Otherwise, normal operation, with auto-
matic PWM/PFM switchover for pulse-skipping at light loads.
Float
Switching
Run (PWM, low noise)
Low-noise operation with no automatic switchover. Fixed-fre-
quency PWM action is forced regardless of load. Inductor cur-
rent reverses at light load levels.
V
CC
Switching
Run (PFM/PWM,
normal operation)
Normal operation with automatic PWM/PFM switchover for
pulse-skipping at light loads.
V
CC
or Float
High
Fault
Fault latch has been set by OVP, UVP, or thermal shutdown.
Device will remain in FAULT mode until V
CC
power is cycled or
SKP/
SDN
is forced low.
Table 5. Operating Mode Truth Table
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|---|---|
| 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 |
相關代理商/技術參數(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 |
| MAX1717BEEG+ | 功能描述:DC/DC 開關控制器 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 |
| MAX1717BEEG+T | 功能描述:DC/DC 開關控制器 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 |
| MAX1717BEEG-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 |
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