參數(shù)資料
型號(hào)： MAX1717EEG
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： Replaced by TMS320VC5506 : Digital Signal Processors 100-LQFP
中文描述： SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO24
封裝： 0.150 INCH, 0.025 INCH PITCH, MO-137AC, QSOP-24
文件頁(yè)數(shù)： 14/32頁(yè)
文件大?。?/td> 501K
代理商： MAX1717EEG
M
Dynamically Adjustable, Synchronous
Step-Down Controller for Notebook CPUs
14
______________________________________________________________________________________
Detailed Description
+5V Bias Supply (V
CC
and V
DD
)
The MAX1717 requires an external +5V bias supply in
addition to the battery. Typically, this +5V bias supply
is the notebook’s 95% efficient +5V system supply.
Keeping the bias supply external to the IC improves
efficiency and eliminates the cost associated with the
+5V linear regulator that would otherwise be needed to
supply the PWM circuit and gate drivers. If stand-alone
capability is needed, the +5V supply can be generated
with an external linear regulator.
The +5V bias supply must provide V
CC
(PWM con-
troller) and V
DD
(gate-drive power), so the maximum
current drawn is:
I
BIAS
= I
CC
+ f (Q
G1
+ Q
G2
) = 10mA to 40mA (typ)
where I
CC
is 700μA (typ), f is the switching frequency,
and Q
G1
and Q
G2
are the MOSFET data sheet total
gate-charge specification limits at V
GS
= 5V.
V+ and V
DD
can be tied together if the input power
source is a fixed +4.5V to +5.5V supply. If the +5V bias
supply is powered up prior to the battery supply, the
enable signal (SKP/
SDN
going from low to high or
open) must be delayed until the battery voltage is pre-
sent to ensure startup.
Free-Running, Constant On-Time PWM
Controller with Input Feed-Forward
The Quick-PWM control architecture is a pseudofixed-
frequency, constant-on-time current-mode type with
voltage feed-forward (Figure 2). This architecture relies
on the output filter capacitor’s ESR to act as the current-
sense resistor, so the output ripple voltage provides the
PWM ramp signal. The control algorithm is simple: the
high-side switch on-time is determined solely by a one-
shot whose period is inversely proportional to input volt-
age and directly proportional to output voltage. Another
one-shot sets a minimum off-time (400ns typ). The on-
time one-shot is triggered if the error comparator is low,
the low-side switch current is below the current-limit
threshold, and the minimum off-time one-shot has timed
out.
On-Time One-Shot (TON)
The heart of the PWM core is the one-shot that sets the
high-side switch on-time. This fast, low-jitter, adjustable
one-shot includes circuitry that varies the on-time in
response to battery and output voltage. The high-side
switch on-time is inversely proportional to the battery
voltage as measured by the V+ input, and proportional
to the output voltage. This algorithm results in a nearly
constant switching frequency despite the lack of a
fixed-frequency clock generator. The benefits of a con-
stant switching frequency are twofold: first, the frequency
can be selected to avoid noise-sensitive regions such
as the 455kHz IF band; second, the inductor ripple-cur-
rent operating point remains relatively constant, resulting
in easy design methodology and predictable output
voltage ripple.
On-Time = K (V
OUT
+ 0.075V) / V
IN
where K is set by the TON pin-strap connection and
0.075V is an approximation to accommodate the expect-
ed drop across the low-side MOSFET switch (Table 3).
The on-time one-shot has good accuracy at the operating
points specified in the
Electrical Characteristics table
(±10% at 200kHz and 300kHz, ±12% at 550kHz and
1000kHz). On-times at operating points far removed from
the conditions specified in the
Electrical Characteristics
table can vary over a wide range. For example, the
1000kHz setting will typically run about 10% slower with
inputs much greater than +5V due to the very short on-
times required.
On-times translate only roughly to switching frequencies.
The on-times guaranteed in the
Electrical Character-
istics
table are influenced by switching delays in the
Table 2. Component Suppliers
Table 3. Approximate K-Factors Errors
±10
TON
SETTING
(kHz)
APPROXIMATE
K-FACTOR
ERROR (%)
MIN RECOMMENDED
V
BATT
AT V
OUT
= 1.6V
(V)
200
±10
2.1
300
2.3
550
±12.5
3.2
1000
±12.5
4.5
K
FACTOR
(μs)
5
3.3
1.8
1.0
MANUFACTURER
USA PHONE
FACTORY FAX
[Country Code]
[1] 847-639-1469
[1] 402-563-6418
[1] 310-322-3332
[1] 408-986-1442
[1] 714-373-7183
[81] 3-3607-5144
[1] 408-573-4159
Coilcraft
Dale-Vishay
International Rectifier
Kemet
Panasonic
Sumida
Taiyo Yuden
847-639-6400
402-564-3131
310-322-3331
408-986-0424
714-373-7939
847-956-0666
408-573-4150
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1717EEG+ 功能描述:DC/DC 開(kāi)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(kāi)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
MAX1717EEG+C71058 功能描述:DC/DC 開(kāi)關(guān)控制器 Step-Down Controller for Notebook CPU RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1717EEG+T 功能描述:DC/DC 開(kāi)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(kāi)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
MAX1717EEG-C71058 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1717EEG-T 功能描述:DC/DC 開(kāi)關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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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