參數(shù)資料
型號(hào)： MAX783SCBX
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： Triple-Output Power-Supply Controller for Notebook Computers
中文描述： DUAL SWITCHING CONTROLLER, 330 kHz SWITCHING FREQ-MAX, PDSO36
封裝： PLASTIC, SSOP-36
文件頁(yè)數(shù)： 17/28頁(yè)
文件大?。?/td> 279K
代理商： MAX783SCBX
Diode D3
The voltage rating of D3 should be at least 4 x V
+
5V plus a safety margin. A rating of at least 100V is
necessary for the maximum 20V supply. Use a high-
speed silicon diode (with a higher breakdown voltage
and low capacitance) rather than a Schottky diode.
D3’s current rating should exceed twice the maximum
current load on VDD.
Diodes D2 and D5
Use 1N5819s or similar Schottky diodes. D2 and D5
conduct only about 3% of the time, so the 1N5819’s 1A
current rating is conservative. The voltage rating of D2
and D5 must exceed the maximum input supply volt-
age from the battery. These diodes must be Schottky
diodes to prevent the lossy MOSFET body diodes from
turning on, and they must be placed physically close to
their associated synchronous rectifier MOSFETs.
S oft-S tart Capac itors (C13, C14)
A capacitor connected from GND to either SS pin caus-
es that supply to ramp up slowly. The ramp time to full
current limit, t
, is approximately 1ms for every nF of
capacitance on SS_, with a minimum value of 10μs.
Typical capacitor values are in the 10nF to 100nF range.
Because this ramp is applied to the current-limit circuit,
the actual time for the output voltage to ramp up
depends on the load current and output capacitor
value. Using Figure 1’s circuit with a 2A load and no
SS capacitor, full output voltage is reached in less than
1ms after ON_ is driven high.
Bypass Capac itors
Input Filter Capacitors (C1, C2)
Use at least 3μF/W of output power for the input filter
capacitors, C1 and C2. They should have less than
150m
ESR, and should be located no further than
10mm from N1 and N2 to prevent ringing. Connect the
negative terminals directly to PGND. Be careful not to
exceed the surge current ratings of the bypass capaci-
tors. If the battery pack or AC adapter has very low
output impedance, tantalum capacitors may be dam-
aged when initial connection is made. In this situation,
electrolytic capacitors such as Sanyo OS-CON may be
necessary. Also, take care that the RMS input current
of the MAX783 circuit does not exceed the bypass
capacitor ripple current rating. The RMS input current
(I
RMS
) can be calculated as shown below:
I
RMS
= RMS AC input current
————————
√
V
(V
- V
)
= I
LOAD
———————–——
V
IN
Low-V oltage Operation
Low input voltages, such as the 6V end-of-life voltage
of a 6-cell NiCd battery, place extra demands on the
+5V buck regulator because of the very low input-out-
put differential voltage. The standard application cir-
cuit works well with supply voltages down to 6V; at
input voltages less than 6V, the +5V filter capacitor
values must be increased. If the minimum battery
voltage is 6.5V or higher, the 660μF total 5V filter
capacitance can be reduced to 330μF.
The + 5V supply’s load-transient response is
impaired due to reduced inductor-current slew rate,
which is in turn caused by reduced voltage applied
across the buck inductor during the high-side
switch-on time. So, the +5V output sags when hit
with an abrupt load current change, unless the +5V
filter capacitor value is increased. Only the capaci-
tance is affected and ESR requirements don’t
change. Therefore, the added capacitance can be
supplied by an additional low-cost bulk capacitor in
parallel with the normal low-ESR switching-regulator
capacitor. The equation for voltage sag under a
step-load change follows:
(I
STEP2
)(L)
V
SAG
= —————————————————
(2)(C
F
) (V
IN(MIN)
x DMAX - V
OUT
)
where DMAX is the maximum duty cycle. Higher duty
cycles are possible when the oscillator frequency is
reduced to 200kHz, due to fixed propagation delays
through the PWM comparator becoming a lesser part of
the whole period. The tested worst-case limit for DMAX
is 92% at 200kHz. Lower inductance values can reduce
the filter capacitance requirement, but only at the
expense of increased noise at high input voltages
(resulting from higher peak currents).
M
Triple-Output Power-S upply Controller
for Notebook Computers
______________________________________________________________________________________
17
)
相關(guān)PDF資料
PDF描述
MAX790CPA Analog IC
MAX793RCPE Power Supply Supervisor
MAX793RCSE Power Supply Supervisor
MAX793REPE Power Supply Supervisor
MAX793RESE Power Supply Supervisor
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX783SCBX-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
MAX783SEBX 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
MAX783SEBX-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
MAX785CAI 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX785CAI-T 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*