- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377971 > ML4903 (Fairchild Semiconductor Corporation) High Current Synchronous Buck Controller For DC/DC conversion(用于DC/DC變換的大電流同步補(bǔ)償控制器（12V到1.8V～3.5V變換）) PDF資料下載
參數(shù)資料
| 型號(hào)： | ML4903 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | High Current Synchronous Buck Controller For DC/DC conversion(用于DC/DC變換的大電流同步補(bǔ)償控制器（12V到1.8V～3.5V變換）) |
| 中文描述： | 高電流同步降壓控制器，用于直流/直流轉(zhuǎn)換（用于直流/直流變換的大電流同步補(bǔ)償控制器（12V的到1.8?3.5V的變換）） |
| 文件頁數(shù)： | 10/12頁 |
| 文件大?。?/td> | 275K |
| 代理商： | ML4903 |
ML4903
10
DRV and P DRV switch the capacitive loads of the output
MOSFET gates. At the same time, GND must not see the
resulting switching spikes.
If a current sensing resistor is used, the voltage across the
resistor must be Kelvin-sensed. This ensures that the
ML4903 monitors only the voltage across the resistor, and
ignores the voltage drops and inductive transients in the
PCB traces which carry current into and out of this
resistor. The two pins of the ML4903 which must be
Kelvin-connected to the sense resistor are I
SENSE
and
GND. PWR GND should then return to the to the
grounded end of R
SENSE
as well, using a high current
Kelvin connection. This causes any noise across the
resistor to appear primarily as a common-mode signal on
I
SENSE
, GND, and PWR GND. Figure 4 shows a
recommended implementation of these PCB layout
requirements.
When directly monitoring the voltage across the channel
of the synchronous rectifier, the voltage across that
MOSFET should be sensed as closely as possible to its
drain. If a resistor divider is used to reduce the voltage at
the I
SENSE
pin for a given current through (Q3||Q4)’s
channel resistance, then the lower end of the divider
should be returned to the immediate vicinity of its source.
This ensures that the ML4903 monitors only the voltage
across the synchronous rectifier, and not the voltage drops
or inductive transients in the PCB traces which carry
current into and out of it. If a PC board with a dedicated
ground plane is used (recommended), the best return
points for GND and PGND are directly into the ground
plane. If the board does not have a dedicated ground
plane, GND must be returned to a point near the IC which
is relatively free from switching transients. Such a point
may need to be empirically determined but will usually
be near the ground connection of the output capacitor
bank.
MISCELLANEOUS POINTS
I
SENSE
is the input to a medium-speed, high-sensitivity
comparator (roughly comparable to an LM339-type
comparator in terms of speed of response). Because of the
leading-edge blanking on this comparator, it has a
substantial ability to reject switching noise. Still, proper
circuit function requires that the comparator not see
significant noise at the time during which the synchronous
rectifier MOSFET is on.
The compensation components R3 and C13 are high-
impedance nodes connected to the output of the voltage
loop error amplifier. These components should be kept in
close proximity to the ML4903. C13 should be returned to
GND, not to PWR GND or the ground plane of the PC
board.
Keep the V
REF
bypass capacitor C14 close to the ML4903.
Ensure that its ground connection is to GND, not to PWR
GND.
The 12V V
DD
input is both the converter's bulk power
input, and the supply from which the internal circuitry of
the ML4903 operates. V
DD
also provides the gate drive
for P DRV and N DRV. The V
DD
pin of the ML4903 should
be decoupled from the raw 12V system power to prevent
noise on the 12V supply from affecting the circuit's
switching action. A 10
W
resistor between 12V
IN
and V
DD
DESIGN CONSIDERATIONS
(Continued)
SENSE
RESISTOR
TO
ISENSE
TO
GND
TO
PWR GND
POWER GROUND RETURN
(GROUND PLANE)
TO
SYNCHRONOUS
RECTIFIER
MOSFET
SOURCE
Figure 4. Kelvin Sense Connections
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ML4950 | Adjustable Output, Low Current Single Cell Boost Regulator with Detect(帶低電檢測(cè)電路的輸出可調(diào)、低電流單節(jié)電池上電升壓穩(wěn)壓器) |
| ML4961 | Adjustable Output Low Voltage Boost Regulator with Detect(帶低電檢測(cè)電路的輸出可調(diào)、低電流單節(jié)電池上電升壓穩(wěn)壓器) |
| ML50000 | Echo Canceler(回聲消除器) |
| ML53612 | 64-Channel Full Duplex H.100/H.110 CT Bus System Interface and Time-Slot Interchange |
| ML60851D | USB Device Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4903CT | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML4950 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Adjustable Output, Low Current Single Cell Boost Regulator with Detect |
| ML4950 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML4950CS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ML4950ES | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Adjustable Output, Low Current Single Cell Boost Regulator with Detect |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。