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参数资料
| 型号： | IRDC3822 |
| 厂商： | International Rectifier |
| 文件页数： | 16/21页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL SYNC BUCK CONVERTER |
| 产品变化通告： | (EP) Parts Discontinuation 25/May/2012 |
| 标准包装： | 1 |
| 系列： | * |
PD-60333
IR3822MPBF
The R DS(on)
Programming the Current-Limit
The Current-Limit threshold can be set by
connecting a resistor (R SET ) from drain of the
low-side MOSFET to the OCSet pin. The
resistor can be calculated by using equation (3).
has a positive temperature
coefficient and it should be considered for the
worse case operation. This resistor must be
placed close to the IC, place a small ceramic
capacitor from this pin to power ground (PGnd)
for noise rejection purposes.
Layout Consideration
The layout is very important when designing high
frequency switching converters. Layout will affect
noise pickup and can cause a good design to
perform with less than expected results.
Start to place the power components, making all
the connection in the top layer with wide, copper
filled areas.
The inductor, output capacitor and the IR3822
should be as close to each other as possible.
This helps to reduce the EMI radiated by the
I SET = I L(critical ) =
R OCSet ? I OCSet
R DS(on)
- -(3)
power traces due to the high switching currents
through them. Place the input capacitor directly to
the Vin pin of IR3822. To reduce the ESR replace
the single input capacitor with two parallel units.
The feedback part of the system should be kept
I SET = (I o ? 1 . 5 ) +
Δ i = ( V in - V o ) ?
R DS(on) = 18m ? ? υ = 18m ? ? 1 .5 = 27m ?
where :
υ : Temperatur e Dependency
Note : Use 24 m ? for low - side MOSFET
if 5V is used for V cc
Δ i
2
where :
I o : Max Output Current
Δ i : Inductor ripple current
V o
V in ? L ? F s
I SET = (4A ? 1.5) + 0 . 85 A = 6.85A
R OCSet = R 7 = 9.31K ?
Setting the Power Good Threshold
Power Good threshold can be programmed by
using two external resistors (see figure 16).
The following formula can be used to set the
threshold:
away from the inductor and other noise sources.
The critical bypass components such as
capacitors for Vcc and Vc should be close to their
respective pins. It is important to place the
feedback components including feedback
resistors and compensation components close to
Fb and Comp pins.
In a multilayer PCB use one layer as a power
ground plane and have a control circuit ground
(analog ground), to which all signals are
referenced. The goal is to localize the high
current path to a separate loop that does not
interfere with the more sensitive analog control
function. These two grounds must be connected
together on the PC board layout at a single point.
The Power QFN is a thermally enhanced
package. Based on thermal performance it is
recommended to use at least a 4-layers PCB. To
effectively remove heat from the device the
exposed pad should be connected to the ground
plane using vias.
R 2 =
0 . 38 V
0 . 9 *V out - 0 . 38 V
*R 1
--( 19 )
Where:
0.38V is reference of the internal comparator
0.9*Vout is selectable threshold for power good,
for this design it is 1.62V.
Select R 1 =10KOhm
Using (18): R 2 =3.06KOhm
Select R 2 =3.09K
Use a pull up resistor (4.99K) from PGood pin to
Vcc.
11/04/08
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| IRDC3822A | 功能描述:电源管理IC开发工具 IR3822A SYNC CONV 300kHz EVAL BRD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3823 | 制造商:International Rectifier 功能描述:IRDC3823 Eval Board for IR3823 SupIRBuck Single-Input Voltage, Synchronous Buck 制造商:International Rectifier 功能描述:Power Management IC Development Tools Demokit IR3823M Dev Board |
| IRDC3831 | 功能描述:电源管理IC开发工具 IR3831 SYNC CONV 600kHz EVAL BRD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3831W | 功能描述:电源管理IC开发工具 User Guide IR3831W Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3832W | 功能描述:电源管理IC开发工具 User Guide IR3832W Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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