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| 型号： | XRP6142EVB |
| 厂商： | Exar Corporation |
| 文件页数： | 11/17页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR XRP6142 |
| 特色产品： | XRP6142 Synchronous Step-Down Controllers |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 2.5V |
| 电流 - 输出： | 15A |
| 输入电压： | 3.3 ~ 5.5 V |
| 稳压器拓扑结构： | 降压 |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | XRP6142 |
| 相关产品： | 1016-1333-ND - IC CTRLR STEP-DWN SYNC 16QFN 1016-1332-ND - IC CTRLR STEP-DWN SYNC 16QFN 1016-1331-ND - IC CTRLR STEP-DWN SYNC 16QFN |
| 其它名称： | 1016-1334 |
X R P 6 1 4 2
S y n c h r o n o u s S t e p - D o w n C o n t r o l l e r w i t h D D R
M e m o r y T e r m i n a t i o n
I OUT , MAX × V OUT × ( V IN ? V OUT )
R DS ( ON ) ≤
t r + t f =
2 × V OUT
R DS ( ON ) ≤
D × I OUT
C IN = 2
fs × 0 . 02 V IN × V IN
S YNCHRONOUS FET (L OW - SIDE FET)
Select the synchronous FET for voltage rating
BV DSS , on resistance rating R DS(ON) and gate
drive rating V GS . As a rule of thumb, voltage
rating should be at least twice the converter
input voltage. FETs with voltage rating of up to
30V should provide satisfactory performance.
Drive voltage of 4.5V is sufficient for
applications with minimum input voltage of
4.5V. For applications with a lower input
voltage a FET with 2.5V gate drive should be
selected. Switching losses of the Synchronous
FET are negligible in comparison to its
conduction losses. R DS(ON) is calculated based
on conduction losses from:
P Conduction
( 1 ? D ) × I OUT 2
It is common practice to allocate 50% of the
total FET losses to the synchronous FET. As an
example, consider a 10W buck converter with
a target efficiency of 90%. Therefore, the
target total power loss is 1.1W. Assume that
the only significant non-FET loss is the
inductor loss estimated at 0.1W. Thus the
maximum conduction loss of the synchronous
FET should not exceed 0.5W. By using this
value in the above equation R DS(ON) can be
calculated and a suitable FET selected.
S WITCHING FET (H IGH - SIDE FET)
Select the switching FET for voltage rating
BV DSS , on-resistance rating R DS(ON) , gate drive
rating V GS , rise time t r and fall time t f . BV DSS
and V GS selection guidelines are the same as
Synchronous FET. The switching FET incurs
switching (i.e., transitional) as well as
conduction losses. R DS(ON) is calculated based
on conduction losses from:
P Conduction
2
It is common practice to allocate 50% of the
total high-side FET losses to conduction.
Proceeding with the example from previous
section the total target loss is 0.5W, and thus
target conduction loss equals 0.25W. By using
this value in the above equation R DS(ON) can be
calculated. Rise and fall time can be
approximated from:
P Switching
V IN × I out × f s
Since the allotted switching loss budget is
0.25W, t r and t f can be calculated from the
above equation.
For a detailed explanation of FET losses and
FET selection procedure refer to EXAR
application note ANP-20.
R-C S NUBBER (O PTIONAL )
An R-C snubber placed across the synchronous
FET eliminates the ringing and reduces the
amplitude of overshoot at SW node. Use
surface-mount components and place them
close to the FET drain-source. Calculate the
value of snubber capacitor Csnb from:
Csnb = 3 × Coss
Coss is the output capacitance of the
synchronous FET corresponding to V IN .
Calculate the value of the snubber resistor
Rsnb from:
Rsnb =
I OUT
DDR MEMORY POWER APPLICATIONS
XRP6142 can be used to generate the required
V DDQ (V DD ) or V TT Reference voltages for DDR I,
II and III memories and provides a 40mA
buffered V TT Reference voltage. When used in
conjunction with Exar’s SP2996 DDR Memory
Termination, the XRP6142 provides a complete
DDR power management solution. A cost-
effective DDR2 solution is shown on page 15.
XRP6142 provides the VDDQ and VTTREF
voltages. SP2996 provides the VTT voltage.
Please note that the current output of VDDQ
can be increased up to 10A by using a larger
QT/QB MOSFET and scaling the L1 and C3
accordingly.
? 2010 Exar Corporation
Page 11 of 17
Rev. 1.0.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| XRP6153EL-F | 功能描述:开关变换器、稳压器与控制器 Synchronization RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| XRP6153EVB | 功能描述:数据转换 IC 开发工具 300kHz Sync Bck Cont w/Frequency Sync RoHS:否 制造商:Texas Instruments 产品:Demonstration Kits 类型:ADC 工具用于评估:ADS130E08 接口类型:SPI 工作电源电压:- 6 V to + 6 V |
| XRP6272IDBTR-F | 功能描述:低压差稳压器 - LDO 2A LDO LOW NOISE 5V AND ADJ OUTPUT RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| XRP6272ITC5TR-F | 功能描述:低压差稳压器 - LDO 2A LDO LOW NOISE 5V AND ADJ OUTPUT RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| XRP6274EH-F | 制造商:Exar Corporation 功能描述:Single Supply LDOs With 140mV Dropout |
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