- 您现在的位置：买卖IC网 > PDF目录1833 > LTC3876EFE#PBF (Linear Technology)IC CTLR DC/DC DDR DUAL 38-TSSOP PDF资料下载
参数资料
| 型号： | LTC3876EFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 21/48页 |
| 文件大小： | 0K |
| 描述： | IC CTLR DC/DC DDR DUAL 38-TSSOP |
| 产品培训模块： | LTC3876 Dual DC/DC Controller |
| 标准包装： | 50 |
| 应用： | 控制器，DDR，DDR2，DDR3 |
| 输入电压： | 4.5 V ~ 38 V |
| 输出数： | 2 |
| 输出电压： | 可调 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 38-TFSOP （0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 38-TSSOP 裸露焊盘 |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页当前第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页
LTC3876
APPLICATIONS INFORMATION
R SENSE RESISTOR
AND
PARASITIC INDUCTANCE
R ESL
V OUT
For today’s highest current density solutions the value
of the sense resistor can be less than 1mΩ and the
peak sense voltage can be as low as 20mV. In addition,
inductor ripple currents greater than 50% with operation
LTC3876
C F
F ≤ ESL/R S
up to 2MHz are becoming more common. Under these
SENSE +
SENSE –
C F
R F
R F
POLE-ZERO
CANCELLATION
3876 F03a
conditions, the voltage drop across the sense resistor’s
parasitic inductance becomes more relevant. A small RC
filter placed near the IC has been traditionally used to re-
duce the effects of capacitive and inductive noise coupled
FILTER COMPONENTS
PLACED NEAR SENSE PINS
Figure 3a. R SENSE Current Sensing
TO SENSE FILTER,
NEXT TO THE CONTROLLER
C OUT
in the sense traces on the PCB. A typical filter consists of
two series 10Ω resistors connected to a parallel 1000pF
capacitor, resulting in a time constant of 20ns.
This same RC filter, with minor modifications, can be
used to extract the resistive component of the current
sense signal in the presence of parasitic inductance.
For example, Figure 4a illustrates the voltage waveform
across a 2mΩ sense resistor with a 2010 footprint for a
R SENSE
3876 F03b
1.2V/15A converter operating at 100% load. The waveform
Figure 3b. Sense Lines Placement with Sense Resistor
R SENSE is chosen based on the required maximum output
current. Given the maximum current, I OUT(MAX) , maximum
sense voltage, V SENSE(MAX) , set by V RNG , and maximum
inductor ripple current ? I L(MAX) , the value of R SENSE can
be chosen as:
is the superposition of a purely resistive component and a
purely inductive component. It was measured using two
scope probes and waveform math to obtain a differential
measurement. Based on additional measurements of the
inductor ripple current and the on-time and off-time of
the top switch, the value of the parasitic inductance was
determined to be 0.5nH using the equation:
I OUT(MAX) –
V ESL(STEP) t ON ? t OFF
Δ I L
t ON + t OFF
R SENSE =
V SENSE(MAX)
Δ I L(MAX)
2
ESL = ?
where V ESL(STEP) is the voltage step caused by the ESL
Conversely, given R SENSE and I OUT(MAX) , V SENSE(MAX) and
thus V RNG voltage can be determined from the above equa-
tion. To ensure the maximum output current, sufficient
margin should be built in the calculations to account for
variations of LTC3876 under different operating conditions
and tolerances of external components.
Because of possible PCB noise in the current sensing
loop, the current sensing voltage ripple ? V SENSE = ? I L ?
R SENSE also needs to be checked in the design to get a
good signal-to-noise ratio. In general, for a reasonably
good PCB layout, 10mV of ? V SENSE is recommended as
a conservative number to start with, either for R SENSE or
inductor DCR sensing applications.
and shown in Figure 4a, and t ON and t OFF are top MOSFET
on-time and off-time respectively. If the RC time constant
is chosen to be close to the parasitic inductance divided by
the sense resistor (L/R), the resulting waveform looks re-
sistive again, as shown in Figure 4b. For applications using
low V SENSE(MAX) , check the sense resistor manufacturer’s
data sheet for information about parasitic inductance. In
the absence of data, measure the voltage drop directly
across the sense resistor to extract the magnitude of the
ESL step and use the equation above to determine the ESL.
However, do not over filter. Keep the RC time constant less
than or equal to the inductor time constant to maintain a
high enough ripple voltage on V RSENSE .
3876f
21
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3878EGN#PBF | IC REG CTRLR BUCK PWM CM 16-SSOP |
| LTC3879EUD#PBF | IC REG CTRLR BUCK PWM CM 16-QFN |
| LTC3880EUJ-1#PBF | IC REG CTRLR BUCK PWM CM 40-QFN |
| LTC3890EUH#PBF | IC REG CTRLR BUCK PWM CM 32-QFN |
| LTC3891EFE#PBF | IC REG CTRLR BUCK PWM CM 20TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3876EUHF#PBF | 功能描述:IC CTLR DC/DC DDR DUAL 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3876EUHF#TRPBF | 功能描述:IC CTLR DC/DC DDR DUAL 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3876IFE#PBF | 功能描述:IC CTLR DC/DC DDR DUAL 38-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3876IFE#TRPBF | 功能描述:IC CTLR DC/DC DDR DUAL 38-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3876IUHF#PBF | 功能描述:IC CTLR DC/DC DDR DUAL 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
发布紧急采购，3分钟左右您将得到回复。