参数资料
型号: LTC3867EUF#PBF
厂商: Linear Technology
文件页数: 15/36页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM CM 24-QFN
产品培训模块: LTC3867 Synchronous Step-Down DC/DC Controller
标准包装: 91
PWM 型: 电流模式
输出数: 1
频率 - 最大: 1.2MHz
占空比: 98%
电源电压: 4 V ~ 38 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 125°C
封装/外壳: 24-WFQFN 裸露焊盘
包装: 管件
LTC3867
APPLICATIONS INFORMATION
V IN
INTV CC
BOOST
TG
V IN
SENSE RESISTOR
PLUS PARASITIC
INDUCTANCE
LTC3867
SW
R S
ESL
V OUT
BG
PGND
SENSE +
SENSE –
SGND
C F
R F
R F
C F ? 2 ? R F ≤ ESL/R S
POLE-ZERO
CANCELLATION
FILTER COMPONENTS
PLACED NEAR SENSE PINS
(3a) Using a Resistor to Sense Current
V IN
INTV CC
3867 F03a
V IN
OPTIONAL
TEMP COMP
NETWORK
BOOST
TG
SW
LTC3867
INDUCTOR
L DCR
V OUT
R S
ITEMP
BG
PGND
SENSE +
R1**
R NTC
R P
SENSE –
SGND
C1*
R2
*PLACE C1 NEAR SENSE + , R1||R2 × C1 =
SENSE – PINS
**PLACE R1 NEXT TO INDUCTOR
L
DCR
R SENSE(EQ) = DCR
R2
R1 + R2
3867 F03b
(3b) Using the Inductor DCR to Sense Current
Figure 3. Two Different Methods of Sensing Current
the sense resistor represented a relatively small error. For
today’s highest current density solutions, however, 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
up to 1MHz are becoming more common. Under these
conditions the voltage drop across the sense resistor’s
parasitic inductance is no longer negligible.
In previous generations of controllers, a small RC filter
placed near the IC was commonly used to reduce the ef-
fects of capacitive and inductive noise coupled 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 resis-
tive component of the current sense signal in the presence
of parasitic inductance. For example, Figure 4 illustrates
the voltage waveform across a 2mΩ sense resistor with
a 2010 footprint for a 1.2V/15A converter operating at
100% load. The waveform 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
3867f
15
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相关代理商/技术参数
参数描述
LTC3867IUF#PBF 功能描述:IC REG CTRLR BUCK PWM CM 24-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR)
LTC3867IUF#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 24-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR)
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LTC3868EGN-1#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR)
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