参数资料
型号: LTC3865IFE#TRPBF
厂商: Linear Technology
文件页数: 14/38页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM CM 38TSSOP
标准包装: 2,000
系列: PolyPhase®
PWM 型: 电流模式
输出数: 2
频率 - 最大: 880kHz
占空比: 95%
电源电压: 4.5 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: 38-TFSOP (0.173",4.40mm 宽)裸露焊盘
包装: 带卷 (TR)
LTC3865/LTC3865-1
OPERATION
bad mask is 100μs when there are any VID transitions.
On the LTC3865-1 (UH32 package) or the LTC3865 (FE38
package), each channel has its own PGOOD pin. Therefore,
the PGOOD pins now only respond to their own channels.
The PGOOD pins are allowed to be pulled up by external
resistors to sources of up to 6V.
Output Overvoltage Protection
Output Voltage Programming
The output voltages of both channels of the LTC3865/
LTC3865-1 can be programmed to a preset value. There
are two VID pins for each channel and by connecting these
pins to INTV CC , GND, or by ?oating them, the output volt-
ages can be set to the values in Table 1.
Table 1. Programming of Output Voltage
An overvoltage comparator, OV, guards against transient
overshoots (>10%) as well as other more serious condi-
tions that may overvoltage the output. In such cases,
the top MOSFET is turned off and the bottom MOSFET is
turned on until the reverse current limit for the overvoltage
condition is reached. The bottom MOSFET will be turned on
again at the next clock and be turned off when the reverse
current limit is reached again. This process repeats until
the overvoltage condition is cleared.
VID11/VID21
INTV CC
INTV CC
INTV CC
Float
Float
Float
GND
GND
GND
VID12/VID22
INTV CC
Float
GND
INTV CC
Float
GND
INTV CC
Float
GND
V OUT1 /V OUT2 (V)
5.0
3.3
2.5
1.8
0.6 or External Divider
1.5
1.2
1.0
1.1
APPLICATIONS INFORMATION
The Typical Application on the ?rst page is a basic LTC3865
application circuit. The LTC3865 can be con?gured to use
either DCR (inductor resistance) sensing or low value resis-
tor sensing. The choice between the two current sensing
schemes is largely a design trade-off between cost, power
consumption and accuracy. DCR sensing is becoming
popular because it saves expensive current sensing resis-
tors and is more power ef?cient, especially in high current
applications. However, current sensing resistors provide
the most accurate current limits for the controller. Other
external component selection is driven by the load require-
ment, and begins with the selection of R SENSE (if R SENSE is
used) and inductor value. Next, the power MOSFETs are se-
lected. Finally, input and output capacitors are selected.
Current Limit Programming
The I LIM pin is a tri-level logic input which sets the maxi-
mum current limit of the controller. When I LIM is either
grounded, ?oated or tied to INTV CC , the typical value for
the maximum current sense threshold will be 30mV, 50mV
Which setting should be used? For the best current limit
accuracy, use the 75mV setting. The 30mV setting will
allow for the use of very low DCR inductors or sense
resistors, but at the expense of current limit accuracy.
The 50mV setting is a good balance between the two. For
single output dual phase applications, use the 50mV or
75mV setting for optimal current sharing.
SENSE + and SENSE – Pins
The SENSE + and SENSE – pins are the inputs to the current
comparators. The common mode input voltage range of
the current comparators is 0V to 5V. Both SENSE pins
are high impedance inputs with small base currents of
less than 1μA. When the SENSE pins ramp up from 0V to
1.4V, the small base currents ?ow out of the SENSE pins.
When the SENSE pins ramp down from 5V to 1.1V, the
small base currents ?ow into the SENSE pins. The high
impedance inputs to the current comparators allow ac-
curate DCR sensing. However, care must be taken not to
?oat these pins during normal operation.
or 75mV, respectively.
3865fb
14
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LTC3865IUH-1#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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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