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参数资料
| 型号： | LTC3865IUH#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 880 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封装： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD, QFN-32 |
| 文件页数： | 16/38页 |
| 文件大小： | 400K |
| 代理商： | LTC3865IUH#PBF |
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LTC3865/LTC3865-1
23
3865fb
APPLICATIONS INFORMATION
maximum RMS current of one channel must be used. The
maximum RMS capacitor current is given by:
C
quired I
I
V
VV
V
IN
RMS
MAX
IN
OUT
IN
OUT
Re
–
≈
()(
)
12
/
This formula has a maximum at VIN = 2VOUT, where
IRMS = IOUT/2. This simple worst-case condition is com-
monly used for design because even signicant deviations
do not offer much relief. Note that capacitor manufacturers’
ripple current ratings are often based on only 2000 hours
of life. This makes it advisable to further derate the capaci-
tor, or to choose a capacitor rated at a higher temperature
than required. Several capacitors may be paralleled to meet
size or height requirements in the design. Due to the high
operating frequency of the LTC3865, ceramic capacitors
can also be used for CIN. Always consult the manufacturer
if there is any question.
The benet of the LTC3865/LTC3865-1 2-phase operation
can be calculated by using the equation above for the higher
power controller and then calculating the loss that would
have resulted if both controller channels switched on at
the same time. The total RMS power lost is lower when
both controllers are operating due to the reduced overlap of
current pulses required through the input capacitor’s ESR.
This is why the input capacitor’s requirement calculated
above for the worst-case controller is adequate for the dual
controller design. Also, the input protection fuse resistance,
battery resistance, and PC board trace resistance losses
are also reduced due to the reduced peak currents in a
2-phase system. The overall benet of a multiphase design
will only be fully realized when the source impedance of the
power supply/battery is included in the efciency testing.
The sources of the top MOSFETs should be placed within
1cm of each other and share a common CIN(s). Separating
the sources and CIN may produce undesirable voltage and
current resonances at VIN.
A small (0.1μF to 1μF) bypass capacitor between the chip VIN
pin and ground, placed close to the LTC3865/LTC3865-1,
is also suggested. A 2.2Ω to 10Ω resistor placed between
CIN (C1) and the VIN pin provides further isolation between
the two channels.
The selection of COUT is driven by the effective series
resistance (ESR). Typically, once the ESR requirement
is satised, the capacitance is adequate for ltering. The
output ripple (
ΔVOUT) is approximated by:
Δ≈
+
V
I
ESR
fC
OUT
RIPPLE
OUT
1
8
where f is the operating frequency, COUT is the output
capacitance and IRIPPLE is the ripple current in the induc-
tor. The output ripple is highest at maximum input voltage
since IRIPPLE increases with input voltage.
Setting Output Voltage
The LTC3865/LTC3865-1 output voltages are each set
by the voltages at VID pins. Each of the VID pins can be
oated, or INTVCC or grounded, depending on what preset
voltages are needed at the output (Table 1).
If the desired output voltage is not one of the preset
values, select 0.6V and use 1% resistors to divide VOUT,
as shown in Figure 9. The regulated output voltage is
determined by:
VV
R
OUT
B
A
=+
06
1
.
To improve the frequency response, a feed-forward ca-
pacitor, CFF, may be used. Great care should be taken to
route the VOSENSE line away from noise sources, such as
the inductor or the SW line.
VOSENSE
VOUT
RB
RA
CFF
1/2 LTC3865
3865 F09
Figure 9. Setting Output Voltage
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相关代理商/技术参数 |
参数描述 |
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| LTC3866EFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 24TSSOP 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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3866EFE#PBF | 制造商:Linear Technology 功能描述:BUCK REGULATOR CURRENT MODE SYNC TSSOP |
| LTC3866EFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 24TSSOP 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) |
| LTC3866EUF#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) |
| LTC3866EUF#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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