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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： | 19/38页 |
| 文件大小： | 400K |
| 代理商： | LTC3865IUH#PBF |
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LTC3865/LTC3865-1
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3865fb
APPLICATIONS INFORMATION
Supplying INTVCC power through EXTVCC from an
output-derived source will scale the VIN current re-
quired for the driver and control circuits by a factor
of (Duty Cycle)/(Efciency). For example, in a 20V
to 5V application, 10mA of INTVCC current results in
approximately 2.5mA of VIN current. This reduces the
mid-current loss from 10% or more (if the driver was
powered directly from VIN) to only a few percent.
3. I2R losses are predicted from the DC resistances of the
fuse (if used), MOSFET, inductor, current sense resistor.
In continuous mode, the average output current ows
through L and RSENSE, but is “chopped” between the
topside MOSFET and the synchronous MOSFET. If the
two MOSFETs have approximately the same RDS(ON),
then the resistance of one MOSFET can simply be
summed with the resistances of L and RSENSE to obtain
I2R losses. For example, if each RDS(ON) = 10mΩ, RL =
10mΩ, RSENSE = 5mΩ, then the total resistance is
25mΩ. This results in losses ranging from 2% to 8%
as the output current increases from 3A to 15A for
a 5V output, or a 3% to 12% loss for a 3.3V output.
Efciency varies as the inverse square of VOUT for the
same external components and output power level. The
combined effects of increasingly lower output voltages
and higher currents required by high performance digital
systems is not doubling but quadrupling the importance
of loss terms in the switching regulator system!
4. Transition losses apply only to the topside MOSFET(s),
and become signicant only when operating at high
input voltages (typically 15V or greater). Transition
losses can be estimated from:
Transition Loss = (1.7) VIN2 IO(MAX) CRSS f
Other “hidden” losses such as copper trace and internal
battery resistances can account for an additional 5% to
10% efciency degradation in portable systems. It is
very important to include these “system” level losses
during the design phase. The internal battery and fuse
resistance losses can be minimized by making sure that
CIN has adequate charge storage and very low ESR at the
switching frequency. A 25W supply will typically require a
minimum of 20μF to 40μF of capacitance having a max-
imum of 20mΩ to 50mΩ of ESR. The LTC3865 2-phase
architecture typically halves this input capacitance require-
ment over competing solutions. Other losses including
Schottky conduction losses during dead time and induc-
tor core losses generally account for less than 2% total
additional loss.
Checking Transient Response
The regulator loop response can be checked by looking at
the load current transient response. Switching regulators
take several cycles to respond to a step in DC (resistive)
load current. When a load step occurs, VOUT shifts by an
amount equal to
ΔILOAD (ESR), where ESR is the effective
series resistance of COUT. ΔILOAD also begins to charge or
discharge COUT generating the feedback error signal that
forces the regulator to adapt to the current change and
return VOUT to its steady-state value. During this recovery
time VOUT can be monitored for excessive overshoot or
ringing, which would indicate a stability problem. The
availability of the ITH pin not only allows optimization of
control loop behavior but also provides a DC coupled and
AC ltered closed loop response test point. The DC step,
rise time and settling at this test point truly reects the
closed loop response. Assuming a predominantly second
order system, phase margin and/or damping factor can be
estimated using the percentage of overshoot seen at this
pin. The bandwidth can also be estimated by examining the
rise time at the pin. The ITH external components shown
in the Typical Application circuit will provide an adequate
starting point for most applications.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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