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参数资料
| 型号： | LTC3865IFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 21/38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： | 是 |
| 升压： | 无 |
| 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： | 38-TFSOP （0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3865/LTC3865-1
APPLICATIONS INFORMATION
When the master channel’s output experiences dynamic
excursion (under load transient, for example), the slave
channel output will be affected as well. For better output
regulation, use the coincident tracking mode instead of
ratiometric.
INTV CC Regulators and EXTV CC
The LTC3865 features a true PMOS LDO that supplies
power to INTV CC from the V IN supply. INTV CC powers the
gate drivers and much of the LTC3865/LTC3865-1’s internal
circuitry. The linear regulator regulates the voltage at the
INTV CC pin to 5V when V IN is greater than 5.5V. EXTV CC
connects to INTV CC through a P-channel MOSFET and can
supply the needed power when its voltage is higher than
4.7V. Each of these can supply a peak current of 80mA
and must be bypassed to ground with a minimum of 4.7μF
ceramic capacitor or low ESR electrolytic capacitor. No mat-
ter what type of bulk capacitor is used, an additional 0.1μF
ceramic capacitor placed directly adjacent to the INTV CC
and PGND pins is highly recommended. Good bypassing
is needed to supply the high transient currents required
by the MOSFET gate drivers and to prevent interaction
between channels.
High input voltage applications in which large MOSFETs are
being driven at high frequencies may cause the maximum
junction temperature rating for the LTC3865/LTC3865-1
to be exceeded. The INTV CC current, which is dominated
by the gate charge current, may be supplied by either the
5V linear regulator or EXTV CC . When the voltage on the
EXTV CC pin is less than 4.7V, the linear regulator is enabled.
Power dissipation for the IC in this case is highest and is
equal to V IN ? I INTVCC . The gate charge current is depen-
dent on operating frequency as discussed in the Ef?ciency
Considerations section. The junction temperature can be
estimated by using the equations given in Note 3 of the
Electrical Characteristics. For example, the LTC3865 INTV CC
current is limited to less than 42mA from a 38V supply in
the UH package and not using the EXTV CC supply:
T J = 70°C + (42mA)(38V)(34°C/W) = 125°C
To prevent the maximum junction temperature from being
exceeded, the input supply current must be checked while
operating in continuous conduction mode (MODE/PLLIN
EXTV CC rises above 4.7V, the INTV CC linear regulator is
turned off and the EXTV CC is connected to the INTV CC .
The EXTV CC remains on as long as the voltage applied to
EXTV CC remains above 4.5V. Using the EXTV CC allows the
MOSFET driver and control power to be derived from one
of the LTC3865/LTC3865-1’s switching regulator outputs
during normal operation and from the INTV CC when the
output is out of regulation (e.g., start-up, short-circuit). If
more current is required through the EXTV CC than is speci-
?ed, an external Schottky diode can be added between the
EXTV CC and INTV CC pins. Do not apply more than 6V to
the EXTV CC pin and make sure that EXTV CC < V IN .
Signi?cant ef?ciency and thermal gains can be realized by
powering INTV CC from the output, since the V IN current
resulting from the driver and control currents will be scaled
by a factor of (Duty Cycle)/(Switcher Ef?ciency).
Tying the EXTV CC pin to a 5V supply reduces the junction
temperature in the previous example from 125°C to:
T J = 70°C + (42mA)(5V)(34°C/W) = 77°C
However, for 3.3V and other low voltage outputs, addi-
tional circuitry is required to derive INTV CC power from
the output.
The following list summarizes the four possible connec-
tions for EXTV CC :
1. EXTV CC left open (or grounded). This will cause INTV CC
to be powered from the internal 5V regulator result-
ing in an ef?ciency penalty of up to 10% at high input
voltages.
2. EXTV CC connected directly to V OUT . This is the normal
connection for a 5V regulator and provides the highest
ef?ciency.
3. EXTV CC connected to an external supply. If a 5V external
supply is available, it may be used to power EXTV CC
providing it is compatible with the MOSFET gate drive
requirements.
4. EXTV CC connected to an output-derived boost network.
For 3.3V and other low voltage regulators, ef?ciency
gains can still be realized by connecting EXTV CC to an
output-derived voltage that has been boosted to greater
than 4.7V.
= SGND) at maximum V IN . When the voltage applied to
3865fb
21
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相关代理商/技术参数 |
参数描述 |
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| LTC3865IUH#PBF | 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) |
| LTC3865IUH#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) |
| LTC3865IUH-1#PBF | 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) |
| 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) |
| 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) |
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