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| 型号： | LTC3880EUJ#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 44/112页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 40-QFN |
| 软件下载： | LTpowerPlay™ |
| 标准包装： | 61 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 1MHz |
| 电源电压： | 4.5 V ~ 24 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 ~ 105°C |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3880/LTC3880-1
APPLICATIONS INFORMATION
V IN
R VIN
1?
+
C IN
theendofthefalltimeinterval.IftheTOFF_FALLtimeis
set shorter than the time required to discharge the load
capacitance, the output will not reach the desired zero volt
state. At the end of TOFF_FALL, the controller will cease
to sink current and V OUT will decay at the natural rate
determined by the load impedance. If the controller is in
discontinuous mode, the controller will not pull negative
current and the output will be pulled low by the load, not
the power stage. The maximum fail time is limited to 1.3
seconds. The shorter TOFF_FALL time is set, the more
jagged the TOFF_FALL ramp will appear. The number of
steps in the ramp is equal to TOFF_FALL/0.1ms.
INTV CC REGULATOR
The LTC3880 features an NPN linear regulator that sup-
plies power to INTV CC from the V IN supply. INTV CC powers
the gate drivers, V DD33 and much of the LTC3880 internal
circuitry. The linear regulator produces the voltage at the
INTV CC pin to nominally 5V when V IN is greater than 6.5V.
The regulator can supply a peak current of 100mA and must
be bypassed to ground with a minimum of 1μF ceramic
capacitor or low ESR electrolytic capacitor. No matter 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 the chan-
nels. The NPN linear regulator on the LTC3880-1 is not
present and an external 5V supply is needed.
High input voltage application in which large MOSFETs
are being driven at high frequencies may cause the maxi-
mum junction temperature rating for the LTC3880 to be
exceeded. The INTV CC current, of which a large percent-
age is due to the gate charge current, may be supplied by
either the internal 5V linear regulator or from an external
5V regulator on the LTC3880-1. If the LTC3880 is used
with the internal regulator activated, the power through
the IC is equal to V IN ? I INTVCC . The gate charge current
is dependent on operating frequency as discussed in the
Efficiency Considerations section. The junction tempera-
ture can be estimated by using the equations in Note 2 of
the Electrical Characteristics. For example, the LTC3880
INTV CC current is limited to less than 69mA from a 24V
supply:
T J = 70°C + 69mA ? 24V ? 33°C/W = 125°C
To prevent the maximum junction temperature from being
exceeded, a LTC3880-1 can be used. In the LTC3880-1,
the INTV CC linear regulator is disabled and approximately
2mA of current is supplied internally from V IN . Significant
system efficiency and thermal gains can be realized by
powering the EXTV CC pin from a switching 5V regulator.
The V IN current resulting from the gate driver and control
circuitry will be scaled by a factor of:
? V EXTVCC ? ? 1 ?
? ? ? ?
? V IN ? ? Efficiency ?
Tying the EXTV CC pin to a 5V supply (LTC3880-1 only)
reduces the junction temperature in the previous example
from125°C to:
T J = 70°C + 69mA ? 5V ? 33°C/W + 2mA ? 24V ? 33°C/W
= 83°C
Do not tie INTV CC on the LTC3880 to an external supply
because INTV CC will attempt to pull the external supply
high and hit current limit, significantly increasing the die
temperature.
For applications where V IN is 5V, tie the V IN and INTV CC pins
together and tie the combined pins to the 5V input with a
1Ω or 2.2Ω resistor as shown in Figure 23. To minimize the
voltage drop caused by the gate charge current a low ESR
capacitor must be connected to the V IN /INTV CC (EXTV CC )
pins. This configuration will override the INTV CC (EXTV CC )
linear regulator and will prevent INTV CC (EXTV CC ) from
dropping too low. Make sure the INTV CC (EXTV CC ) voltage
exceeds the R DS(ON) test voltage for the MOSFETs which is
LTC3880
LTC3880-1
INTV CC /EXTV CC 5V
C INTVCC
4.7μF
3880 F23
Figure 23. Setup for a 5V Input
3880fb
44
For more information www.linear.com/LTC3880
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相关代理商/技术参数 |
参数描述 |
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| LTC3880IUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3880IUJ#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3880IUJ-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3880IUJ-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3883EUH#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL 24V 1MHZ 0.5/5.5V 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, 24V, 1MHZ, 0.5/5.5V, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 1MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:30A, Supply Voltage Min:4.5V, Supply Voltage Max:24V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:1MHz, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
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