参数资料
| 型号： | LTC3780EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 20/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 24-SSOP |
| 标准包装： | 59 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 99% |
| 电源电压： | 4 V ~ 36 V |
| 降压： | 是 |
| 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 ~ 85°C |
| 封装/外壳： | 24-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3780
APPLICATIONS INFORMATION
Schottky Diode (D1, D2) Selection
and Light Load Operation
The Schottky diodes D1 and D2 shown in Figure 13 conduct
during the dead time between the conduction of the power
MOSFET switches. They are intended to prevent the body
diode of synchronous switches B and D from turning on
and storing charge during the dead time. In particular, D2
significantly reduces reverse recovery current between
switch D turn-off and switch C turn-on, which improves
converter efficiency and reduces switch C voltage stress. In
order for the diode to be effective, the inductance between it
and the synchronous switch must be as small as possible,
mandating that these components be placed adjacently.
In buck mode, when the FCB pin voltage is 0.85 < V FCB
< 5V, the converter operates in skip-cycle mode. In this
mode, synchronous switch B remains off until the induc-
tor peak current exceeds one-fifth of its maximum peak
current. As a result, D1 should be rated for about one-half
to one-third of the full load current.
In boost mode, when the FCB pin voltage is higher than
5.3V, the converter operates in discontinuous current mode.
In this mode, synchronous switch D remains off until the
inductor peak current exceeds one-fifth of its maximum
peak current. As a result, D2 should be rated for about
one-third to one-fourth of the full load current.
In buck mode, when the FCB pin voltage is higher than 5.3V,
the converter operates in constant frequency discontinu-
ous current mode. In this mode, synchronous switch B
remains on until the inductor valley current is lower than
the sense voltage representing the minimum negative
inductor current level (V SENSE = –5mV). Both switch A
and B are off until next clock signal.
In boost mode, when the FCB pin voltage is 0.85 < V FCB
< 5.3V, the converter operates in Burst Mode operation.
In this mode, the controller clamps the peak inductor
current to approximately 20% of the maximum inductor
current. The output voltage ripple can increase during
Burst Mode operation.
INTV CC Regulator
An internal P-channel low dropout regulator produces 6V
at the INTV CC pin from the V IN supply pin. INTV CC powers
the drivers and internal circuitry within the LTC3780. The
INTV CC pin regulator can supply a peak current of 40mA
and must be bypassed to ground with a minimum of 4.7μF
tantalum, 10μF special polymer or low ESR type electrolytic
capacitor. A 1μF ceramic capacitor placed directly adjacent
to the INTV CC and PGND IC pins is highly recommended.
Good bypassing is necessary to supply the high transient
current required by MOSFET gate drivers.
Higher input voltage applications in which large MOSFETs
are being driven at high frequencies may cause the maxi-
mum junction temperature rating for the LTC3780 to be
exceeded. The system supply current is normally dominated
by the gate charge current. Additional external loading of
the INTV CC also needs to be taken into account for the
power dissipation calculations. The total INTV CC current
can be supplied by either the 6V internal linear regulator
or by the EXTV CC input pin. When the voltage applied to
the EXTV CC pin is less than 5.7V, all of the INTV CC current
is supplied by the internal 6V linear regulator. Power dis-
sipation for the IC in this case is V IN ? I INTVCC , and overall
efficiency is lowered. The junction temperature can be
estimated by using the equations given in Note 2 of the
Electrical Characteristics. For example, a typical applica-
tion operating in continuous current mode might draw
24mA from a 24V supply when not using the EXTV CC pin:
T J = 70°C + 24mA ? 24V ? 34°C/W = 90°C
Use of the EXTV CC input pin reduces the junction tem-
perature to:
T J = 70°C + 24mA ? 6V ? 34°C/W = 75°C
To prevent maximum junction temperature from being
exceeded, the input supply current must be checked op-
erating in continuous mode at maximum V IN .
3780ff
20
For more information www.linear.com/LTC3780
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| LTC3780EUH | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP |
| LTC3780EUH#PBF | 功能描述:IC REG CTRLR BST 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:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3780EUH#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC3780EUH#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP T/R |
| LTC3780EUH#TRPBF | 功能描述:IC REG CTRLR BST 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:- 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 |
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