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参数资料
| 型号： | LTC3826IUH#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 585kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 36 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 ~ 85°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3826
APPLICATIONS INFORMATION
selected. As inductance increases, core losses go down.
Unfortunately, increased inductance requires more turns
operating in continuous mode the duty cycles for the top
and bottom MOSFETs are given by:
of wire and therefore copper losses will increase.
Ferrite designs have very low core loss and are preferred
at high switching frequencies, so design goals can con-
Main Switch Duty Cycle =
V OUT
V IN
V IN OUT
centrateoncopperlossandpreventingsaturation.Ferrite
core material saturates “hard,” which means that induc-
tance collapses abruptly when the peak design current is
Synchronous Switch Duty Cycle =
– V
V IN
( I MAX ) ( 1 +
) R DS(ON) +
P MAIN =
( V IN )
( R DR ) ( C MILLER ) ?
( ) f
exceeded. This results in an abrupt increase in inductor
ripple current and consequent output voltage ripple. Do
not allow the core to saturate!
Power MOSFET and Schottky Diode (Optional)
Selection
Two external power MOSFETs must be selected for each
controller in the LTC3826: one N-channel MOSFET for the
top (main) switch, and one N-channel MOSFET for the
bottom (synchronous) switch.
The MOSFET power dissipations at maximum output
current are given by:
V OUT 2
V IN
2 I MAX
2
1 1
+
V INTVCC – V THMIN V THMIN
( I MAX ) ( 1 +
Thepeak-to-peakdrivelevelsaresetbytheINTV CC voltage.
This voltage is typically 5V during start-up (see EXTV CC Pin
Connection). Consequently, logic-level threshold MOSFETs
P SYNC =
V IN – V OUT
V IN
2
) R DS(ON)
must be used in most applications. The only exception
is if low input voltage is expected (V IN < 5V); then, sub-
logic level threshold MOSFETs (V GS(TH) < 3V) should be
used. Pay close attention to the BV DSS speci?cation for
the MOSFETs as well; most of the logic level MOSFETs are
limited to 30V or less.
Selection criteria for the power MOSFETs include the “ON”
resistance R DS(ON) , Miller capacitance C MILLER , input
voltage and maximum output current. Miller capacitance,
C MILLER , can be approximated from the gate charge curve
usually provided on the MOSFET manufacturers’ data
sheet. C MILLER is equal to the increase in gate charge
along the horizontal axis while the curve is approximately
?at divided by the speci?ed change in V DS . This result is
then multiplied by the ratio of the application applied V DS
to the Gate charge curve speci?ed V DS . When the IC is
where δ is the temperature dependency of R DS(ON) and
R DR (approximately 2Ω) is the effective driver resistance
at the MOSFET’s Miller threshold voltage. V THMIN is the
typical MOSFET minimum threshold voltage.
Both MOSFETs have I 2 R losses while the topside N-channel
equation includes an additional term for transition losses,
which are highest at high input voltages. For V IN < 20V
the high current ef?ciency generally improves with larger
MOSFETs, while for V IN > 20V the transition losses rapidly
increase to the point that the use of a higher R DS(ON) device
with lower C MILLER actually provides higher ef?ciency. The
synchronous MOSFET losses are greatest at high input
voltage when the top switch duty factor is low or during
a short-circuit when the synchronous switch is on close
to 100% of the period.
3826fc
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3827EG-1 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 4V to 36V Input 28-Pin SSOP |
| LTC3827EG-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP 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:2,000 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) |
| LTC3827EG-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP 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 |
| LTC3827EUH#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:2,000 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) |
| LTC3827EUH#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: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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