- 您现在的位置：买卖IC网 > PDF目录15258 > LTC1436ACGN-PLL#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 24-SSOP PDF资料下载
参数资料
| 型号： | LTC1436ACGN-PLL#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 24-SSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 138kHz |
| 占空比： | 99% |
| 电源电压： | 3.5 V ~ 30 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： | 0°C ~ 70°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页当前第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页
LTC1436A
LTC1436A-PLL/LTC1437A
APPLICATIO N S I N FOR M ATIO N
V OUT
( V
)
( ) ( )
P MAIN = OUT I MAX DS ( ON )
1 + δ R
( ) ( I MAX )( C RSS )( f )
+ k V IN
P SYNC = IN OUT ( I MAX ) ( ) R DS ( ON )
V ? V
1 + δ
Inductor Core Selection
Once the value for L is known, the type of inductor must
be selected. High efficiency converters generally cannot
afford the core loss found in low cost powdered iron
cores, forcing the use of more expensive ferrite,
molypermalloy, or Kool M μ ? cores. Actual core loss is
independent of core size for a fixed inductor value, but it
is very dependent on inductance selected. As inductance
increases, core losses go down. Unfortunately, increased
inductance requires more turns of wire and therefore
copper losses will increase.
Ferrite designs have very low core loss and are prefered at
high switching frequencies, so design goals can concen-
trate on copper loss and preventing saturation. Ferrite
core material saturates “hard,” which means that induc-
tance collapses abruptly when the peak design current is
exceeded. This results in an abrupt increase in inductor
ripple current and consequent output voltage ripple. Do
not allow the core to saturate!
Molypermalloy (from Magnetics, Inc.) is a very good, low
loss core material for toroids, but it is more expensive than
ferrite. A reasonable compromise from the same manu-
facturer is Kool M μ . Toroids are very space efficient,
especially when you can use several layers of wire.
Because they generally lack a bobbin, mounting is more
difficult. However, designs for surface mount are available
which do not increase the height significantly.
Power MOSFET and D1 Selection
Three external power MOSFETs must be selected for use
with the LTC1436A/LTC1437A: a pair of N-channel MOS-
FETs for the top (main) switch and an N-channel MOSFET
for the bottom (synchronous) switch.
To take advantage of the Adaptive Power output stage, two
topside MOSFETs must be selected. A large (low R SD(ON) )
MOSFET and a small (higher R DS(ON) ) MOSFET are
required. The large MOSFET is used as the main switch
and works in conjunction with the synchronous switch.
The smaller MOSFET is only enabled under low load
current conditions. This increases midcurrent efficiencies
while continuing to operate at constant frequency. Also, by
using the small MOSFET the circuit can maintain constant
frequency operation down to lower currents before cycle
skipping occurs.
The R DS(ON) recommended for the small MOSFET is
around 0.5 ? . Be careful not to use a MOSFET with an
R DS(ON) that is too low; remember, we want to conserve
gate charge. (A higher R DS(ON) MOSFET has a smaller gate
capacitance and thus requires less current to charge its
gate). For cost sensitive applications the small MOSFET
can be removed. The circuit will then begin Burst Mode
operation as the load current is dropped.
The peak-to-peak gate drive levels are set by the INTV CC
voltage. This voltage is typically 5V during start-up (see
EXTV CC Pin Connection). Consequently, logic level
threshold MOSFETs must be used in most LTC1436A/
LTC1437A applications. The only exception is applications
in which EXTV CC is powered from an external supply
greater than 8V (must be less than 10V), in which standard
threshold MOSFETs [V GS(TH) < 4V] may be used. Pay close
attention to the BV DSS specification for the MOSFETs as
well; many of the logic level MOSFETs are limited to 30V
or less.
Selection criteria for the power MOSFETs include the “ON”
resistance R SD(ON) , reverse transfer capacitance C RSS ,
input voltage and maximum output current. When the
LTC1436A/LTC1437A are operating in continuous mode
the duty cycles for the top and bottom MOSFETs are
given by:
Main Switch Duty Cycle =
V IN
IN ? V OUT
Synchronous Switch Duty Cycle =
V IN
The MOSFET power dissipations at maximum output
current are given by:
V 2
V IN
1 . 85
2
V IN
Kool M μ is a registered trademark of Magnetics, Inc.
14367afb
13
相关PDF资料 |
PDF描述 |
|---|---|
| VE-B5V-EV-F4 | CONVERTER MOD DC/DC 5.8V 150W |
| LTC1628IG#TRPBF | IC REG CTRLR BUCK PWM CM 28-SSOP |
| VE-B5V-EV-F2 | CONVERTER MOD DC/DC 5.8V 150W |
| URZ1C332MHD | CAP ALUM 3300UF 16V 20% RADIAL |
| VE-B5W-EV-F4 | CONVERTER MOD DC/DC 5.5V 150W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1436AEGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1436AEGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1436AIGN | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP RoHS:否 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 |
| LTC1436AIGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP 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 |
| LTC1436AIGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP RoHS:否 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 |
发布紧急采购，3分钟左右您将得到回复。