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参数资料
| 型号： | LTC1625CS#TR |
| 厂商： | Linear Technology |
| 文件页数： | 9/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 165kHz |
| 占空比： | 99% |
| 电源电压： | 3.7 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： | 0°C ~ 70°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
LTC1625
APPLICATIO N S I N FOR M ATIO N
The basic LTC1625 application circuit is shown in Figure 1.
External component selection is primarily determined by
the maximum load current and begins with the selection of
the sense resistance and power MOSFETs. Because the
LTC1625 uses MOSFET V DS sensing, the sense resistance
is the R DS(ON) of the MOSFETs. The operating frequency
and the inductor are chosen based largely on the desired
amount of ripple current. Finally, C IN is selected for its
ability to handle the large RMS current into the converter
and C OUT is chosen with low enough ESR to meet the
output voltage ripple specification.
Power MOSFET Selection
The LTC1625 requires two external N-channel power
MOSFETs, one for the top (main) switch and one for the
bottom (synchronous) switch. Important parameters for
the power MOSFETs are the breakdown voltage V (BR)DSS ,
threshold voltage V GS(TH) , on-resistance R DS(ON) , reverse
transfer capacitance C RSS and maximum current I D(MAX) .
The ρ T is a normalized term accounting for the significant
variation in R DS(ON) with temperature, typically about
0.4%/ ° C as shown in Figure 2. Junction to case tempera-
ture T JC is around 10 ° C in most applications. For a
maximum ambient temperature of 70 ° C, using ρ 80 ° C ? 1.3
in the above equation is a reasonable choice. This equation
is plotted in Figure 3 to illustrate the dependence of
maximum output current on R DS(ON) . Some popular
MOSFETs from Siliconix are shown as data points.
2.0
1.5
1.0
0.5
The gate drive voltage is set by the 5.2V INTV CC supply.
0
– 50
0
50
100
150
Consequently, logic level threshold MOSFETs must be
used in LTC1625 applications. If low input voltage opera-
tion is expected (V IN < 5V), then sub-logic level threshold
MOSFETs should be used. Pay close attention to the
V (BR)DSS specification for the MOSFETs as well; many of
the logic level MOSFETs are limited to 30V or less.
10
JUNCTION TEMPERATURE ( ° C)
1625 F02
Figure 2. R DS(ON) vs Temperature
The MOSFET on-resistance is chosen based on the
required load current. The maximum average output cur-
rent I O(MAX) is equal to the peak inductor current less half
the peak-to-peak ripple current ? I L . The peak inductor
current is inherently limited in a current mode controller
by the current threshold I TH range. The corresponding
maximum V DS sense voltage is about 150mV under nor-
8
6
4
2
Si4420
Si4410
Si4412
Si9936
mal conditions. The LTC1625 will not allow peak inductor
current to exceed 150mV/R DS(ON)(TOP) . The following
equation is a good guide for determining the required
R DS(ON)(MAX) at 25 ° C (manufacturer’s specification), al-
lowing some margin for ripple current, current limit and
variations in the LTC1625 and external component values:
0
0 0.02 0.04 0.06 0.08 0.10
R DS(ON) ( ? )
1625 F03
Figure 3. Maximum Output Current vs R DS(ON) at V GS = 4.5V
The power dissipated by the top and bottom MOSFETs
R DS ( ON )( MAX ) ?
120 mV
( I O ( MAX ) )( ρ T )
strongly depends upon their respective duty cycles and
the load current. When the LTC1625 is operating in con-
tinuous mode, the duty cycles for the MOSFETs are:
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1625IGN | 功能描述:IC REG CTRLR BUCK PWM CM 16-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 |
| LTC1625IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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 |
| LTC1625IGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-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 |
| LTC1625IGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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 |
| LTC1625IGNPBF | 制造商:Linear Technology 功能描述:No RSENSE Current Mode Regulator SSOP16 |
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