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| 型号： | LTC1775CS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-SOIC |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 165kHz |
| 占空比： | 99% |
| 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： | 0°C ~ 70°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
LTC1775
APPLICATIO S I FOR ATIO
Automotive Considerations: Plugging into the
Cigarette Lighter
As battery-powered devices go mobile, there is a natural
interest in plugging into the cigarette lighter in order to
conserve or even recharge battery packs during opera-
tion. But before you connect, be advised: you are plug-
Design Example
As a design example, take a supply with the following
specifications: V IN = 6V to 22V (15V nominal), V OUT = 5V,
I O(MAX) = 10A. The required R DS(ON) can immediately be
estimated:
ging into the supply from hell. The main power line in an
automobile is the source of a number of nasty potential
R DS ( ON ) =
240 mV
( 10 A )( 1 . 3 )
= 0 . 018 ?
transients, including load dump, reverse and double
battery.
Load dump is the result of a loose battery cable. When the
cable breaks connection, the field collapse in the alternator
can cause a positive spike as high as 60V which takes
A 0.019 ? Siliconix SUD50N03-10 MOSFET ( θ JA =
30 ° C/W) is close to this value.
For 40% ripple current at maximum V IN the inductor
should be:
? 1 –
? = 6 . 4 μ H
severalhundredmillisecondstodecay.Reversebatteryis
just what it says, while double battery is a consequence of
tow truck operators finding that a 24V jump start cranks
L ≥
5 V ?
( 150 kHz )( 0 . 4 )( 10 A ) ?
5 V ?
22 V ?
cold engines faster than 12V.
The network shown in Figure 10 is the most straightfor-
ward approach to protect a DC/DC converter from the
Choosing a Magnetics 55380-A2 core with 8 turns of 15
gauge wire yields a 6 μ H inductor. The resulting maximum
ripple current will be:
? 1 –
? = 4 . 3 A
ravages of an automotive power line. The series diode
prevents current from flowing during reverse battery,
while the transient suppressor clamps the input voltage
? I L ( MAX ) =
5 V ?
( 150 kHz )( 6 μ H ) ?
5 V ?
22 V ?
during load dump. Note that the transient suppressor
should not conduct during double-battery operation, but
must still clamp the input voltage below breakdown of the
converter. Although the LTC1775 has a maximum input
Next, check that the minimum value of the current limit is
acceptable. Assume a junction temperature about 20 ° C
above the 70 ° C ambient with ρ 90 ° C = 1.3.
– ? ? 4 . 3 A = 10 A
voltageof36V,mostapplicationswillbelimitedto30Vby
the MOSFET V (BR)DSS .
I LIMIT ≥
300 mV ? 1 ?
( 0 . 019 ? )( 1 . 3 ) ? 2 ?
Now double-check the assumed T J :
( ) ( 1 . 3 ) ( 0 . 019 ? ) +
P TOP =
( )( ) ( )( )( )
V IN
LTC1775
PGND
50A I PK
RATING
TRANSIENT VOLTAGE
SUPPRESSOR
GENERAL INSTRUMENT
1.5KA24A
12V
5 V 2
10 A
22 V
2
1 . 7 22 V 10 A 170 pF 150 kHz
= 0 . 56 W + 0 . 21 W = 0 . 77 mW
18
1775 F10
Figure 10. Automotive Application Protection
T J = 70 ° C + (0.77W)(30 ° C/W) = 93 ° C
Since ρ (93 ° C) ? ρ (90 ° C), the solution is self-consistent.
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相关代理商/技术参数 |
参数描述 |
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| LTC1775IGN | 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 |
| LTC1775IGN#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:- 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 |
| LTC1775IGN#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 |
| LTC1775IGN#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 |
| LTC1775IS | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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 |
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