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| 型号： | LTC1625IGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-SSOP |
| 标准包装： | 100 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 165kHz |
| 占空比： | 99% |
| 电源电压： | 3.9 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： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1333 (CN2011-ZH PDF) |
LTC1625
APPLICATIO N S I N FOR M ATIO N
automobile is the source of a number of nasty potential
transients, including load dump, reverse and double
For 40% ripple current at maximum V IN the inductor
should be:
( 225 kHz )( 0 . 4 )( 2 A ) ?
? = 16 μ H
battery.
Load dump is the result of a loose battery cable. When the
cable breaks connection, the field collapse in the alternator
L ≥
3 . 3 V ?
?
1 –
3 . 3 V ?
22 V ?
can cause a positive spike as high as 60V which takes
several hundred milliseconds to decay. Reverse battery is
just what it says, while double battery is a consequence of
Choosing a standard value of 15 μ H results in a maximum
ripple current of:
? 1 –
? = 0 . 83 A
tow truck operators finding that a 24V jump start cranks
cold engines faster than 12V.
The network shown in Figure 8 is the most straightforward
? I L ( MAX ) =
3 . 3 V ?
( 225 kHz )( 15 μ H ) ?
3 . 3 V ?
22 V ?
approach to protect a DC/DC converter from the ravages
of an automotive battery line. The series diode prevents
current from flowing during reverse battery, while the
transient suppressor clamps the input voltage during load
Next, check that the minimum value of the current limit is
acceptable. Assume a junction temperature close to a
70 ° C ambient with ρ 80 ° C = 1.3.
– ? ? 0 . 83 A = 2 . 3 A
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.
I LIMIT ≥
150 mV ? 1 ?
( 0 . 042 ? )( 1 . 3 ) ? 2 ?
Although the LTC1625 has a maximum input voltage of
36V, most applications will be limited to 30V by the
MOSFET V (BR)DSS .
This is comfortably above I O(MAX) = 2A. Now double-check
the assumed T J :
P TOP =
( 2 . 3 A ) ( 1 . 3 )( 0 . 042 ? ) +
( 1 . 7 )( 22 ) ( 2 . 3 A )( 180 pF )( 225 kHz )
LTC1625
V IN
50A I PK
RATING
TRANSIENT VOLTAGE
SUPPRESSOR
GENERAL INSTRUMENT
12V
3. 3V 2
22 V
2
= 43 mW + 77 mW = 120 mW
PGND
1.5KA24A
T J = 70 ° C + (120mW)(50 ° C/W) = 76 ° C
1625 F08
Figure 8. Automotive Application Protection
Since ρ (76 ° C) ? ρ (80 ° C), the solution is self-consistent.
A short circuit to ground will result in a folded back
current of:
+ ? ?
Design Example
As a design example, take a supply with the following
specifications: V IN = 12V to 22V (15V nominal), V OUT =
I SC =
30 mV ? 1 ? (15V )(0. 5 μ s)
( 0 . 03 ? )( 1 . 1 ) ? 2 ? 15 μ H
= 1 . 2 A
3.3V, I O(MAX) = 2A, and f = 225kHz. The required R DS(ON)
can immediately be estimated:
with a typical value of R DS(ON) and ρ (50 ° C) = 1.1. The
resulting power dissipated in the bottom MOSFET is:
( 1 . 2 A ) ( 1 . 1 )( 0 . 03 ? ) = 37 mW
R DS ( ON ) =
120 mV
( 2 A )( 1 . 3 )
= 0 . 046 ?
P BOT =
15V – 3 .3V
15 V
2
A 0.042 ? Siliconix Si4412DY MOSFET ( θ JA = 50 ° C/W) is
which is less than under full load conditions.
close to this value.
17
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| LTC1625IS | 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 |
| LTC1625IS#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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 |
| LTC1625IS#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN REGULATOR 16-SOIC |
| LTC1625IS#TR | 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 |
| LTC1625IS#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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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