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| 型号： | LTC1436AIGN-PLL |
| 厂商： | Linear Technology |
| 文件页数： | 22/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 24-SSOP |
| 标准包装： | 55 |
| 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： | -40°C ~ 85°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
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LTC1436A
LTC1436-PLL-A/LTC1437A
APPLICATIO N S I N FOR M ATIO N
R SENSE =
= 0 . 033 ?
? 1 . 37 ( 10 4 ) ?
C OSC = ? ? – 11 = 43 pF
?
?
Asecond,moreseveretransientiscausedbyswitchingin
loads with large (>1 μ F) supply bypass capacitors. The
discharged bypass capacitors are effectively put in parallel
with C OUT , causing a rapid drop in V OUT . No regulator can
deliver enough current to prevent this problem if the load
switch resistance is low and it is driven quickly. The only
solution is to limit the rise time of the switch drive so that
the load rise time is limited to approximately 25(C LOAD ).
Thus a 10 μ F capacitor would require a 250 μ s rise time,
limiting the charging current to about 200mA.
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 operation.
But before you connect, be advised: you are plugging into
the supply from hell. The main battery line in an automo-
bile is the source of a number of nasty potential transients,
including load dump, reverse battery, and double battery.
should not conduct during double battery operation, but
must still clamp the input voltage below breakdown of the
converter. Although the LTC1436A/LTC1437A have a maxi-
mum input voltage of 36V, most applications will be
limited to 30V by the MOSFET BV DSS .
Design Example
As a design example, assume V IN = 12V (nominal), V IN =
22V (max), V OUT = 1.6V, I MAX = 3A and f = 250kHz, R SENSE
and C OSC can immediately be calculated:
100 mV
3 A
? 250 ?
Refering to Figure 3, a 4.7 μ H inductor falls within the
recommended range. To check the actual value of the
ripple current the following equation is used:
( )( )
f L ?
1 ? OUT ?
Loaddumpistheresultofaloosebatterycable.Whenthe
cable breaks connection, the field collapse in the alternator
can cause a positive spike as high as 60V which takes
? I L =
V OUT ?
?
V ?
V IN ?
several hundred milliseconds to decay. Reverse battery is
just what it says, while double battery is a consequence of
The highest value of the ripple current occurs at the
maximum input voltage:
( )
?
C OSC pF = ?
( )
? Frequency kHz
?
tow-truck operators finding that a 24V jump start cranks
cold engines faster than 12V.
The network shown in Figure 14 is the most straightfor-
?
1 . 37 ( 10 4 )
?
? – 11
?
ward 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 dump. Note that the transient suppressor
The lowest duty cycle also occurs at maximum input
voltage. The on-time during this condition should be
checked to make sure it doesn’t violate the LTC1436A/
LTC1437A’s minimum on-time and cause cycle skipping
to occur. The required on-time at V IN(MAX) is:
( V IN ( MAX ) ) ( f )
12V
50A IPK RATING
V IN
LTC1436A
t ON ( MIN ) =
V OUT
=
1 . 6 V
( 22 V )( 250 kHz )
= 291 ns
TRANSIENT VOLTAGE
SUPPRESSOR
GENERAL INSTRUMENT
1.5KA24A
LTC1437A
The ? I L was previously calculated to be 1.3A, which is
43% of I MAX . From Figure 12, the LTC1436A/LTC1437A’s
minimum on-time at 43% ripple is about 235ns. There-
1436 F14
Figure 14. Automotive Application Protection
fore, the minimum on-time is sufficient and no cycle
skipping will occur.
14367afb
22
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| LTC1436AIGN#PBF | IC REG CTRLR BUCK PWM CM 24-SSOP |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1436AIGN-PLL#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-PLL#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 |
| LTC1436AIGN-PLL#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:4,500 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 |
| LTC1436CGN | 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 |
| LTC1436CGN#PBF | 制造商:Linear Technology 功能描述:Step-Down Switching Regulators |
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