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参数资料
| 型号： | LTC1876EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 28/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 36-SSOP |
| 标准包装： | 37 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 3 |
| 频率 - 最大： | 360kHz |
| 占空比： | 99.4% |
| 电源电压： | 3.5 V ~ 36 V |
| 降压： | 是 |
| 升压： | 是 |
| 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： | 36-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1333 (CN2011-ZH PDF) |
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LTC1876
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 operation.
But before you connect, be advised: you are plugging into
the supply from hell. The main battery line in an automobile
is the source of a number of nasty potential transients,
including load-dump, reverse-battery, and double-bat-
tery.
Design Example
As a design example for one channel, assume V IN = 12V
(nominal), V IN = 22V(max), V OUT = 1.8V, I MAX = 5A, and
f = 300kHz, R SENSE can immediately be calculated:
R SENSE = 50mV/5A = 0.01 ?
Tie the FREQSET pin to the INTV CC pin for 300kHz opera-
tion.
Assume a 4.7 μ H inductor and check the actual value of the
ripple current. The following equation is used:
( f )( L ) ?
1 – OUT ?
Load-dumpistheresultofaloosebatterycable.Whenthe
cable breaks connection, the field collapse in the alternator
can cause a positive spike as high as 60V which takes
several hundred milliseconds to decay. Reverse-battery is
? I L =
V OUT ?
?
V ?
V IN ?
just what it says, while double-battery is a consequence of
tow-truck operators finding that a 24V jump start cranks
The highest value of the ripple current occurs at the
maximum input voltage:
? 1 –
? = 1 . 17 A
cold engines faster than 12V.
The network shown in Figure 12 is the most straight
forward approach to protect a DC/DC converter from the
? I L =
1 . 8 V ?
300 kHz ( 4 . 7 μ H ) ?
1 . 8 V ?
22 V ?
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
should not conduct during double-battery operation, but
must still clamp the input voltage below breakdown of the
converter. Although the LTC1876 step-down controllers
have a maximum input voltage of 36V, most applications
The ripple current is 23% of maximum output current,
which is below the 30% guideline. This means that a 3.3 μ H
inductor can be used.
Increasing the ripple current will also help ensure that the
minimum on-time of 200ns is not violated. The minimum
on-time occurs at maximum V IN :
will be limited to 30V by the MOSFET BVDSS.
t ON ( MIN ) =
V OUT
V IN ( MAX ) f
=
1 . 8 V
22 V ( 300 kHz )
= 273 ns
12V
50A I PK RATING
V IN
LTC1876
Since the output voltage is below 2.4V the output resistive
divider will need to be sized to not only set the output
voltage but also to absorb the SENSE pins current.
TRANSIENT VOLTAGE
SUPPRESSOR
R 1 MAX ) = 24 k ? ?
GENERAL INSTRUMENT
1.5KA24A
1876 F09
? 0 . 8 V ?
? 2 . 4 V – V OUT ?
= 24 k ? ? = 32 k
Figure 12. Automotive Application Protection
? 0 . 8 V ?
? 2 . 4 V – 1 . 8 V ?
1876fa
28
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1877EMS8 | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1877EMS8#PBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC1877EMS8#TR | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1877EMS8#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1877EMS8PBF | 制造商:Linear Technology 功能描述:1.5A Regulator Step Down LTC1877EMS8 |
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