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参数资料
| 型号： | LTC1909-8EG |
| 厂商： | Linear Technology |
| 文件页数： | 29/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 47 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 200kHz |
| 占空比： | 90% |
| 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： | -40°C ~ 85°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 其它名称： | LTC19098EG |
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LTC1909-8
APPLICATIO S I FOR ATIO
Each data byte is acknowledged in turn for all three Write
Word protocols but is only latched into Register 0 or 1 in
Setup protocol. This prevents previously loaded settings
from accidentally being changed. The first or Data Low
byte is loaded into Register 0. The second or Data High
byte is loaded into Register 1. After issuing the final
acknowledgment bit, the SMBus interface returns to an
idle state and waits for the next start bit.
Read Word Protocol
The Read Word protocol starts off like Write Word proto-
col but after the command code acknowledgment, the
microprocessor issues a second start bit (called a re-
peated start). This is followed by the slave address but with
the R/W bit set high to indicate that data direction is now
from the LTC1909-8 to the microprocessor. The LTC1909-8
then acknowledges the slave address and clocks the
contents of Register 0 (Data Low byte) to the micropro-
cessor. The Data Low byte is acknowledged by the micro-
processor. On detecting the acknowledgment bit, the
LTC1909-8 clocks out the contents of Register 1 (Data
High byte). As defined in the SMBus specifications, the
microprocessor does not acknowledge the last data byte.
The LTC1909-8 enters an idle state to wait for the next start
bit after clocking out the Data High byte. The five most
significant bits (VID0-VID4) of the Data Low and High
bytes are the resistor divider settings previously loaded
using the Setup protocol. The next bit below the VID0-
VID4 bits is the status of the DCON signal. If this bit is low
(high), the DC/DC converters are switched on (off). The
two unused, least significant bits of the Data Low and Data
High bytes are clocked out as zeros to eliminate the need
to mask out these bits in software.
Operating Sequence
A typical control sequence for the LTC1909-8 is as follows:
? On power up, the DCON bit is preset to a high state by
the power-on reset (POR) circuit. The CPUON pin is
pulled low to shut down the DC/DC converter. PGTMR
and PGOOD pull low to indicate that the converters are
not in regulation.
? Pull VRON low as a precaution. Take SEL high or low to
select the divider setting; e.g., one that suits the existing
power source (battery or wall-pack) or intended CPU
speed.
? Use the Setup protocol to load the appropriate divider
settings in Registers 0 and 1 and enable the On/Off state
machine.
? Use the Read-Back protocol to verify the contents of
Registers 0 and 1.
? Repeat the setup and read-back if the codes are incor-
rect (due to bus conflicts).
? Send two On protocols in succession to clear the DCON
bit.
? Use the Read-Back protocol to verify that the DCON is
low. A high state will indicate that an On command code
was corrupted by bus conflicts.
? Pull VRON high. Since DCON = 0, the CPUON pin enters
a high impedance state, allowing the DC/DC converter
to soft-start. PGTMR stays low for 50 μ s. PGOOD stays
low until the regulator output rises above the –7.5%
regulation limit.
? To shut down the supply, send two Off protocols to set
the DCON bit high or pull VRON low if immediate
shutdown is required.
19098f
29
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| LTC1909-8EG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-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 |
| LTC1909-8EG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-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 |
| LTC1909-8EG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-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 |
| LTC1911EMS8-1.5#PBF | 功能描述:IC REG BUCK 1.5V 0.25A 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1911EMS8-1.5#TR | 功能描述:IC REG BUCK 1.5V 0.25A 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
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