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| 型号： | LTC1909-8EG |
| 厂商： | Linear Technology |
| 文件页数： | 15/32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
OPERATIO
(Refer to Functional Diagram)
It uses two pins, SCL and SDA to communicate with a
master device through the Read Word and Write Word
protocols. The V IL and V IH logic threshold voltages of the
SDA and SCL pins are 0.8V and 2.1V respectively, which
comply with Rev 1.1 version of the Intel System Manage-
ment Bus Specifications. Both pins require a resistor or
active pull-up (see the LTC1694 data sheet) to V CC . Data is
has a trip point of 1.3V with ± 50mV of hysteresis. It is TTL
compatible and has a 2.5 μ A pull-up to V CC . Pulling VRON
low will force CPUON low immediately, regardless of the
On/Off state machine. Pulling VRON high or allowing it to
float high hands control to the On/Off state machine.
Table 1 summarizes the function of the control pins. The
SMBON control bit is explained in the next section.
clocked out of the SDA pin at the falling edge and latched
in at the rising edge of the SCL clock signal. The slave
address of the interface for both Read and Write protocols
is fixed at E2H.
Table 1. DC/DC Converter Control Pins
VRON SMBON DCON
0 X 1
1 0 1
PGTMR
0
0
CPUON
0
0
There are three types of Write Word protocols: Setup, On
1
↑
↓
0 for 50 μ s
Z (Note 2)
and Off and one Read Word protocol called Read-Back.
The Setup Write Word protocol is used to set up two
internal 5-bit registers (Register 0 and Register 1) with
alternate resistor divider DAC settings. The On and Off
Write Word protocols do not modify register contents but
↑ 1 ↓
Note 1: Also triggered by SEL pin toggling.
Note 2: Z = High Impedance
(Note 1)
0 for 50 μ s
(Note 1)
Z (Note 2)
are used to shutdown the converter or to allow it to soft-
start. The Read Word protocol is used to verify the
contents of the registers as well as to check whether the
converter is operating or in shutdown from a status bit
(DCON). Table 3 in the Applications Information section
shows the data bits that identify each protocol as Setup,
On, Off or Read-Back.
Controller Control
The VID programmer provides the VRON and CPUON pins
for the purpose of shutting down or allowing the converter
to soft-start. CPUON is an open-drain, N-channel output
pin that is normally tied to the RUN/SS pin of the controller
along with its soft-start capacitor. If the N-channel is turned
off, the pin enters a high impedance state and the capacitor
is allowed to charge up and soft-start the converter. When
shutting down the converter, the N-channel FET at the
CPUON pin will typically discharge a 0.1 μ F soft-start ca-
pacitor from 3V to 0.35V in 21 μ s with V CC = 2.7V. On
power-up, the power-on reset (POR) circuit in the SMBus
VID programmer turns on the N-channel to shut down the
converter. The CPUON pin can also be controlled to clear
overcurrent faults in the switching regulator (see Soft-
Start and Latchoff with the RUN/SS Pin section).
The CPUON pin is under the control of an internal On/Off
state machine that is accessed using the SMBus On/Off
Write Word protocols and the VRON pin. The VRON pin
The LTC1909-8 provides safeguards against incorrect di-
vider codes and the unintentional turn-on or turn-off of the
DC/DC converter. Incorrect codes due to bus conflicts
during Setup protocols can cause damage to circuits pow-
ered by the DC/DC converter. The safeguards built into the
LTC1909-8 include Read-Back, repeated On and Off pro-
tocols, ignoring On protocols if the registers have not been
set up (since power-up), locking out registers while the
DC/DC converters are operating and latching in VID codes
only in Setup protocols.
After power-up, the microprocessor must set up the reg-
isters before the LTC1909-8 recognizes On protocols. This
requirement ensures that the correct DC/DC converter out-
put is programmed before the converters are turned on.
After setup, Read-Back allows the contents of Registers 0
and 1 to be verified in case the VID codes were corrupted
by noise or bus conflicts.
In order to turn on the DC/DC converter, two On protocols
must be sent to slave address E2H without any other (E2H)
protocols in between. Protocols to other slave addresses
are still allowed and are ignored. Similarly, two Off proto-
cols must be sent to slave address E2H to turn the convert-
ers off. The On and Off protocols are monitored by an
internal state machine. The output of the state machine,
SMBON, is high after two On commands and low after two
Off commands. Repeated On and Off protocols reduce the
chances of bus conflicts and noise turning the converter
19098f
15
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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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