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参数资料
| 型号： | LTC4222CUH#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC32 |
| 封装： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD-X, QFN-32 |
| 文件页数： | 14/32页 |
| 文件大小： | 280K |
| 代理商： | LTC4222CUH#TRPBF |
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LTC4222
21
4222fa
APPLICATIONS INFORMATION
The address is set with the help of Table 1, which indi-
cates binary address 1000111 corresponds to address
4. Address 4 is set by setting ADR2 low, ADR1 open and
ADR0 high.
Next the value of R5 and R6 are chosen to be the default
values 10Ω and 15kΩ as discussed previously.
In addition a 0.1μF ceramic bypass capacitor is placed on
the INTVCC pin.
Layout Considerations
To achieve accurate current sensing, a Kelvin connection
is required. The minimum trace width for 1oz copper
foil is 0.02" per amp to make sure the trace stays at a
reasonable temperature. Using 0.03" per amp or wider
is recommended. Note that 1oz copper exhibits a sheet
resistance of about 530μΩ. Small resistances add up
quickly in high current applications. To improve noise
immunity, put the resistive dividers to the UV, OV and FB
pins close to the device and keep traces to VDD and GND
short. It is also important to put the bypass capacitor for
the INTVCC pin, C3, as close as possible between INTVCC
and GND. 0.1μF capacitors from the UV pins (and OV pins
through resistor R2) to GND also helps reject supply noise.
Figure 5 shows a layout that addresses these issues. Note
that surge suppressor, Z1 is placed between supply and
ground using wide traces.
Digital Interface
The LTC4222 communicates with a bus master using a
2-wire interface compatible with I2C Bus and SMBus, an
I2C extension for low power devices. The LTC4222 is a
read-write slave device and supports SMBus bus Read
Byte, Write Byte, Read Word and Write Word commands.
A complete list of the resistors of the LTC4222 is shown
in Table 2. The second word in a Read Word command is
the contents of the subsequent 8-bit register. The second
word in a Write Word command is ignored. Data formats
for these commands are shown in Figures 6 to 11.
The LTC4222 interface also features a 25ms timeout feature
to prevent the bus being stuck low if a communication
error occurs. If either the SCL or SDA lines remain low
for more than 25ms the LTC4222 will reset it’s interface
and release the SDAO pin, freeing the bus to resume
communication.
The LTC4222 also features PMBus compatibility, the in-
terface will not acknowledge unsupported commands and
the internal addresses are in the manufacturer specied
address space under the PMBus specication.
START and STOP Conditions
When the bus is idle, both SCL and SDA are high. A bus
master signals the beginning of a transmission with a start
condition by transitioning SDA from high to low while SCL
is high, as shown in Figure 6. When the master has nished
communicating with the slave, it issues a STOP condition
by transitioning SDA from low to high while SCL is high.
The bus is then free for another transmission.
I2C Device Addressing
Twenty seven distinct bus addresses are available using
three 3-state address pins, ADR0, ADR1 and ADR2. Table 1
shows the correspondence between pin states and ad-
dresses. In addition, the LTC4222 responds to two special
addresses. Address (1100 0110) is a mass write address
that writes to all LTC4222s, regardless of their individual
address settings. Mass write can be disabled by setting
register bit 4 in the CONTROL register of channel 2 to zero.
Address (0001 100) is the SMBus Alert Response Address.
If the LTC4222 is pulling low on the ALERT pin due to an
Figure 5. Recommended Layout
SS
CONFIG
INTVCC
GND
OV
UV
V
DD
SENSE
+
SENSE
–
LTC4222UHD
4222 F05
VIAS TO
GROUND
PLANE
VIA TO
GROUND
PLANE
SENSE RESISTOR RS
ILOAD
CSS
C3
R2
R3
CF
Z1
R1
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相关代理商/技术参数 |
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| LTC4222IG#TRPBF | 功能描述:IC CTRLR DUAL HOT SWAP 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4222IG-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Hot Swap Controller with I2C Compatible Monitoring |
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| LTC4222IUH#PBF | 功能描述:IC CTRLR DUAL HOT SWAP 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
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