参数资料
型号: UCC28250PW
厂商: Texas Instruments
文件页数: 22/53页
文件大小: 0K
描述: IC REG CTRLR PWM CM/VM 20-TSSOP
标准包装: 70
PWM 型: 电流/电压模式
输出数: 1
频率 - 最大: 1MHz
占空比: 100%
电源电压: 4.7 V ~ 17 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 125°C
封装/外壳: 20-TSSOP(0.173",4.40mm 宽)
包装: 管件
其它名称: 296-27776-5
UCC28250PW-ND
SLUSA29C – APRIL 2010 – REVISED JULY 2011
ILIM (Current Limit for Cycle-By-Cycle Over-Current Protection) (17/4)
Cycle-by-cycle current limit is accomplished using the ILIM pin for current mode control or for voltage mode
control. The input to the ILIM pin represents the primary current information. If the voltage sensed at ILIM pin
exceeds 0.5 V, the current sense comparator terminates the pulse of output OUTA or OUTB. If the high current
condition persists, the controller operates in a cycle-by-cycle current limit mode with duty cycle determined by the
current sense comparator instead of the PWM comparator. ILIM pin is pulled down by an internal switch at the
rising edge of every clock cycle. This internal switch remains on for an additional 70 ns after OUTA or OUTB
goes high to blank leading edge transient noise in the current sensing loop. This reduces the filtering
requirements at the ILIM pin and improves the current sense response time.
Transformer Primary
Side Current
UCC28250
ILIM
CT
1:n
R S
C S
C HICC
HICC
Figure 15. Current Limit Circuit
Once the over current protection level I PK is selected, the current transformer turns ratio and the burden resistor
value can be decided as:
R S =
0.5 V ′ n
I PK
(11)
In this equation, current transformer turns ratio is 1:n and R S is the burden resistor value.
Some filtering capacitance is required to reduce the sensing noise. Choose the RC constant at about 100 ns,
and calculate the capacitor value as:
C S =
100ns
R S
(12)
The cycle-by-cycle current limit operation time before all four outputs shut down can be programmed by external
capacitor C HICC at HICC pin. (See HICC pin description)
22
Product Folder Link(s): UCC28250
Copyright ? 2010 – 2011, Texas Instruments Incorporated
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UCC28250PWT 制造商:TI 制造商全称:Texas Instruments 功能描述:Advanced PWM Controller With Pre-Bias Operation
UCC28250RGPR 功能描述:电压模式 PWM 控制器 Adv PWM Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel
UCC28250RGPT 功能描述:电压模式 PWM 控制器 Adv PWM Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel