參數(shù)資料
型號(hào): TPS40004
廠商: Texas Instruments, Inc.
英文描述: "Low Input (2.25V-5.5V) 300 kHz Frequency
中文描述: 低輸入 (2.25V-5.5V) 300 kHz 頻率同步降壓控制器,具有輸出驅(qū)動(dòng)/吸入
文件頁數(shù): 5/20頁
文件大?。?/td> 280K
代理商: TPS40004
TPS40000, TPS40001
TPS40002, TPS40003
TPS40004, TPS40005
SLUS507B JANUARY 2002 REVISED AUGUST 2003
13
www.ti.com
APPLICATION INFORMATION
setting the current limit
Connecting a resistor from VDD to ILIM sets the current limit. A 15-
A current sink internal to the device causes
a voltage drop at ILIM that is equal to the overcurrent threshold voltage. Ensure that (VDD0.8 V) ≤ VILIM ≤ VDD.
The tolerance of the current sink is too loose to do an accurate current limit. The main purpose is for hard fault
protection of the power switches. Given the tolerance of the ILIM sink current, and the RDS(on) range for a
MOSFET, it is generally possible to apply a load that thermally damages the converter. This device is intended
for embedded converters where load characteristics are defined and can be controlled.
soft-start and shutdown
These two functions are common to the SS/SD pin. The voltage at this pin is the controlling voltage of the error
amplifier during startup. This reduces the transient current required to charge the output capacitor at startup,
and allows for a smooth startup with no overshoot of the output voltage if done properly. A shutdown feature
can be implemented as shown in Figure 5.
CSS
UDG01143
SS/SD
4
TPS40000
SHUTDOWN
3
A
Figure 5. Shutdown Implementation
The device shuts down when the voltage at the SS/SD pin falls below 120 mV. Because of this limitation, it is
recommended that a MOSFET be used as the controlling device, as in Figure 5. An open-drain CMOS logic
output would work equally well.
rectifier zero-current
Both the TPS40000 and TPS40002 parts are source-only, thus preventing reverse current in the synchronous
rectifier. Synchronous rectification is terminated by sensing the voltage, SW with respect to ground, across the
low-side MOSFET. When SW node is greater than 7 mV, rectification is terminated and stays off until the next
PWM cycle. In order to filter out undesired noise on the SW node, the zero-current comparator is blanked for
75 ns from the time the rectifier is turned on.
The TPS40001 and TPS40003 parts enable the zero-current comparator, (and therefore prevent reverse
current), while soft-start is active. However, when the output reaches regulation; that is, at the end of the
soft-start time, this comparator is disabled to allow the synchronous rectifier to sink current.
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TPS40004DGQ 功能描述:電壓模式 PWM 控制器 Lo Input 300kHz Freq Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
TPS40004DGQG4 功能描述:電壓模式 PWM 控制器 Lo Input 300kHz Freq Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
TPS40004DGQR 功能描述:電壓模式 PWM 控制器 Lo Input 300kHz Freq Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
TPS40004DGQRG4 功能描述:電壓模式 PWM 控制器 Lo Input 300kHz Freq Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
TPS40005 制造商:TI 制造商全稱:Texas Instruments 功能描述:LOW-INPUT VOLTAGE-MODE SYNCHRONOUS BUCK CONTROLLER