參數(shù)資料
型號： TPS54040DGQ
廠商： TEXAS INSTRUMENTS INC
元件分類： 穩(wěn)壓器
英文描述： 0.5 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO10
封裝： PLASTIC, MSOP-10
文件頁數(shù)： 14/47頁
文件大小： 2435K
代理商： TPS54040DGQ
Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
RT kOhm
sw kHz 1.0888
206033
(
) =
(
)
(11)
0
100
200
300
400
500
200
300
400
500
600
700
800
900
1000
1100
RT/CLK-Resistance-kW
f
-SwitchingFrequency-kHz
s
1200
V =12V,
T =25°C
I
J
0
500
1000
1500
2000
2500
0
25
50
75
100
125
150
175
200
f
-SwitchingFrequency-kHz
s
RT/CLK-ClockResistance-kW
V =12V,
T =25°C
I
J
Overcurrent Protection and Frequency Shift
www.ti.com................................................................................................................................................................................................... SLVS918 – MARCH 2009
DETAILED DESCRIPTION (continued)
The switching frequency of the TPS54040 is adjustable over a wide range from approximately 100kHz to
2500kHz by placing a resistor on the RT/CLK pin. The RT/CLK pin voltage is typically 0.5V and must have a
resistor to ground to set the switching frequency. To determine the timing resistance for a given switching
frequency, use Equation 11 or the curves in Figure 39 or Figure 40. To reduce the solution size one would
typically set the switching frequency as high as possible, but tradeoffs of the supply efficiency, maximum input
voltage and minimum controllable on time should be considered.
The minimum controllable on time is typically 130ns and limits the maximum operating input voltage.
The maximum switching frequency is also limited by the frequency shift circuit. More discussion on the details of
the maximum switching frequency is located below.
SWITCHING FREQUENCY
vs
RT/CLK RESISTANCE HIGH FREQUENCY RANGE
RT/CLK RESISTANCE LOW FREQUENCY RANGE
Figure 39. High Range RT
Figure 40. Low Range RT
The TPS54040 implements current mode control which uses the COMP pin voltage to turn off the high side
MOSFET on a cycle by cycle basis. Each cycle the switch current and COMP pin voltage are compared, when
the peak switch current intersects the COMP voltage, the high side switch is turned off. During overcurrent
conditions that pull the output voltage low, the error amplifier will respond by driving the COMP pin high,
increasing the switch current. The error amplifier output is clamped internally, which functions as a switch current
limit.
To increase the maximum operating switching frequency at high input voltages the TPS54040 implements a
frequency shift. The switching frequency is divided by 8, 4, 2, and 1 as the voltage ramps from 0 to 0.8 volts on
VSENSE pin.
The device implements a digital frequency shift to enable synchronizing to an external clock during normal
startup and fault conditions. Since the device can only divide the switching frequency by 8, there is a maximum
input voltage limit in which the device operates and still have frequency shift protection.
During short-circuit events (particularly with high input voltage applications), the control loop has a finite minimum
controllable on time and the output has a low voltage. During the switch on time, the inductor current ramps to
the peak current limit because of the high input voltage and minimum on time. During the switch off time, the
inductor would normally not have enough off time and output voltage for the inductor to ramp down by the ramp
up amount. The frequency shift effectively increases the off time allowing the current to ramp down.
Copyright 2009, Texas Instruments Incorporated
21
Product Folder Link(s): TPS54040
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TPS54040DGQ 制造商:Texas Instruments 功能描述:Power Management IC 制造商:Texas Instruments 功能描述:IC, STEP-DOWN CONVERTER, MSOP-10
TPS54040DGQR 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 3.5V-42Vin,0.5A Step Down SWIFT Convrtr RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
TPS54040EVM-456 功能描述:電源管理IC開發(fā)工具 0.5A,12-42V In SWIFT Cnvrtr Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
TPS54040EVM-456 制造商:Texas Instruments 功能描述:EVALUATION MODULE FOR TPS54040 SWIFT(TM)
TPS54040-Q1 制造商:TI 制造商全稱:Texas Instruments 功能描述:0.5-A 42-V STEP-DOWN SWIFTa?￠ DC/DC CONVERTER WITH Eco-modea?￠
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