參數(shù)資料
型號(hào)： TPS54331DG4
廠商： TEXAS INSTRUMENTS INC
元件分類： 穩(wěn)壓器
英文描述： 2 A SWITCHING REGULATOR, 684 kHz SWITCHING FREQ-MAX, PDSO8
封裝： GREEN, PLASTIC, MS-012AA, SOIC-8
文件頁(yè)數(shù)： 26/27頁(yè)
文件大?。?/td> 794K
代理商： TPS54331DG4
EN
1.25V
VIN
+
-
Ren1
Ren2
TPS54331
1
A
m
3
A
m
START
STOP
V
- V
Ren1 =
3
A
m
EN
START
EN
V
Ren2 =
V
- V
+ 1
A
Ren1
m
(
)
( )
(
)
SS
ref
SS
C
nF
V
T
ms
=
I
A
m
SLVS839C – JULY 2008 – REVISED MARCH 2010
www.ti.com
ENABLE AND ADJUSTABLE INPUT UNDER-VOLTAGE LOCKOUT (VIN UVLO)
The EN pin has an internal pull-up current source that provides the default condition of the TPS54331 operating
when the EN pin floats.
The TPS54331 is disabled when the VIN pin voltage falls below internal VIN UVLO threshold. It is recommended
to use an external VIN UVLO to add Hysteresis unless VIN is greater than (VOUT + 2 V). To adjust the VIN UVLO
with Hysteresis, use the external circuitry connected to the EN pin as shown in Figure 12. Once the EN pin
voltage exceeds 1.25 V, an additional 3 mA of hysteresis is added. Use Equation 1 and Equation 2 to calculate
the resistor values needed for the desired VIN UVLO threshold voltages. The VSTART is the input start threshold
voltage, the VSTOP is the input stop threshold voltage and the VEN is the enable threshold voltage of 1.25 V. The
VSTOP should always be greater than 3.5 V.
Figure 12. Adjustable Input Undervoltage Lockout
(1)
(2)
PROGRAMMABLE SLOW START USING SS PIN
It is highly recommended to program the slow start time externally because no slow start time is implemented
internally. The TPS54331 effectively uses the lower voltage of the internal voltage reference or the SS pin
voltage as the power supply’s reference voltage fed into the error amplifier and will regulate the output
accordingly. A capacitor (CSS) on the SS pin to ground implements a slow start time. The TPS54331 has an
internal pull-up current source of 2mA that charges the external slow start capacitor. The equation for the slow
start time (10% to 90%) is shown in Equation 3 . The Vref is 0.8 V and the ISS current is 2 mA.
(3)
The slow start time should be set between 1ms to 10 ms to ensure good start-up behavior. The slow start
capacitor should be no more than 27nF.
If during normal operation, the input voltage drops below the VIN UVLO threshold, or the EN pin is pulled below
1.25 V, or a thermal shutdown event occurs, the TPS54331 stops switching.
ERROR AMPLIFIER
The TPS54331 has a transconductance amplifier for the error amplifier. The error amplifier compares the
VSENSE voltage to the internal effective voltage reference presented at the input of the error amplifier. The
transconductance of the error amplifier is 92 mA/V during normal operation. Frequency compensation
components are connected between the COMP pin and ground.
SLOPE COMPENSATION
In order to prevent the sub-harmonic oscillations when operating the device at duty cycles greater than 50%, the
TPS54331 adds a built-in slope compensation which is a compensating ramp to the switch current signal.
8
Copyright 2008–2010, Texas Instruments Incorporated
Product Folder Link(s): TPS54331
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TPS54331DR 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 3A 28V In Step Down SWIFT DC/DC Cnvrtr RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
TPS54331DRG4 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 26V,3A DC-DC Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
TPS54331DR-P 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述:
TPS54331EVM-232 功能描述:電源管理IC開(kāi)發(fā)工具 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(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
TPS54331EVM-232 制造商:Texas Instruments 功能描述:DEVELOPMENT TOOL
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