參數(shù)資料
型號: PTH04040WAH
廠商: TEXAS INSTRUMENTS INC
元件分類: 電源模塊
英文描述: 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
封裝: DIP-20
文件頁數(shù): 5/25頁
文件大?。?/td> 535K
代理商: PTH04040WAH
THD
R
=
12.9
V
2.63
THD
k
= 2.191
1
+
0.283
V
HYS
THD
R
PTH04040W
2
4
6
1
3 5
VI
7
8
UVLOProg
Inhibit
GND
RTHD
C
1,000 F
I
m
www.ti.com
SLTS238C – SEPTEMBER 2005 – REVISED JUNE 2010
ADJUSTING THE UNDERVOLTAGE LOCKOUT (UVLO) OF THE PTH04040W
The PTH04040W power modules incorporate an input undervoltage lockout (UVLO). The UVLO feature prevents
the operation of the module until there is sufficient input voltage to produce a valid output voltage. This enables
the module to provide a monotonic powerup for the load circuit, and also limits the magnitude of current drawn
from the module’s input source during the power-up sequence.
The UVLO characteristic is defined by the on-threshold (VTHD) and hysterisis (VHYS) voltages. Below the on
threshold, the Inhibit control is overriden, and the module does not produce an output. Hysterisis voltage is the
difference between the on and off threshold voltages. It ensures a clean power-up, even when the input voltage
is rising slowly. The hysterisis prevents start-up oscillations, which can occur if the input voltage droops slightly
when the module begins drawing current from the input source.
UVLO ADJUSTMENT
The UVLO feature of the PTH04040W gives the user the option of adjusting the on-threshold voltage higher than
the default value. This might be desirable if the module is powered from a 5-V input bus. This prevents the
module from operating until the input bus has risen closer to its regulation voltage.
The adjustment method uses the UVLO Prog control (pin 8). If the UVLO Prog pin is left open circuit, the
onthreshold voltage remains at its nominal value of 2.63 V (see electrical specification table). This ensures that
the unadjusted module produces a regulated output when the minimum input voltage is applied. The hysterisis
voltage is approximately 0.62 V, which correlates to an off-threshold voltage of about 2 V. The magnitude of the
hysterisis is automatically set to about 22% of the onthreshold. So if the on-threshold voltage is increased, then
the Hysterisis also increases.
UVLO ADJUSTMENT METHOD
Figure 10 shows the placement of the resistor, RTHD, for adjusting the UVLO on-threshold voltage. It connects
from the UVLO Prog control pin to GND. Equation 2 determines the value of RTHD required to adjust VTHD to a
new value. The default value is 2.63 V, and it can only be adjusted higher. Once the value of RTHD has been set,
Equation 3 is used to determine the new hysterisis voltage.
(2)
(3)
Figure 10. UVLO Program Resistor Placement
Copyright 2005–2010, Texas Instruments Incorporated
13
Product Folder Link(s): PTH04040W
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PTH04040WAS 功能描述:DC/DC轉(zhuǎn)換器 60A 3.3/5V-In Wide Output Adj Pwr Mdl RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓(標(biāo)稱): 輸出端數(shù)量:1 輸出電壓(通道 1):3.3 V 輸出電流(通道 1):600 mA 輸出電壓(通道 2): 輸出電流(通道 2): 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸:
PTH04040WAST 功能描述:DC/DC轉(zhuǎn)換器 2.95-5.5Vin 0.8-3.6V 60A RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓(標(biāo)稱): 輸出端數(shù)量:1 輸出電壓(通道 1):3.3 V 輸出電流(通道 1):600 mA 輸出電壓(通道 2): 輸出電流(通道 2): 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸:
PTH04040WAZ 功能描述:DC/DC轉(zhuǎn)換器 60A 3.3/5V-In Wide Output Adj Pwr Mdl RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓(標(biāo)稱): 輸出端數(shù)量:1 輸出電壓(通道 1):3.3 V 輸出電流(通道 1):600 mA 輸出電壓(通道 2): 輸出電流(通道 2): 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸:
PTH04040WAZT 功能描述:DC/DC轉(zhuǎn)換器 2.95-5.5Vin 0.8-3.6V 2.045" x1.045"x0.357 RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓(標(biāo)稱): 輸出端數(shù)量:1 輸出電壓(通道 1):3.3 V 輸出電流(通道 1):600 mA 輸出電壓(通道 2): 輸出電流(通道 2): 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸:
PTH04070W 制造商:TI 制造商全稱:Texas Instruments 功能描述:3-A, 3.3/5-V INPUT ADJUSTABLE SWITCHING REGULATOR