参数资料
型号: PTH08T255WAD
厂商: TEXAS INSTRUMENTS INC
元件分类: 电源模块
英文描述: DC-DC REG PWR SUPPLY MODULE
封装: PLASTIC, MODULE-22
文件页数: 16/34页
文件大小: 4336K
代理商: PTH08T255WAD
ADJUSTING THE UNDERVOLTAGE LOCKOUT (UVLO)
UVLO
THD
250
R
(k
)
V
7.3
=
W
-
(4)
V
I
GND
PTH08T255W
6
7
8
9
12
13
GND
C
I
+
UDG-08151
14
15
V
I
V
I
V
I
GND
V
I
21
Inhibit/UVLO
R
UVLO
www.ti.com ........................................................................................................................................................................................... SLTS290 – NOVEMBER 2008
The PTH08T255W 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 clean, monotonic powerup for the load circuit, and also limits the magnitude of
current drawn from the regulator’s input source during the power-up sequence.
The UVLO characteristic is defined by the ON threshold (VTHD) voltage. Below the ON threshold, the Inhibit
control is overridden, and the module does not produce an output. The hysteresis voltage, which is the difference
between the ON and OFF threshold voltages, is set at 500 mV. The hysteresis prevents start-up oscillations,
which can occur if the input voltage droops slightly when the module begins drawing current from the input
source.
The UVLO feature of the PTH08T255W module allows for limited adjustment of the ON threshold voltage. The
adjustment is made via the Inhbit/UVLO Prog control pin (pin 11) using a single resistor (see Figure 18). When
pin 11 is left open circuit, the ON threshold voltage is internally set to its default value, which is 7.2 volts. The ON
threshold might need to be raised if the module is powered from a tightly regulated 12-V bus. Adjusting the
threshold prevents the module from operating if the input bus fails to completely rise to its specified regulation
voltage.
Equation 4 determines the value of RUVLO required to adjust VTHD to a new value. The default value is 7.2 V, and
it may only be adjusted to a higher value.
Table 6 lists the standard resistor values for RUVLO for different values of the on-threshold (VTHD) voltage.
Table 6. Standard RUVLO values for Various VTHD values
VTHD (V)
8.0
8.5
9.0
9.5
10.0
10.5
11.0
RUVLO (kΩ)
357
210
147
113
93.1
78.7
68.1
Figure 18. Undervoltage Lockout Adjustment Resistor Placement
Copyright 2008, Texas Instruments Incorporated
23
Product Folder Link(s): PTH08T255W
相关PDF资料
PDF描述
PTH08T261WAD 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
PTH08T260WAST 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
PTH08T261WAST 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
PTH08T260WAD 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
PTH08T260WAZ 1-OUTPUT DC-DC REG PWR SUPPLY MODULE
相关代理商/技术参数
参数描述
PTH08T255WAS 功能描述:DC/DC转换器 40A,8-14V In,3-5.25V Out,Non-Iso Pwr Mod RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压(标称): 输出端数量:1 输出电压(通道 1):3.3 V 输出电流(通道 1):600 mA 输出电压(通道 2): 输出电流(通道 2): 安装风格:SMD/SMT 封装 / 箱体尺寸:
PTH08T255WAST 功能描述:DC/DC转换器 40A,8-14V In,3-5.25V Out,Non-Iso Pwr Mod RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压(标称): 输出端数量:1 输出电压(通道 1):3.3 V 输出电流(通道 1):600 mA 输出电压(通道 2): 输出电流(通道 2): 安装风格:SMD/SMT 封装 / 箱体尺寸:
PTH08T255WAZ 功能描述:DC/DC转换器 40A,8-14V In,3-5.25V Out,Non-Iso Pwr Mod RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压(标称): 输出端数量:1 输出电压(通道 1):3.3 V 输出电流(通道 1):600 mA 输出电压(通道 2): 输出电流(通道 2): 安装风格:SMD/SMT 封装 / 箱体尺寸:
PTH08T255WAZT 功能描述:DC/DC转换器 40A,8-14V In,3-5.25V Out,Non-Iso Pwr Mod RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压(标称): 输出端数量:1 输出电压(通道 1):3.3 V 输出电流(通道 1):600 mA 输出电压(通道 2): 输出电流(通道 2): 安装风格:SMD/SMT 封装 / 箱体尺寸:
PTH08T260W 制造商:TI 制造商全称:Texas Instruments 功能描述:3-A, 4.5-V to 14-V INPUT, NON-ISOLATED, WIDE-OUTPUT, ADJUSTABLE POWER MODULE WITH TurboTrans