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参数资料
| 型号： | PTH04040WAST |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 电源模块 |
| 英文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 封装： | ROHS COMPLIANT, DIP-20 |
| 文件页数： | 21/22页 |
| 文件大小： | 747K |
| 代理商： | PTH04040WAST |
For technical support and more information, see inside back cover or visit www.ti.com
Notes
Adjusting the Under-Voltage Lockout (UVLO) of the
PTH04040W Power Modules
The PTH04040W power modules incorporate an input
under-voltage lockout (UVLO). The UVLO feature
prevents the operation of the module until there is suffi-
cient 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
(V
THD) and hysterisis (VHYS) voltages. Below the ‘on’
threshold, the Inhibit control is overriden, and the mod-
ule will not produce an output. The hysterisis voltage is
the difference between the ‘on’ and ‘off’ threshold volt-
ages. It ensures a clean power-up, even when the input
voltage is rising slowly. Hysterisis prevents start-up os-
cillations, 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 would
prevent 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 on-
threshold voltage remains at its nominal value of 2.63 V
(see electrical specification table). This ensures that the
unadjusted module will produce 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 on-
threshold. So if the on-threshold voltage is increased,
then the hystersis will also increase slightly.
CI
1,000 F
PTH04040W
2
4
6
13
5
VI
7
8
UVLO Prog
Inhibit
GND
VI
GND
RTHD
Figure 2–2; UVLO Program Resistor Placement
Adjustment Method
Figure 2-2 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 2-2
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 Eq. 2-3 may be used to determine
the new hystersis voltage.
PTH04040W
= 2.191
1
+ 0.283
V
HYS
THD
R
THD
R
=
12.9
V
– 2.63
THD
k
Eq. 2–2
Eq. 2–3
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| PTH04040WAZ | 功能描述:DC/DC转换器 60A 3.3/5V-In Wide Output Adj Pwr Mdl 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: |
| PTH04040WAZT | 功能描述:DC/DC转换器 2.95-5.5Vin 0.8-3.6V 2.045" x1.045"x0.357 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: |
| PTH04070W | 制造商:TI 制造商全称:Texas Instruments 功能描述:3-A, 3.3/5-V INPUT ADJUSTABLE SWITCHING REGULATOR |
| PTH04070W_07 | 制造商:TI 制造商全称:Texas Instruments 功能描述:3-A, 3.3/5-V INPUT ADJUSTABLE SWITCHING REGULATOR |
| PTH04070WAD | 功能描述:DC/DC转换器 3-A 3.3/5-V Input Adj Swtch Regulator 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: |
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