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參數(shù)資料
| 型號： | PT8125A |
| 英文描述： | SMPS Controller |
| 中文描述： | 開關電源控制器 |
| 文件頁數(shù)： | 9/10頁 |
| 文件大?。?/td> | 182K |
| 代理商： | PT8125A |
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
Using the On/Off Standby Function of the
PT8120 Series of Programmable ISRs
The PT8120 series of programmable ISRs incorporates
an On/Off Standby function. This feature may be used
to turn the regulated output of the module off while input
voltage is applied. This places the module in “standby”
mode. The standby control may be used for power-up
sequencing, or wherever there is a requirement to control
the module’s output status from another circuit.
The Standby function is provided by the STBY* control,
pin 6. If pin 6 is left open-circuit the regulator operates
normally, providing a regulated output when a valid sup-
ply voltage is applied to Vin (pins 10-16) with respect to
GND (pins 17-22). Connecting pin 6 to ground 1 places
the regulator in standby mode 2, and reduces the input
current to typically 35mA. Applying a ground signal to
pin 6 prior to power-up, will inhibit the output during
the period that input power is applied. When the ground
signal to pin 6 is removed, the regulator initiates a soft-
start to re-establish the set output voltage. 3 To ensure
that the regulator output is properly enabled, the STBY*
control pin must be open circuit.
Table 1 Standby Control Requirements 2
Parameter
Min
Typ
Max
VIH
—
Open Cct. 1
VIL
–0.2V
—
0.8V
ISTBY
–0.5mA
Notes:
1. The standby on a PT8120 series regulators must be
controlled with an open-collector (or open-drain)
transistor (See fig. 1). Do Not use a pull-up resistor.
Table 1 gives the STBY* pin parameters. The control
pin has an open-circuit voltage of 5Vdc. To shut the
regulator output off, the control pin must be “pulled” to
less than 0.8Vdc with a low-impedance sink to ground.
Figure 1
Figure 2
PT8120 Series & PT8139
2. In the standby mode the output of the regulator is tri-
state, and the output voltage falls at the rate that the
load circuit discharges the output filter capacitors.
3. When the ground signal to the Standby pin is
removed, the regulator output initiates a soft-start
cycle by first asserting a low impedance to ground. If
an external voltage is applied to the output bus, it will
sink current and possibly over-stress the part.
Turn-On Time
Turning Q1 in Figure 1 off, removes the low-voltage
signal at pin 6. After approximately 5-ms the regulator
output rises and reaches full regulation within 40ms.
Fig. 2 shows the typical waveforms of a PT8121 following
the prompt turn-off of Q1. The turn-off of Q1 corresponds
to the rise in Vstby. The output voltage was set to 3.3V,
and the waveforms were measured with a 12V input source,
and 18A resistive load.
L
O
A
D
C
OUT
+
C
IN
+
V
IN
V
O =3.3V
GND
V
O SENSE
1 =Off
L
in
1H
GND
PT8121
4321
31
23–30
617–22
12–16
5
11
VID4 – VID0
Sense
V
IN
V
OUT
STBY
GND
VID
Common
Q1
BSS138
Vo (1V/Div)
Iin (5A/Div)
Vstby (5V/Div)
HORIZ SCALE: 5ms/Div
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| PT8125C | 功能描述:DC/DC轉換器 4.5-7.6V 28A 12V In Multiphase Prog ISR 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）: 安裝風格:SMD/SMT 封裝 / 箱體尺寸: |
| PT8125N | 功能描述:開關變換器、穩(wěn)壓器與控制器 4.5-7.6V 28A 12V In Multiphase Prog ISR RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| PT812BB | 功能描述:CBL ASSY PIGTAIL 12' BNCM BNCM RoHS:是 類別:電纜組件 >> 同軸，RF 系列:* 標準包裝:1 系列:* |
| PT812NB | 功能描述:CBL ASSY PIGTAIL 12' NM BNCM RoHS:是 類別:電纜組件 >> 同軸，RF 系列:* 標準包裝:1 系列:* |
| PT812NN | 功能描述:CBL ASSY PIGTAIL 12' NM NM RoHS:是 類別:電纜組件 >> 同軸，RF 系列:* 標準包裝:1 系列:* |
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