- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377982 > MM74HC4538SJ (FAIRCHILD SEMICONDUCTOR CORP) 1.5A, 260kHz Low Voltage Buck Regulator with External Bias Capability; Package: SOIC-8 Narrow Body; No of Pins: 8; Container: Rail; Qty per Container: 98 PDF資料下載
參數(shù)資料
| 型號： | MM74HC4538SJ |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 諧振器 |
| 英文描述： | 1.5A, 260kHz Low Voltage Buck Regulator with External Bias Capability; Package: SOIC-8 Narrow Body; No of Pins: 8; Container: Rail; Qty per Container: 98 |
| 中文描述： | HC/UH SERIES, DUAL MONOSTABLE MULTIVIBRATOR, PDSO16 |
| 封裝： | 5.30 MM, EIAJ TYPE2, SOP-16 |
| 文件頁數(shù)： | 4/10頁 |
| 文件大小： | 119K |
| 代理商： | MM74HC4538SJ |
www.fairchildsemi.com
4
M
Circuit Operation
(Continued)
toggle, taking the Q output of the HC4538 to a LOW State
(#19), and completing the time-out cycle.
RESET OPERATION
A low voltage applied to the Reset pin always forces the Q
output of the HC4538 to a LOW State.
The timing diagram illustrates the case in which reset
occurs (#20) while C
X
is charging up toward the reference
voltage of the upper reference circuit (#21). When a reset
occurs, the output of the reset latch goes LOW (#22), turn-
ing ON transistor M1. Thus C
X
is allowed to quickly charge
up to V
CC
(#23) to await the next trigger signal.
Recovery time is the required delay after reset goes inac-
tive to a new trigger rising edge. On the diagram it is shown
as (#26) to (#27).
RETRIGGER OPERATION
In the retriggerable mode, the HC4538 may be retriggered
during timing out of the output pulse at any time after the
trigger-control circuit flip-flop has been reset (#24).
Because the trigger-control circuit flip-flop resets shortly
after C
X
has discharged to the reference voltage of the
lower reference circuit (#25), the minimum retrigger time, t
rr
is a function of internal propagation delays and the dis-
charge time of C
X
:
at room temperature
POWER-DOWN CONSIDERATIONS
Large values of C
X
may cause problems when powering
down the MM74HC4538 because of the amount of energy
stored in the capacitor. When a system containing this
device is powered down, the capacitor may discharge from
V
CC
through the input protection diodes at pin 2 or pin 14.
Current through the protection diodes must be limited to 30
mA; therefore, the turn-off time of the V
CC
power supply
must not be faster than t
=
V
CC
C
X
/(30 mA). For example, if
V
CC
=
5V and C
X
=
15
μ
F, the V
CC
supply must turn OFF
no faster than t
=
(15V)
(15
μ
F)/30 mA
=
2.5 ms. This is
usually not a problem because power supplies are heavily
filtered and cannot discharge at this rate.
When a more rapid decrease of V
CC
to zero volts occurs,
the MM74HC4538 may sustain damage. To avoid this pos-
sibility, use an external clamping diode, D
X
, connected
from V
CC
to the C
X
pin.
SET UP RECOMMENDATIONS
Minimum
R
X
=
1 k
Minimum
C
X
=
0 pF.
相關PDF資料 |
PDF描述 |
|---|---|
| MM74HC540WM | Inverting Octal 3-STATE Buffer Octal 3-STATE Buffer |
| MM74HC541WM | Inverting Octal 3-STATE Buffer Octal 3-STATE Buffer |
| MM74HC540SJ | Inverting Octal 3-STATE Buffer Octal 3-STATE Buffer |
| MM74HC540 | 1.5A, 260kHz Low Voltage Buck Regulator with External Bias Capability; Package: SOIC-8 Narrow Body; No of Pins: 8; Container: Tape and Reel; Qty per Container: 2500 |
| MM74HC540MTC | 1.5 A, 260 kHz Low Voltage Buck Regulators with External Bias; Package: DFN18 6x5, 0.5p; No of Pins: 18; Container: Tape and Reel; Qty per Container: 2500 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MM74HC4538SJ_Q | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| MM74HC4538SJX | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| MM74HC51J | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Dual AND-OR-Invert Gate / Dual AND-OR Gate |
| MM74HC51N | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Dual AND-OR-Invert Gate / Dual AND-OR Gate |
| MM74HC533 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:TRI-STATE-R Octal D-Type Latch with Inverted Outputs |
發(fā)布緊急采購，3分鐘左右您將得到回復。