전자부품 데이터시트 검색엔진 |
|
74HC4538 데이터시트(PDF) 8 Page - Hitachi Semiconductor |
|
74HC4538 데이터시트(HTML) 8 Page - Hitachi Semiconductor |
8 / 16 page HD74HC4538 8 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), turning on transistor M1. Thus C X is allowed to quickly charge up to VCC (23) to await the next trigger signal. Retrigger Operation When used in the retriggerable mode (Fig. 3), the HC4538 may be retriggered during timing out of the output pulse at any time after the trigger-control circuit flip-flopw 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 (Switching Waveform 1) is a function of internal propagation delays and the discharge time of C X: Fig. 4 shows the device configured in the non-retriggerable mode. Power-Down Considerations Large values of C X may cause problems when powering down the HC4538 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•CX/(30 mA). For example, if V CC = 5 V and CX = 15 µF, the VCC supply must turn off no faster than t = (5 V)•(15 µF)/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 voltage occurs, the HC4538 may sustain damage. To avoid this possibility, use an external clamping diode. |
유사한 부품 번호 - 74HC4538 |
|
유사한 설명 - 74HC4538 |
|
|
링크 URL |
개인정보취급방침 |
ALLDATASHEET.CO.KR |
ALLDATASHEET 가 귀하에 도움이 되셨나요? [ DONATE ] |
Alldatasheet는? | 광고문의 | 운영자에게 연락하기 | 개인정보취급방침 | 링크교환 | 제조사별 검색 All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |