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부품번호 | HA1848P 기능 |
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기능 | Watchdog Timer | ||
제조업체 | Hitachi Semiconductor | ||
로고 | |||
전체 13 페이지수
HA1835P/HA1848P
Watchdog Timer
Description
The HA1835P and HA1848P is a monolithic voltage regulator control designed for microcomputer
systems. In addition to the voltage regulator, it include watchdog timer function and power-on reset
function.
These ICs can perform many function in various microcomputer systems with few external parts.
Features
• Regulated power supply control function
Wide area of operational voltage; VCC = 6 V to 30 V
Available external PNP-type transistor, suited to any system power supply
Built-in overcurrent limiter for external PNP-type transistor
Output voltage can be adjusted exactry in the range from 4 V to 6 V
• Watchdog timer
Internal bandpass filter control circuit (pulse width detect type) and reset signal oscillator
Fail-safe utility
Bandpass filter characteristics can be set by external resister (Rf) and capacitance (Cf)
• Automatic reset
Automatic power-on reset
Pulse generator characteristics can be set by external resistor (RR) and capacitance (CR)
Alternative between RES and RES output
HA1835P/HA1848P
Absolute Maximum Ratings (Ta = 25°C)
Item
Symbol
Rating
Supply voltage
P-RUN input voltage
Output voltage
Output current
Control terminal voltage
Control terminal current
Power dissipation (Note)
Operating temperature range
VCC
VP-RUN
VRES
VRES
I RES
I RES
VCONT
I CONT
PT *
Topr
30
–0.3 to Vout
17.5
17.5
2
2
VCC
20
400
–40 to +85
Storage temperature range
Tstg
–50 to +125
Soldering temperature
Tsol
+260 (< 10 sec)
Note: Ta ≤ 77°C. If Ta > 77°C, derate by 8.3 mW/°C.
Unit
V
V
V
V
mA
mA
V
mA
mW
°C
°C
°C
4
4페이지 HA1835P/HA1848P
Functional Description
Voltage Regulator
The HA1835P, and HA1848P supplies 5 V regulated output from a wide VCC input range (VCC = 6 V to
17.5 V). The external PNP transistor should be selected according to the supply current demand of the
system. Connect a more than 100 µF capacitor between Vout and GND to realize the 5 V regulated output.
The resistor connected from the Vadj terminal to the Vout or GND terminal fine tunes the output voltage.
A resistor between Vadj and the Vout decreases the output voltage, and a resistor between Vadj and GND
increases the output voltage.
R (Vout − Vadj) ≈
5 ⋅ Vout − 7.14
5 − Vout
(kΩ)
R (Vadj − GND) ≈
7.14
Vout − 5
(kΩ)
Current Limiter
To protect the external transistor from overcurrent, connect a current-sense resistor between the CS
terminal and the VCC terminal. The value of this resistor should be:
RSC ≈
0.3 V
Iout (Limit)
(at Ta = 25°C)
Power-On Reset
The HA1835P, and HA1848P can output a reset pulse to start the microcomputer at power on (figure 6).
The external resistor RR and capacitor CR determine the power-on reset timing.
Note that RES and RES are open-collector terminals. They should therefore be connected to a pull-up
resistor of about 5 kΩ.
Watchdog Timer
The watchdog timer is a fail-safe function. It can reset the microcomputer system if the system runs out of
control. It does this be monitoring a pulse output by the system's software. It uses a bandpass filter to
determine whether the pulse frequency is within the system's normal frequency band (figure 7, 8). External
resistor and capacitor Rf and Cf determine the frequency range of the bandpass filter. If the pulse
frequency is not within the frequency band, the HA1835P, and HA1848P outputs a reset pulse.
7
7페이지 | |||
구 성 | 총 13 페이지수 | ||
다운로드 | [ HA1848P.PDF 데이터시트 ] |
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구매 문의 | 일반 IC 문의 : 샘플 및 소량 구매 ----------------------------------------------------------------------- IGBT, TR 모듈, SCR 및 다이오드 모듈을 포함한 광범위한 전력 반도체를 판매합니다. 전력 반도체 전문업체 상호 : 아이지 인터내셔날 사이트 방문 : [ 홈페이지 ] [ 블로그 1 ] [ 블로그 2 ] |
부품번호 | 상세설명 및 기능 | 제조사 |
HA1848P | Watchdog Timer | Hitachi Semiconductor |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |