HIT HA1835P Datasheet
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
Pin Arrangement
R
C
P-RUN
Rf
Cf
Vout
GND
1
R
2
R
3
4
5
6
7
14
13
12
11
10
RES
RES
CS
V
CC
V
CONT
Comp *
9
Vadj
8
(Top View)
Note: HA1848P: 9 pin is non connection.
Pin Functions
Pin No. Symbol Functions
1R
2C
R
R
3 P-RUN Clock pulse input terminal for watchdog timer
4 Rf Frequency band width of filter circuit depends on resistance connected to Rf
5 Cf Frequency band width of filter circuit depends on capacitance connected to Cf
6 Vout Connect to external PNP transistor's collector: This pin supplies 5 V regulated
7 GND Ground
8 Vadj Output voltage fine tuning terminal
9 Comp Phase compensation terminal: Connect less than 100 pF capacitor between V
10 V
11 V
CONT
CC
12 CS Connect current sense resistor, which protects the external PNP transistor,
13 RES * Reset pulse output terminal for low level reset type microcomputer
14 RES * Reset pulse output terminal for high level reset type microcomputer
Note: RES and RES are open-collector output terminals, so connect a pull-up resistor of about 5 kΩ.
Reset pulse width depends on resistance connected to R
R
Recommended range: 100 kΩ to 1 MΩ
Reset pulse width depends on capacitance connected to C
R
Recommended range: 100 kΩ to 500 kΩ
voltage for internal circuit
and Comp. HA1848P is non connection
External PNP transistor's base control terminal
Supply voltage terminal: Operating supply voltage range is 6 V to 30 V
between V
and CS
CC
CC
2
Block Diagram
V
CC
C
1
Reference
Voltage
11
R
V
CC
Current
Limiter
CS
12
Error
Amp
CS
Q
10
V
CONT
HA1835P/HA1848P
Vout
Vout HA1835P
6
5 kΩ
2 kΩ
9 Comp *
8 Vadj
14 RES
Fail Detector
3P-RUN
(Band Pass Filter)
4 5
Rf
300 kΩCf0.01 µF
Power on Reset Detector
Reset Signal Oscillator
1 27
R
R
560 kΩ
GND
Note: HA1848P: 9 pin is non connection.
C
R
0.1 µF
13 RES
3
HA1835P/HA1848P
Absolute Maximum Ratings (Ta = 25°C)
Item Symbol Rating Unit
Supply voltage V
P-RUN input voltage V
Output voltage V
Output current I
Control terminal voltage V
Control terminal current I
CC
P-RUN
RES
V
RES
RES
I
RES
CONT
CONT
Power dissipation (Note) PT * 400 mW
Operating temperature range Topr –40 to +85 °C
Storage temperature range Tstg –50 to +125 °C
Soldering temperature Tsol +260 (< 10 sec) °C
Note: Ta ≤ 77°C. If Ta > 77°C, derate by 8.3 mW/°C.
30 V
–0.3 to Vout V
17.5 V
17.5 V
2mA
2mA
V
CC
V
20 mA
4
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