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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; V CC = 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
RR CR P-RUN Rf Cf Vout GND 1 2 3 4 5 6 7 14 13 12 11 10 9 8 RES RES CS VCC VCONT Comp * Vadj
(Top View) Note: HA1848P: 9 pin is non connection.
Pin Functions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Symbol RR CR P-RUN Rf Cf Vout GND Vadj Comp VCONT VCC CS RES * RES * Functions Reset pulse width depends on resistance connected to RR Recommended range: 100 k to 1 M Reset pulse width depends on capacitance connected to CR Clock pulse input terminal for watchdog timer Frequency band width of filter circuit depends on resistance connected to Rf Recommended range: 100 k to 500 k Frequency band width of filter circuit depends on capacitance connected to Cf Connect to external PNP transistor's collector: This pin supplies 5 V regulated voltage for internal circuit Ground Output voltage fine tuning terminal Phase compensation terminal: Connect less than 100 pF capacitor between V CC 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 Connect current sense resistor, which protects the external PNP transistor, between V CC and CS Reset pulse output terminal for low level reset type microcomputer 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 k.
2
HA1835P/HA1848P
Block Diagram
VCC C1 11 VCC Current Limiter Reference Voltage 12 CS 10 VCONT 6 Vout HA1835P RCS Q Vout
5 k
Error Amp
9 Comp * 8 Vadj 2 k 14 RES
P-RUN 3
Fail Detector (Band Pass Filter)
Power on Reset Detector Reset Signal Oscillator
13 RES
7
4 Rf 300 k
5 Cf 0.01 F
1 RR 560 k
2 CR 0.1 F
GND Note: HA1848P: 9 pin is non connection.
3
HA1835P/HA1848P
Absolute Maximum Ratings (Ta = 25C)
Item Supply voltage P-RUN input voltage Output voltage Symbol VCC VP-RUN VRES VRES Output current I RES I RES Control terminal voltage Control terminal current Power dissipation (Note) Operating temperature range Storage temperature range Soldering temperature VCONT I CONT PT * Topr Tstg Tsol Rating 30 -0.3 to Vout 17.5 17.5 2 2 VCC 20 400 -40 to +85 -50 to +125 +260 (< 10 sec) Unit V V V V mA mA V mA mW C C C
Note: Ta 77C. If Ta > 77C, derate by 8.3 mW/C.
4
HA1835P/HA1848P
Electrical Characteristics (VCC = 12 V, Vout = 5 V, Ta = 25C)
Item Power supply terminal current Regulator section Line regulation Load regulation Ripple rejection Limiter operating current Output voltage temperature coefficient P-RUN input Low-level input voltage section High-level input voltage Low-level input current High-level input current Reset circuit Reset terminal low-level section voltage Reset terminal leakage current Reset time Power on time Clock off reset time Reset pulse low-level time Reset pulse high-level time Output voltage Symbol ICC Vout1 Vout2 VOline VOload RREJ ICS Vout/T VIL VIH IIL IIH VOL1 IOH1 IOH3 ton toff tRL tRH Min -- 4.75 4.70 -50 -100 40 1.0 -- -- 2.0 -120 -- -- -- -- 80 60 40 50 Typ 6.3 5.00 5.00 -- -- 75 -- -0.6 -- -- -60 1.8 -- -- -- 130 130 80 100 Max 12 5.25 5.30 +50 +100 -- 2.0 -- 0.8 -- -- 3.0 0.4 5.0 30 200 220 160 200 Unit mA V V mV mV dB A mV/C V V A mA V A A ms ms ms ms VIL = 0 V Vout = 5 V, VIH = 5 V IOL = 2 mA VOH = 5 V VOH = 17.5 V Rf = 300 k, RR = 560 k, Cf = 0.01 F, CR = 0.1 F Test Conditions VCC = 17.5 V (No load), with PNP transistor VCC = 6 to 17.5 V, Iout = 0.5 A VCC = 6 to 17.5 V, Iout = 1 A VCC = 6 to 17.5 V, Iout = 1 A Iout = 10 mA to 0.5 A ei = 0.5 Vrms, fi = 1 kHz RSC = 0.2
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HA1835P/HA1848P
Test Circuit
2SB857D S2
3 P-RUN 12 CS RSC S1 VBatt Rf 4 300 k Cf 5 0.2 11 VCC
10 VCONT
Vout 6 5 k RES 14 5 k
+ C2 - 100 F
HA1835P
RES 13 Vadj 8 CR 2 560 k 0.1 F
GND 7 0.01 F
RR 1
Counter
6
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 F 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) R (Vadj - GND) 5 Vout - 7.14 5 - Vout 7.14 Vout - 5 (k) (k)
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 = 25C)
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 k. 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
HA1835P/HA1848P
Application Circuit Example
RSC
+ C1 - 10 F
VBatt
Q 2SB857D
0.2 11 VCC 12 CS 10 VCONT 6 Vout RES 13 5 k VCC
+ C2 - 100 F
VReg
RES
Microcomputer system P-RUN 3 Rf 4 Rf 300 k Cf 5 GND 7 Cf 0.01 F RR 1 RR 560 k CR 2 CR 0.1 F I/O port
System burst VCC
P-RUN toff tRL ton Power-on reset signal tRH Reset output signal 3 Hz
RES
8
HA1835P/HA1848P
Characteristic Curves
5
Output voltage VOUT (V)
4 Ta = 25C 3 IOUT = 0.1 A 0.5 A 1.0 A 1
2
0
0
5
10
Input voltage VIN (V) Figure 1 Output Voltage vs. Input Voltage
6
Output voltage VOUT (V)
Ta = 25C 4 R = 0.5 2
0.2
0
0
1
2
Output current IOUT (A) Figure 2 Output Voltage vs. Output Current
5.1
VIN = 12 V
Output voltage VOUT (V)
IOUT = 1 A
5.0
4.9 -50
0
50
100
Ambient temperature Ta (C) Figure 3 Output Voltage vs. Ambient Temperature
9
HA1835P/HA1848P
Automatic reset pulse high time tRH (ms)
F
200
=
VIN = 12 V Ta = 25C
C
0.
CR
.1 =0
F
R
22
100
CR
0 50 k
=
4 0.0
7
F
200 k 500 k Resistor RR () Figure 4 Automatic Reset Pulse High Time vs. Resistor
100 k
1M
Automatic reset pulse low time tRL (ms)
200 VIN = 12 V Ta = 25C
CR .2 =0 2 F
100
CR = 0
0 50 k 100 k
.1 F
47 F
C R = 0.0
200 k 500 k Resistor RR () Figure 5 Automatic Reset Pulse Low Time vs. Resistor
1M
Power-on reset time ton (ms)
100 VIN = 12 V Ta = 25C 50
F
22
0.
CR
=
0.
1
F
C
R
=
CR
0 50 k
=
4 0.0
7
F
200 k 500 k Resistor RR () Figure 6 Power-on Reset Time vs. Resistor
100 k
1M
10
HA1835P/HA1848P
5k Ta = 25C VIN = 12 V 2k
Clock pulse frequency f (Hz)
1k
500
Allowable operation clock pulse duty cycle
200 AB 100 Duty = 50 30 B A+B
40 60 80 100 Clock pulse duty cycle (%) Figure 7 Clock Pulse Frequency vs. Clock Pulse Duty Cycle
0
20
20 k 10 k
Ta = 25C VIN = 12 V Duty = 50%
Clock pulse frequency f (Hz)
5k
System run-away sense region
2k 1k 500
Normal operation region
200 100 50
System run-away sense region
20 100 k 200 k Resistor Rf () 500 k
Figure 8 Clock Pulse Frequency vs. Resistor
11
HA1835P/HA1848P
Package Dimensions
Unit: mm
19.20 20.32 Max 14 8 6.30 7.40 Max 1
2.39 Max
1.30
7 7.62
0.51 Min
2.54 Min 5.06 Max
2.54 0.25
0.48 0.10
0.25 - 0.05 0 - 15
+ 0.10
Hitachi Code JEDEC EIAJ Mass (reference value)
DP-14 Conforms Conforms 0.97 g
12
HA1835P/HA1848P
Cautions
1. Hitachi neither warrants nor grants licenses of any rights of Hitachi's or any third party's patent, copyright, trademark, or other intellectual property rights for information contained in this document. Hitachi bears no responsibility for problems that may arise with third party's rights, including intellectual property rights, in connection with use of the information contained in this document. 2. Products and product specifications may be subject to change without notice. Confirm that you have received the latest product standards or specifications before final design, purchase or use. 3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However, contact Hitachi's sales office before using the product in an application that demands especially high quality and reliability or where its failure or malfunction may directly threaten human life or cause risk of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation, traffic, safety equipment or medical equipment for life support. 4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly for maximum rating, operating supply voltage range, heat radiation characteristics, installation conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable failure rates or failure modes in semiconductor devices and employ systemic measures such as failsafes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other consequential damage due to operation of the Hitachi product. 5. This product is not designed to be radiation resistant. 6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without written approval from Hitachi. 7. Contact Hitachi's sales office for any questions regarding this document or Hitachi semiconductor products.
Hitachi, Ltd.
Semiconductor & Integrated Circuits. Nippon Bldg., 2-6-2, Ohte-machi, Chiyoda-ku, Tokyo 100-0004, Japan Tel: Tokyo (03) 3270-2111 Fax: (03) 3270-5109
URL
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Hitachi Semiconductor (America) Inc. 179 East Tasman Drive, San Jose,CA 95134 Tel: <1> (408) 433-1990 Fax: <1>(408) 433-0223 Hitachi Europe GmbH Electronic components Group Dornacher Strae 3 D-85622 Feldkirchen, Munich Germany Tel: <49> (89) 9 9180-0 Fax: <49> (89) 9 29 30 00 Hitachi Europe Ltd. Electronic Components Group. Whitebrook Park Lower Cookham Road Maidenhead Berkshire SL6 8YA, United Kingdom Tel: <44> (1628) 585000 Fax: <44> (1628) 778322 Hitachi Asia Pte. Ltd. 16 Collyer Quay #20-00 Hitachi Tower Singapore 049318 Tel: 535-2100 Fax: 535-1533 Hitachi Asia Ltd. Taipei Branch Office 3F, Hung Kuo Building. No.167, Tun-Hwa North Road, Taipei (105) Tel: <886> (2) 2718-3666 Fax: <886> (2) 2718-8180 Hitachi Asia (Hong Kong) Ltd. Group III (Electronic Components) 7/F., North Tower, World Finance Centre, Harbour City, Canton Road, Tsim Sha Tsui, Kowloon, Hong Kong Tel: <852> (2) 735 9218 Fax: <852> (2) 730 0281 Telex: 40815 HITEC HX
Copyright ' Hitachi, Ltd., 1998. All rights reserved. Printed in Japan.
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