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 1 14 RES CR 2 13 RES P-RUN 3 12 CS Rf 4 11 VCC Cf 5 10 VCONT Vout 6 9 Comp * GND 7 8 Vadj (Top View) Note: HA1848P: 9 pin is non connection. Pin Functions Pin No. Symbol Functions 1 RR Reset pulse width depends on resistance connected to RR Recommended range: 100 kΩ to 1 MΩ 2 CR Reset pulse width depends on capacitance connected to CR 3 P-RUN Clock pulse input terminal for watchdog timer 4 Rf Frequency band width of filter circuit depends on resistance connected to Rf Recommended range: 100 kΩ to 500 kΩ 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 voltage for internal circuit 7 GND Ground 8 Vadj Output voltage fine tuning terminal 9 Comp Phase compensation terminal: Connect less than 100 pF capacitor between V CC and Comp. HA1848P is non connection 10 VCONT External PNP transistor's base control terminal 11 VCC Supply voltage terminal: Operating supply voltage range is 6 V to 30 V 12 CS Connect current sense resistor, which protects the external PNP transistor, between V CC and CS 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. 2 HA1835P/HA1848P Block Diagram RCS VCC Vout Q C1 11 VCC 12 CS 10 VCONT Current Limiter Reference Voltage 6 Vout HA1835P 5 kΩ Error Amp 9 Comp * 8 Vadj 2 kΩ 14 RES Fail Detector (Band Pass Filter) P-RUN 3 7 4 Power on Reset Detector Reset Signal Oscillator 5 Rf 300 kΩ 1 Cf 0.01 µF 13 RES 2 RR 560 kΩ CR 0.1 µF GND Note: HA1848P: 9 pin is non connection. 3 HA1835P/HA1848P Absolute Maximum Ratings (Ta = 25°C) Item Symbol Rating Unit Supply voltage VCC 30 V P-RUN input voltage VP-RUN –0.3 to Vout V Output voltage VRES 17.5 V VRES 17.5 V I RES 2 mA I RES 2 mA Control terminal voltage VCONT VCC V Control terminal current I CONT 20 mA 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 Output current Note: Ta ≤ 77°C. If Ta > 77°C, derate by 8.3 mW/°C. 4 HA1835P/HA1848P Electrical Characteristics (VCC = 12 V, Vout = 5 V, Ta = 25°C) Item Symbol Min Typ Max Unit Test Conditions Power supply terminal current ICC — 6.3 12 mA VCC = 17.5 V (No load), with PNP transistor Regulator Vout1 4.75 5.00 5.25 V VCC = 6 to 17.5 V, Iout = 0.5 A Vout2 4.70 5.00 5.30 V VCC = 6 to 17.5 V, Iout = 1 A Line regulation δVOline –50 — +50 mV VCC = 6 to 17.5 V, Iout = 1 A Load regulation δVOload –100 — +100 mV Iout = 10 mA to 0.5 A Ripple rejection RREJ 40 75 — dB ei = 0.5 Vrms, fi = 1 kHz Limiter operating current ICS 1.0 — 2.0 A RSC = 0.2 Ω Output voltage temperature coefficient δVout/δT — –0.6 — mV/°C P-RUN input Low-level input voltage VIL — — 0.8 V section High-level input voltage VIH 2.0 — — V Low-level input current IIL –120 –60 — µA VIL = 0 V High-level input current IIH — 1.8 3.0 mA Vout = 5 V, VIH = 5 V VOL1 — — 0.4 V IOL = 2 mA Reset terminal IOH1 — — 5.0 µA VOH = 5 V leakage current IOH3 — — 30 µA VOH = 17.5 V Power on time ton 80 130 200 ms Rf = 300 kΩ, RR = 560 kΩ, Clock off reset time toff 60 130 220 ms Cf = 0.01 µF, CR = 0.1 µF Reset pulse low-level time tRL 40 80 160 ms Reset pulse high-level time tRH 50 100 200 ms Output voltage section Reset circuit Reset terminal low-level section voltage Reset time 5 HA1835P/HA1848P Test Circuit 2SB857D S2 3 P-RUN 12 CS RSC 10 VCONT Vout 6 0.2 Ω 5 kΩ RES 14 11 VCC S1 HA1835P RES 13 VBatt Rf 4 Cf 5 300 kΩ 6 5 kΩ GND 7 0.01 µF RR 1 Vadj 8 CR 2 560 kΩ 0.1 µF Counter + C2 − 100 µF 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 R (Vadj − GND) ≈ 7.14 Vout − 5 (kΩ) (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 HA1835P/HA1848P Application Circuit Example Q 2SB857D RSC VBatt VReg 0.2 Ω + C1 − 10 µF 11 VCC + C2 − 100 µF 12 CS 10 VCONT 5 kΩ 6 Vout RES 13 RES VCC Microcomputer system P-RUN 3 Rf 4 Cf 5 Rf 300 kΩ GND 7 Cf 0.01 µF RR 1 CR 2 RR 560 kΩ CR 0.1 µF System burst VCC P-RUN toff tRL RES ton Power-on reset signal 8 tRH Reset output signal 3 Hz I/O port HA1835P/HA1848P Characteristic Curves Output voltage VOUT (V) 5 4 Ta = 25°C 3 IOUT = 0.1 A 2 0.5 A 1.0 A 1 0 0 5 10 Input voltage VIN (V) Figure 1 Output Voltage vs. Input Voltage Output voltage VOUT (V) 6 Ta = 25°C 4 R = 0.5 Ω 0.2 Ω 2 0 0 1 2 Output current IOUT (A) Figure 2 Output Voltage vs. Output Current 5.1 Output voltage VOUT (V) VIN = 12 V IOUT = 1 A 5.0 4.9 −50 0 50 100 Ambient temperature Ta (°C) Figure 3 Output Voltage vs. Ambient Temperature 9 10 µF 200 CR µF .1 =0 C R = 0. 22 VIN = 12 V Ta = 25°C 7µ F 100 CR 0 50 k = 4 0.0 100 k 1M 200 k 500 k Resistor RR (Ω) Figure 4 Automatic Reset Pulse High Time vs. Resistor 200 VIN = 12 V Ta = 25°C 2µ CR F .2 =0 100 .1 µF CR = 0 100 k 200 k 500 k Resistor RR (Ω) Figure 5 Automatic Reset Pulse Low Time vs. Resistor 0. = CR 0. = 1M µF R VIN = 12 V Ta = 25°C 1 22 100 7µ F 50 CR 0 50 k 47 µF C R = 0.0 µF 0 50 k C Power-on reset time ton (ms) Automatic reset pulse low time tRL (ms) Automatic reset pulse high time tRH (ms) HA1835P/HA1848P 100 k = 200 k 500 k Resistor RR (Ω) Figure 6 Power-on Reset Time vs. Resistor 4 0.0 1M HA1835P/HA1848P 5k Ta = 25°C VIN = 12 V 1k 500 Allowable operation clock pulse duty cycle 200 A B 100 Duty = B A+B 50 30 40 60 80 100 Clock pulse duty cycle (%) Figure 7 Clock Pulse Frequency vs. Clock Pulse Duty Cycle 0 20 20 k Ta = 25°C VIN = 12 V Duty = 50% 10 k Clock pulse frequency f (Hz) Clock pulse frequency f (Hz) 2k System run-away sense region 5k 2k 1k 500 Normal operation region 200 100 50 System run-away sense region 20 100 k 200 k Resistor Rf (Ω) 500 k Figure 8 Clock Pulse Frequency vs. Resistor 11 HA1835P/HA1848P Package Dimensions Unit: mm 19.20 20.32 Max 8 6.30 7.40 Max 14 1.30 7 2.54 ± 0.25 0.48 ± 0.10 0.51 Min 2.39 Max 2.54 Min 5.06 Max 1 7.62 + 0.10 0.25 – 0.05 0° – 15° Hitachi Code JEDEC EIAJ Mass (reference value) 12 DP-14 Conforms Conforms 0.97 g 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. 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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. 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