System Reset PST623 MITSUMI System Reset Monolithic IC PST623 Outline This low reset type IC functions in CPU and other logic systems to detect input voltage and reset the system accurately when power is turned on or interruped. Features 1. 2. 3. 4. 5. 6. 7. Detection voltage can be set easily (2 external resistors) High percision voltage detection Internal reference voltage Enables high voltage check (at stage before Reg) Low operating limit voltage High output current during ON Low current consumption Built-in delay circuit (1 external capacitor) 1.25±2% 0.65V typ. 10mA min. 40µA typ. Applications 1. Reset circuits in microcomputers, CPUs and MPUs 2. Logic circuit reset circuits 3. Level detection circuits Package VSOP-8A (PST623XS) SIP-5A (PST623XW) Pin Assignment 8 1 7 2 6 3 VSOP-8A 5 4 1 VS 2 NC 3 TC 4 GND 5 RESET 6 NC 7 NC 8 VCC 1 2 3 SIP-5A 4 5 1 VCC 2 VS 3 TC 4 GND 5 RESET System Reset PST623 MITSUMI Absolute Maximum Ratings (Ta=25°C) Item Storage temperature Maximum power supply voltage Allowable power consumption Input pin voltage Symbol TSTG VCC max. Pd max. VID Rating -40~+125 10 300 -0.3~VCC Units °C V mW V Rating 2.0~10.0 -25~+75 Units V °C Recommended Operating Conditions Item Power supply voltage Operating temperature Electrical Characteristics Symbol VCCOP TOPG (Except where noted otherwise, VCC=5V, Ta=25°C) Item Detection reference voltage Hysteresis voltage Detection reference voltage temperature coefficient L level output voltage Output leakage current Circuit current while on Circuit current while off "H" transport delay time "L" transport delay time Symbol VS VS Measurement conditions RL=470Ω, VIN=H L RL=470Ω, VIN=L H L Vs T RL=470Ω, Ta=-25~+75°C ±0.01 VOL IOH ICCL ICCH tpLH tpHL 0.3 Operation limit voltage VOPL Output current while on Delay time setting comparator Threshold level Capacitor charging current Vs input current IOL VIN=1.0V, RL=470Ω VIN=1.5V, VOUT=10V VIN=1.0V, RL=∞ VIN=1.5V, RL=∞ RL=4.7kΩ, Cd=0.047uF RL=4.7kΩ, Cd=0.047uF RL=4.7kΩ, VOL =< 0.4V Minimum power supply voltage for which output can maintain Lo. VIN=1.0V, RL=0 Vtsh ITC IIN RL=470Ω, VTC=L VIN=1.5V, VTC=0.2V VIN=1.35V Equivalent Circuit Diagram VSOP-8A H SIP-5A Min. Typ. Max. Units 1.225 1.25 1.275 V 12 25 50 mV 50 42 110 15 0.65 %/°C 0.45 ±0.1 90 70 V µA µA µA mS µS 0.85 V 10 mA 1.25 1.4 1.55 V 0.39 0.60 40 0.81 µA nA System Reset PST623 MITSUMI Notes on Using PST623 1. Input voltage rise and fall VS+0.4V VS VS-0.4V 30µS Be sure to give an incline of more than 30µS to rise and fall for input with varied power supply voltage (VCC) and bleeder resistance. Also, when setting input bleeder resistance, VS pin input current is affected and the detection voltage setting will differ from the set value if current on the bleeder resistor is too low. Use input bleeder resistor R2 at 250kΩ or less. 2. Delay time setting H transmission delay time can be set easily as follows from the TC pin, using the external capacitor. T = Cd (2.33 106) [S] Use the external capacitor at 1µF (approx. 2.33S) or less. Characteristics Current consumption for OFF 70 65 60 55 50 45 40 35 30 25 20 15 Detection voltage (V) ICC (µA) Detection voltage 0 1 2 3 4 5 6 7 8 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 -30 9 10 VCC (V) H transport delay time (S) 101 100 10-1 10-2 10-3 10-4 10-3 10 30 50 H transport delay time (S) H transport delay time 10-4 10-5 -10 10-2 Capacitance (µF) 10-1 100 70 System Reset PST623 MITSUMI Application Circuits 1. Circuit Diagram 2. Detection Voltage Setting R1+R2 VS ·=· 1.25 · —————— R2 * Note The value of I2 should be sufficient to ignore I3. Make I2 > 5µA. R2 < 250kΩ 3. How to widen hysteresis Voltage VIN1 so that Q1 ON goes OFF. (R1+R2) R1//R2 VIN1=————————— [1.25 (V) · (R3+R1//R2+R4//R5) - ———— (R4 · VBE+R5 · VCC)] R2 · (R3+R4//R5) R4+R5 Voltage VIN2 so that Q1 OFF goes ON. (R1+R2) VIN2=————— [1.275 (V) · (R1//R2+R3) -VOL · (R1//R2)] R2 · R3 VOL: Low level output voltage VBE: Base-emitter voltage of transistor Q1 R1//R2 R1 · R2 ———— R1+R2 R4//R5 R4 · R5 ———— R4+R5