MB3771_06

FUJITSU SEMICONDUCTOR DATA SHEET DS04-27400-11E ASSP For power supply applications BIPOLAR Power Supply Monitor MB3771 ■ DESCRIPTION The Fujitsu MB3771 is designed to monitor the voltage level of one or two power supplies (+5 V and an arbitrary voltage) in a microprocessor circuit, memory board in large-size computer, for example. If the circuit’s power supply deviates more than a specified amount, then the MB3771 generates a reset signal to the microprocessor. Thus, the computer data is protected from accidental erasure. Using the MB3771 requires few external components. To monitor only a +5 V supply, the MB3771 requires the connection of one external capacitor. The level of an arbitrary detection voltage is determined by two external resistors. The MB3771 is available in an 8-pin Dual In-Line, Single In-Line Package or space saving Flat Package. ■ FEATURES • • • • • • • • • • Precision voltage detection (VSA = 4.2 V ± 2.5 %) User selectable threshold level with hysteresis (VSB = 1.23 V ± 1.5 %) Monitors the voltage of one or two power supplies (5 V and an arbitrary voltage, >1.23 V) Usable as over voltage detector Low voltage output for reset signal (VCC = 0.8 V Typ) Minimal number of external components (one capacitor Min) Low power dissipation (ICC = 0.35 mA Typ, VCC = 5 V) Detection threshold voltage has hysteresis function Reference voltage is connectable. One type of package (SOP-8pin : 1 type) ■ APPLICATION • Industrial Equipment • Arcade Amusement etc. Copyright©2003-2006 FUJITSU LIMITED All rights reserved MB3771 ■ PIN ASSIGNMENT (TOP VIEW) CT VSC OUTC GND 1 2 3 4 8 7 6 5 RESET VSA VSB /RESIN VCC (FPT-8P-M01) ■ BLOCK DIAGRAM VCC 5 ≅ 1.24 V ≅ 1.24 V ≅ 100 kΩ VSA 7 ≅ 40 kΩ + − Comp. A + REFERENCE VOLTAGE + − R Q ≅ 12 µA ≅ 10 µA 2 VSC − + − Comp. C + VSB / RESIN 6 − Comp. B S 4 1 CT 8 3 GND RESET OUTC 2 MB3771 ■ FUNCTIONAL DESCRIPTIONS Comparators Comp.A and Comp.B apply a hysteresis to the detected voltage, so that when the voltage at either the VSA or VSB pin falls below 1.23 V the RESET output signal goes to “low” level. Comp. B may be used to detect any given voltage(APPLICATION CIRCUIT 3 : Arbitrary Voltage Supply Monitor), and can also be used as a forced reset pin (with reset hold time) with TTL input (APPLICATION CIRCUIT 6 : 5V Power Supply Monitor with forced RESET input (VCC = 5 V) ). Note that if Comp.B is not used, the VSB pin should be connected to the VCC pin (APPLICATION CIRCUIT 1 : 5V Power Supply Monitor). Instantaneous breaks or drops in the power supply can be detected as abnormal conditions by the MB3771 within a 2 µs interval. However because momentary breaks or drops of this duration do not cause problems in actual systems in some cases, a delayed trigger function can be created by connecting capacitors to the VSA or VSB pin (APPLICATION CIRCUIT 8 : Supply Voltage Monitoring with Delayed Trigger). Because the RESET output has built-in pull-up resistance, there is no need to connect to external pull-up resistance when connected to a high impedance load such as a CMOS logic IC. Comparator Comp. C is an open-collector output comparator without hysteresis, in which the polarity of input/ output characteristics is reversed. Thus Comp. C is useful for over-voltage detection (APPLICATION CIRCUIT 11 : Low Voltage and Over Voltage Detection (VCC = 5 V) ) and positive logic RESET signal output (APPLICATION CIRCUIT 7 : 5 V Power Supply Monitor with Non-inverted RESET), as well as for creating a reference voltage (APPLICATION CIRCUIT 10 : Reference Voltage Generation and Voltage Sagging Detection). Note that if Comp. C is not used, the VSC pin should be connected to the GND pin (APPLICATION CIRCUIT 1 : 5V Power Supply Monitor). ■ FUNCTION EXPLANATION VHYS VS VCC VCC CT 1 2 3 4 8 7 6 5 RESET 0.8 V t TPO TPO RESET t (1) (2) (3) (4) (5) (6) (7) (8) (1) When VCC rises to about 0.8V, RESET goes low. (2) When VCC reaches VS +VHYS, CT then begins charging. RESET remains low during this time (3) RESET goes high when CT begins charging. : TPO = CT × 10 5 (Refer to “CT pin capacitance vs. reset hold time” in “TYPICAL CHARACTERISTICS”.) (4) When VCC level drops lower then VS, then RESET goes low and CT starts discharging. (5) When VCC level reaches VS + VHYS, then CT starts charging. In the case of voltage sagging, if the period from the time VCC goes lower than or equal to VS to the time VCC reaches VS +VHYS again, is longer than tPI, (as specified in the AC Characteristics), CT is discharged and charged successively. (6) After TPO passes, and VCC level exceeds VS + VHYS, then RESET goes high. (7) Same as Point 4. (8) RESET remains low until VCC drops below 0.8V. 3 MB3771 ■ ABSOLUTE MAXIMUM RATINGS Parameter Power supply voltage Symbol VCC VSA Input voltage VSB VSC Power dissipation Storage temperature PD Tstg Rating Min −0.3 −0.3 −0.3 −0.3 ⎯ −55 Max +20 VCC + 0.3 ( < +20) +20 +20 200 (Ta ≤ 85 °C) +125 Unit V V V V mW °C WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. ■ RECOMMENDED OPERATING CONDITIONS Parameter Power supply voltage Output current Operating ambient temperature Symbol VCC IRESET IOUTC Ta Value Min 3.5 0 0 −40 Max 18 20 6 +85 Unit V mA mA °C WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device’s electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within their recommended operating condition ranges. Operation outside these ranges may adversely affect reliability and could result in device failure. No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representatives beforehand. 4 MB3771 ■ ELECTRICAL CHARACTERISTICS 1. DC Characteristics (VCC = 5 V, Ta = + 25 °C) Parameter Power supply current Symbol ICC1 ICC2 VSAL (DOWN) Detection voltage VSAH (UP) Hysteresis width Detection voltage Deviation of detection voltage Hysteresis width Input current VHYSA VSB ∆VSB VHYSB IIHB IILB VOHR Output voltage Output sink current CT charge current Input current Detection voltage Deviation of detection voltage Output leakage current Output voltage Output sink current Reset operation minimum supply voltage VOLR IRESET ICT IIHC IILC VSC ∆VSC IOHC VOLC IOUTC VCCL VSB = 5 V VSB = 0 V IRESET = −5 µA, VSB = 5 V IRESET = 3mA, VSB = 0 V IRESET = 10mA, VSB = 0 V VOLR = 1.0 V, VSB = 0 V VSB = 5 V, VCT = 0.5 V VSC = 5 V VSC = 0 V ⎯ Ta = −40 °C to +85 °C VCC = 3.5 V to 18 V VOHC = 18 V IOUTC = 4 mA, VSC = 5 V VOLC = 1.0 V, VSC = 5 V VOLR = 0.4 V, IRESET = 200 µA VSB Ta = −40 °C to +85 °C VCC = 3.5 V to 18 V ⎯ Conditions VSB = 5 V, VSC = 0 V VSB = 0 V, VSC = 0 V VCC Ta = −40 °C to +85 °C VCC Ta = −40 °C to +85 °C ⎯ Value Min ⎯ ⎯ 4.10 4.05 4.20 4.15 50 1.212 1.200 ⎯ 14 ⎯ ⎯ 4.5 ⎯ ⎯ 20 9 ⎯ ⎯ 1.225 1.205 ⎯ ⎯ ⎯ 6 ⎯ Typ 350 400 4.20 4.20 4.30 4.30 100 1.230 1.230 3 28 0 20 4.9 0.28 0.38 40 12 0 50 1.245 1.245 3 0 0.15 15 0.8 Max 500 600 4.30 4.35 4.40 4.45 150 1.248 1.260 10 42 250 250 ⎯ 0.4 0.5 ⎯ 16 500 500 1.265 1.285 10 1 0.4 ⎯ 1.2 Unit µA µA V V V V mV V V mV mV nA nA V V V mA µA nA nA V V mV µA V mA V 5 MB3771 2. AC Characteristics Parameter Symbol tPI tPO tr tf t* PD 1 Conditions ⎯ ⎯ RL = 2.2 kΩ, CL = 100 pF ⎯ RL = 2.2 kΩ, CL = 100 pF (VCC = 5 V, Ta = + 25 °C, CT = 0.01 µF) Value Unit Min Typ Max 5.0 0.5 ⎯ ⎯ ⎯ ⎯ ⎯ ⎯ 1.0 1.0 0.1 2 0.5 1.0 ⎯ 1.5 1.5 0.5 10 ⎯ ⎯ µs ms µs µs µs µs µs VSA, VSB input pulse width Reset hold time RESET rise time RESET fall time Propagation delay time tPHL*2 tPLH*2 *1: In case of VSB termination. *2: In case of VSC termination. 6 MB3771 ■ APPLICATION CIRCUIT 1. 5V Power Supply Monitor Monitored by VSA. Detection threshold voltage is VSAL and VSAH VCC MB3771 1 CT 2 3 4 8 7 6 5 RESET Logic circuit 2. 5V Power Supply Voltage Monitor (Externally Fine-Tuned Type) The VSA detection voltage can be adjusted externally. Resistance R1 and R2 are set sufficiently lower than the IC internal partial voltage resistance, so that the detection voltage can be set using the ratio between resistance R1 and R2. (Refer to the table below). • R1, R2 calculation formula (when R1