YB1921 3-Pin Microprocessor Reset Monitor Features Introduction The YB1921 is a cost-effective system supervisor Integrated Circuit (IC) designed to monitor VCC in digital and mixed signal systems and provide a warning signal when the system power supply is out of working range, and a reset signal to the host processor when necessary. No external components are required. z Precision VCC Monitor for 2.8V, 3.0V, 3.3V, and 5.0V Supplies z 140msec Guaranteed Minimum RESET Output Duration z RESET Output Guaranteed to VCC=1.0V z Low 18μA Supply Current The reset output is driven active within 20μsec z VCC Transient Immunity of VCC falling through the reset voltage threshold. Reset is maintained active for a minimum of 140msec after VCC rises above the reset threshold. The YB1921 has an active-low RESET output. The output of the YB1921 is guaranteed valid down to VCC=1V. z Small SOT-23 Package z No External Components z Wide Operating Temperature: 0°C to 85°C The YB1921 is optimized to reject fast transient glitches on the VCC line. Low supply current of 18μA (VCC=3.3V) makes these devices suitable for battery powered applications. Applications z Computers z Embedded systems z Battery powered equipment z Critical µP power supply monitoring Application Diagram YB1921 www.yobon.com.tw 1 YB1921 3-Pin Microprocessor Reset Monitor Absolute Maximum Ratings (1) Parameter Value Symbol Unit Value Input Voltage VCC 5.5 V RESET -0.3 to (Vcc+0.3) V — 20 mA Output Current IOUT 20 mA Power Dissipation PD Internally Limited (3) — Output Short Circuit Duration — Infinite — Thermal Resistance, Junction-to-Ambient ΘJA 230 °C/W Operating Temperature Range TA 0~85 °C Lead Temperature (Soldering, 10 sec.) — 260 °C Junction Temperature TJ 0 to+125 °C Storage Temperature TS -60 to+150 °C Output Voltage Input Current Recommended Operating Conditions (2) Parameter Value Symbol Unit Min Type. Max Power Supply Voltage VCC 2.0 — 5.5 V Junction Temperature TJ 0 — +125 °C YB1921 www.yobon.com.tw 2 YB1921 3-Pin Microprocessor Reset Monitor Electrical Characteristics Vcc=5V for L/M/J; 3.3V for T/S; 3.0V for R, TA = 25°C, unless otherwise specified. Parameter Symbol Condition Min Typ Max Unit Input Voltage VCC — 2.0 — 5.5 V Supply Current ICC — — 18 25 μA 4.54 4.63 4.72 4.29 4.38 4.47 VTH YB1921L-4.63V YB1921M-4.38V YB1921J-4.00V YB1921T-3.08V YB1921S-2.93V YB1921R-2.63V 3.92 4.00 4.08 3.02 3.08 3.14 2.87 2.93 2.99 2.58 2.63 2.68 — — — 30 — ppm/°C — — — 20 — μsec Reset Active Timeout Period — — — 240 — msec RESET Output Voltage Low VOL ISINK = 3mA — — 0.4 V RESET Output Voltage High VOH ISOURCE = 800μA 0.8VCC — — V Reset Threshold Reset Threshold Temperature Coefficient (4) VCC to Reset Delay VCC = VTH to (VTH – 100mV) V Note 1: Exceeding the absolute maximum rating may damage the device. Note 2: The device is not guaranteed to function outside its operating rating. Note 3: The maximum allowable power dissipation at any TA (ambient temperature) is calculated using: PD (MAX) = (TJ (MAX) – TA)/ΘJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. See “Thermal Consideration” section for details Note 4: RESET threshold temperature coefficient is the worst case voltage change divided by the total temperature range. YB1921 www.yobon.com.tw 3 YB1921 3-Pin Microprocessor Reset Monitor Pin Description Pin Configuration VCC 3 S809La 2 1 RESET Pin No. Symbol 1 GND RESET 2 GND 3 Vcc Description Ground RESET output remains low while Vcc is below the reset voltage threshold and for 240msec(typ) after Vcc rises above reset threshold Supply Voltage (typ.) Ordering/Marking Information Package Reset Vcc Part Number Marking 4.63 YB1921LB-F S809La • 4.38 YB1921MB-F S809Ma • And underlined 9 is for year 2008 4.00 YB1921JB-F S809Ja • 2009, and underlined 8 for 2010. The naming 3.08 YB1921TB-F S809Ta • 2.93 YB1921SB-F S809Sa • 2.63 YB1921RB-F S809Ra • threshold (V) Marking Information Starting with 0, a bar underlined 0 is for production year 2006, on top of 9 is for year 2007. The next character is marked on top of 8 for pattern continues with consecutive characters for SOT-23 later years. The last character is the week code. (A-Z: 1-26, a-z: 27-52) A dot on top right corner is for lead-free process. Ordering Information YB1921 www.yobon.com.tw 4 YB1921 3-Pin Microprocessor Reset Monitor Dimension Outline Drawing For SOT-23 C J H B D A E G F K L INCHES SYMBOL YB1921 MILLIMETERS MIN MAX MIN MAX A 0.110 0.120 2.80 3.04 B 0.047 0.055 1.20 1.40 C 0.083 0.104 2.10 2.64 D 0.035 0.040 0.89 1.03 E 0.070 0.080 1.78 2.05 F 0.018 0.024 0.45 0.60 G 0.015 0.020 0.37 0.51 H 0.0005 0.004 0.013 0.10 J 0.034 0.040 0.887 1.02 K 0.003 0.007 0.085 0.18 L — 0.027 — 0.69 www.yobon.com.tw 5