G680/G681 Global Mixed-mode Technology Inc. Microprocessor Reset IC Features General Description High ±2% Voltage Threshold Accuracy Independently Adjustable High- and Low- The G680/G681 are microprocessor (µP) supervisory circuits used to monitor the power supplies in µP and digital systems. High- and Low- voltage thresholds can be adjusted independently, allowing for wide hysteresis. Voltage detection thresholds are accurate to 2%. Voltage Thresholds Fully Specified Over Temperature Available in Three Output Configurations Push-Pull RESET Output (G680L) Push-Pull RESET Output (G680H) Open-Drain RESET Output (G681L) 140ms min Power-On Reset Pulse Width 4µA Supply Current Power Supply Transient Immunity 5-Pin SOT23-5 Packages These circuits perform a single function: they assert a reset signal whenever the VCC supply voltage declines below the low-voltage threshold, keeping it asserted for at least 140ms after VCC has risen above the high-voltage threshold. The G681L has an open-drain output stage, while the G680 have push-pull outputs. The G681L’s open-drain RESET output requires a pull-up resistor that can be connected to a voltage higher than VCC. The G680L have an active-low RESET output, while the G680H has an active-high RESET output. The reset comparator is designed to ignore fast transients on threshold input. Applications Computers Controllers Intelligent Instruments Critical µP and µC Power Monitoring Portable / Battery-Powered Equipment Automotive The IC’s power supply is separate from the detector inputs, allowing the G680/G681 to be powered from a down-stream supply. Low supply current (4µA, typical) makes the G680/G681 ideal for use in portable equipment. The G680/G681 are available in 5 pin SOT 23-5 packages. Ordering Information Pin Configuration PART TEMP. RANGE PIN-PACKAGE G680H(L)T1 G681LT1 -40°C ~ +105°C -40°C ~ +105°C SOT23-5 SOT23-5 Typical Operating Circuit VCC HTH 1 5 Vcc VCC VCC RPULL-UP* HTH GND 2 G680/G681 G680/G681 LTH 4 LTH 3 RESET(RESET) RESET (RESET) GND µP RESET INPUT GND SOT23-5 *G681 ONLY () is for G680H TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 1 Global Mixed-mode Technology Inc. G680/G681 Absolute Maximum Ratings Terminal Voltage (with respect to GND) VCC.……………………………..……………-0.3V to +6.0V Input Voltage (VLTH, VHTH)…..……….-0.3V to (VCC + 0.3V) RESET, RESET (push-pull)....…......-0.3V to (VCC + 0.3V) RESET (open drain)...…........…........…....-0.3V to +6.0V Input Current, VCC ............................……................20mA Output Current, RESET, RESET ..….....................20mA Continuous Power Dissipation (TA = +70°C) SOT23-5…………………………………………….568mW Operating Temperature Range …....….-40°C to +105°C Storage Temperature Range..…...…….-65°C to +150°C Lead Temperature (soldering, 10s) ...…....…......+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics (VCC = full range, TA = -40°C to +105°C, unless otherwise noted. Typical values are at TA = +25°C, VCC = 3.3V (Note 1) PARAMETER VCC Range Supply Current (SOT23) Reset Threshold Reset Threshold Tempco VLTH to Reset Delay (Note 2) Reset Active Timeout Period SYMBOL CONDITION TYP MAX UNITS 2.5 ICC VTH VCC<5.5V 1.225 VLTH = VTH to VTH – 100mV 120 RESET (RESET) Output Current Low IOL VCC = 2.5V, V RESET (VRESET) = 0.5V, RESET Asserted or RESET not asserted RESET Output Current High (push-pull G680) IOH VCC = 2.5V, V RESET (VRESET) = 2V, RESET not asserted or RESET asserted. RESET Open-Drain Output Leakage Current (G681L) MIN 4 1.25 70 15 420 5.5 7.5 1.272 860 V µA V ppm/°C µs ms 8 mA 2 mA 1 VHTH>VTH, RESET deasserted µA Note 1: Production testing done at TA = +25°C; limits over temperature guaranteed by design. Note 2: RESET output is for G680L/G681L; While RESET output is for G680H. Selector Guide PART / SUFFIX OUTPUT TYPE TOP MARK G680LT1 Push-pull RESET 680A G680HT1 Push-pull RESET 680B G681LT1 Open-Drain RESET 681A TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 2 G680/G681 Global Mixed-mode Technology Inc. Timing Diagram A VHTH VBATT VLTH 0V VRESET VOH VOL VRESET VOH VOL tRST tRST Propagation delays not shown for clarity. Functional Diagram VDD Low-Voltage Detect + LTH Q RESET S Q RESET One Shot High-Voltage Detect HTH R + Delay Line + 1.24V Bandgap Reference G680/G681 GND TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 3 G680/G681 Global Mixed-mode Technology Inc. Typical Operating Characteristics (VCC = full range, TA = -40°C to +105°C, unless otherwise noted. Typical values are at TA = +25°C, VCC = 5V for 463/438/400 versions, VCC= 3.3V for 308/293 versions, and VCC = 3V for 263 version.) Power -Down Reset Delay vs. Temperature Supply Current vs. Temperature 70 Vcc=5V 4 Supply Current (uA) Power-Down Reset Delay(μS) 5 4.5 Vcc=3.3V 3.5 Vcc=2.5V 3 2.5 2 1.5 1 0.5 VOD=VTH-VLTH 60 VOD=10mV 50 40 30 20 VOD=100mV 10 VOD=200mV 0 0 -40 -20 0 20 40 60 -40 80 0 20 40 60 80 Normalized Reset Threshold vs. Temperature Reset Timeout Period vs. Temperature 800 1.002 700 Normalized Reset Threshold (V) Reset Timeout Period (ms) -20 Temperature(°C) Temperature (°C) VCC=5.5V 600 500 VCC=3V 400 300 200 100 0 -40 -30 -20 -10 0 1 0.998 0.996 0.994 0.992 0.99 0.988 0.986 -40 -30 -20 -10 0 10 20 27 30 40 50 60 70 80 90 10 20 30 40 50 60 70 80 90 Temperature (°C) Temperature (°C) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 4 Global Mixed-mode Technology Inc. G680/G681 Pin Description PIN NAME FUNCTION High-Voltage Theshold (Input): Analog input to a comparator. When the level on this pin initially 1 HTH rises above VTH, the delay generator cycles and the RESET remains low or RESET remains high 2 GND for a minimum of 140ms. Ground Low-Voltage Threshold (Input): Analog input to a comparator. This is the voltage monitor input 3 LTH assigned to detect a low voltage condition. When the level on this pin falls below VTH, RESET or 4 RESET (RESET) 5 VCC RESET is asserted and the condition is latched until VHTH > VTH. Reset (Output): Push-pull output. This output is asserted and latched when VLTH <VTH, indicating a low voltage condition. This state remains latched until VHTH > VTH. The polarity of this signal (active-high or low) is determined by the part number suffix. See ordering information. Power Supply (Input): Independent supply input for internal circuitry. Detailed Description Applications Information A microprocessor’s (µP’s) reset input starts the µP in a known state. The G681L/G680L/G680H assert reset to prevent code-execution errors during power-up, power-down, or brownout conditions. They assert a reset signal whenever the threshold voltage declines below VTH, keeping it asserted for at least 140ms after threshold voltage input has risen above the reset threshold. The G681L uses an open-drain output, and the G680L/G680H have a push-pull output stage. Connect a pull-up resistor on the G681L’s RESET output to any supply between 0 and 5.5V. Negative-Going VCC Transients In addition to issuing a reset to the µP during power-up, power-down, and brownout conditions, the G681L/G680H/G680L are relatively immune to shortduration negative-going VLTH transients (glitches). Figure1. shows typical transient duration vs. reset comparator overdrive, for which the G681L/G680H/ G680L do not generate a reset pulse. The graph was generated using a negative-going pulse applied to VLTH, starting 0.1V above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the maximum pulse width a negative-going VLTH transient can have without causing a reset pulse. As the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, a VLTH transient that goes 100mV below the reset threshold and lasts 7µs or less will not cause a reset pulse. A 0.1µF bypass capacitor mounted as close as possible to the VLTH pin provides additional transient immunity. Battery voltage is monitored by a comparator via a voltage divider network. The divided voltage is compared to an internal reference voltage. When the voltage at the LTH input pin drops below the internal reference voltage, the output is asserted. At this point, the voltage at HTH is assumed to be below the reference voltage. Maximun Transient Duration ( u s) 1400 1200 Programming the Thresholds The low-voltage threshold is calculated using: 1000 800 600 VBAT (Io) = VREF G69__463/438/400 R1+R2+R3 R2+R3 The low-voltage threshold is calculated using: 400 G69__308/293/263 200 VBAT (hi) = VREF 0 1 10 100 R1+R2+R3 R3 1000 where, for both equations: Reset Comparator Overdrive, Vth-Vcc (mV) VBAT (hi) = 1.245V Figure1. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive In order to provide the additional criteria needed to solve for the resistor values, the resistors can be selected such that they have a given total value, that is, R1 + R2 + R3 = RTOTAL. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 5 G680/G681 Global Mixed-mode Technology Inc. Once R3 is determined, the equation for VBAT (lo) can be used to determine R2. A single lithium-ion cell should not be discharged below 2.5V. Many applications limit the drain to 3.1V. Using 3.1V for the V BAT (lo) threshold allows calculation of the two remaining resistor values. 1MΩ VBAT (lo) =3.1V = 1.245 R2+344k A value such as 1MΩ for RTOTAL is a reasonable value because it draws minimum battery current but has no measurable effect on accuracy. When working with large resistors, a small amount of leakage current can cause voltage offsets that degrade system accuracy. The maximum recommended total resistance from VBAT to ground is 3MΩ. R2 = 56kΩ R1 = 1MΩ - R2 - R3 V B A TT R 1=600kΩ R1 604k 1% The accuracy of the resistors can be chosen based upon the accuracy required by the system. G 6 8 0 /G 6 8 1 VCC LTH RESET RESET HTH R2 VCC 56k 1% VCC VCC RPULL-UP R3 340k 1% G681 RESET µP RESET MOTOROLA INPUT 68HCXX Figure 2. Example Circuit GND Once the desired trip points are determined, set the VBAT(hi) threshold first. For example, use a total of 1M = R1 + R2 + R3. For a typical single-cell lithium ion battery, 3.6V is a good “high threshold” because at 3.6V the battery is moderately charged. Solving for R3: GND Figure 3. Interfacing to µPs with Bidirectional Reset I/O Interfacing to µPs with Bidirectional Reset Pins Since the RESET output on the G681L is open drain, this device interfaces easily with µPs that have bidirectional reset pins, such as the Motorola 68HC11. Connecting the µP supervisor’s RESET output di- 1MΩ VBAT (hi) = 1.245 R3 R3 = 344kΩ rectly to the microcontroller’s (µC’s) RESET pin with a single pull-up resistor allows either device to assert reset (Figure 3). . TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 6 G680/G681 Global Mixed-mode Technology Inc. Package Information C D L E H θ1 e1 e A A2 A1 b 1. 2. 3. 4. Note: Package body sizes exclude mold flash protrusions or gate burrs Tolerance ±0.1000 mm (4mil) unless otherwise specified Coplanarity: 0.1000mm Dimension L is measured in gage plane SYMBOLS A A1 A2 b C D E e e1 H L θ1 MIN DIMENSIONS IN MILLIMETERS NOM 1.00 0.00 0.70 0.35 0.10 2.70 1.40 --------2.60 0.37 1º 1.10 ----0.80 0.40 0.15 2.90 1.60 1.90(TYP) 0.95 2.80 -----5º MAX 1.30 0.10 0.90 0.50 0.25 3.10 1.80 --------3.00 ----9º Taping Specification Feed Direction SOT23-5 Package Orientation TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 03 Preliminary Jan 25 2002 7