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| Global Mixed-mode Technology Inc. G680/G681 Microprocessor Reset IC Features High 2% Voltage Threshold Accuracy Independently Adjustable High- and LowVoltage Thresholds General Description The G680/G681 are microprocessor (P) supervisory circuits used to monitor the power supplies in P and digital systems. High- and Low- voltage thresholds can be adjusted independently, allowing for wide hysteresis. Voltage detection thresholds are accurate to 2%. 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. 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 (4A, typical) makes the G680/G681 ideal for use in portable equipment. The G680/G681 are available in 5 pin SOT 23-5 packages. 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 4A Supply Current Power Supply Transient Immunity 5-Pin SOT23-5 Packages Applications Computers Controllers Intelligent Instruments Critical P and C Power Monitoring Portable / Battery-Powered Equipment Automotive Ordering Information PART G680H(L)T1 G681LT1 TEMP. RANGE -40C ~ +105C -40C ~ +105C PIN-PACKAGE SOT23-5 SOT23-5 Pin Configuration Typical Operating Circuit VCC HTH 1 5 Vcc VCC HTH RPULL-UP * VCC GND 2 G680/G681 G680/G681 LTH RESET (RESET) GND P RESET INPUT GND LTH 3 SOT23-5 () is for G680H 4 RESET(RESET) *G681 ONLY Ver: 03 Preliminary Jan 25 2002 1 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. 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 G680/G681 Continuous Power Dissipation (TA = +70C) SOT23-5....................................................568mW Operating Temperature Range ...........-40C to +105C Storage Temperature Range...............-65C to +150C Lead Temperature (soldering, 10s) ...................+300C 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 = -40C to +105C, unless otherwise noted. Typical values are at TA = +25C, 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 RESET (RESET) Output Current Low RESET Output Current High (push-pull G680) RESET Open-Drain Output Leakage Current (G681L) SYMBOL ICC VTH VCC<5.5V CONDITION MIN 2.5 1.225 TYP MAX UNITS 4 1.25 70 15 420 5.5 7.5 1.272 V A V ppm/C s ms mA mA 1 A VLTH = VTH to VTH - 100mV 120 IOL IOH VCC = 2.5V, V RESET (VRESET) = 0.5V, RESET Asserted or RESET not asserted VCC = 2.5V, V RESET (VRESET) = 2V, RESET not asserted or RESET asserted. VHTH>VTH, RESET deasserted 8 2 860 Note 1: Production testing done at TA = +25C; limits over temperature guaranteed by design. Note 2: RESET output is for G680L/G681L; While RESET output is for G680H. Selector Guide PART / SUFFIX G680LT1 G680HT1 G681LT1 OUTPUT TYPE Push-pull RESET Push-pull RESET Open-Drain RESET TOP MARK 680A 680B 681A Ver: 03 Preliminary Jan 25 2002 2 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. Timing Diagram G680/G681 A VHTH VBATT VLTH 0V tRST VRESET VRESET VOH VOL VOH VOL tRST Propagation delays not shown for clarity. Functional Diagram VDD Low-Voltage Detect + LTH R High-Voltage Detect HTH One Shot S Delay Line Q RESET Q RESET + + 1.24V Bandgap Reference G680/G681 GND Ver: 03 Preliminary Jan 25 2002 3 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. Typical Operating Characteristics G680/G681 (VCC = full range, TA = -40C to +105C, unless otherwise noted. Typical values are at TA = +25C, VCC = 5V for 463/438/400 versions, VCC= 3.3V for 308/293 versions, and VCC = 3V for 263 version.) Supply Current vs. Temperature 5 4.5 4 Power -Down Reset Delay vs. Temperature 70 Vcc=5V Vcc=3.3V Vcc=2.5V Power-Down Reset Delay(S) 60 50 40 30 20 10 VOD=VTH-VLTH VOD=10mV Supply Current (uA) 3.5 3 2.5 2 1.5 1 0.5 0 -40 -20 0 20 40 60 80 VOD=100mV VOD=200mV 0 -40 -20 0 20 40 60 80 Temperature (C) Temperature(C) Reset Timeout Period vs. Temperature 800 700 600 500 400 300 200 100 0 1.002 Normalized Reset Threshold vs. Temperature Normalized Reset Threshold (V) 1 0.998 0.996 0.994 0.992 0.99 0.988 0.986 Reset Timeout Period (ms) VCC=5.5V VCC=3V -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 -40 -30 -20 -10 0 10 20 27 30 40 50 60 70 80 90 Temperature (C) Temperature (C) Ver: 03 Preliminary Jan 25 2002 4 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. Pin Description PIN 1 2 3 G680/G681 NAME HTH GND LTH FUNCTION High-Voltage Theshold (Input): Analog input to a comparator. When the level on this pin initially rises above VTH, the delay generator cycles and the RESET remains low or RESET remains high for a minimum of 140ms. Ground Low-Voltage Threshold (Input): Analog input to a comparator. This is the voltage monitor input assigned to detect a low voltage condition. When the level on this pin falls below VTH, RESET or RESET is asserted and the condition is latched until VHTH > VTH. Reset (Output): Push-pull output. This output is asserted and latched when VLTH 4 5 RESET (RESET) VCC Detailed Description A microprocessor's (P's) reset input starts the P 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. 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. 1400 Applications Information Negative-Going VCC Transients In addition to issuing a reset to the P 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 7s or less will not cause a reset pulse. A 0.1F bypass capacitor mounted as close as possible to the VLTH pin provides additional transient immunity. Programming the Thresholds The low-voltage threshold is calculated using: u s) Maximun Transient Duration ( 1200 1000 800 600 G69__463/438/400 VBAT (Io) = VREF R1+R2+R3 R2+R3 400 The low-voltage threshold is calculated using: G69__308/293/263 1 10 100 1000 200 VBAT (hi) = VREF 0 R1+R2+R3 R3 Reset Comparator Overdrive, Vth-Vcc (mV) where, for both equations: 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. Ver: 03 Preliminary Jan 25 2002 5 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. A value such as 1M 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 3M. V B A TT G680/G681 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. 1M VBAT (lo) =3.1V = 1.245 R2+344k R2 = 56k R1 = 1M - R2 - R3 R 1=600k R1 604k 1% G 6 8 0 /G 6 8 1 VCC LTH HTH RESET RESET The accuracy of the resistors can be chosen based upon the accuracy required by the system. R2 56k 1% VCC VCC RPULL-UP VCC R3 340k 1% G681 RESET P RESET MOTOROLA INPUT 68HCXX Figure 2. Example Circuit GND 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: 1M VBAT (hi) = 1.245 R3 R3 = 344k Figure 3. Interfacing to Ps with Bidirectional Reset I/O Interfacing to Ps with Bidirectional Reset Pins Since the RESET output on the G681L is open drain, this device interfaces easily with Ps that have bidirectional reset pins, such as the Motorola 68HC11. Connecting the P supervisor's RESET output directly to the microcontroller's (C's) RESET pin with a single pull-up resistor allows either device to assert reset (Figure 3). . Ver: 03 Preliminary Jan 25 2002 6 TEL: 886-3-5788833 http://www.gmt.com.tw Global Mixed-mode Technology Inc. Package Information D C G680/G681 L E H e1 e 1 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 1 MIN 1.00 0.00 0.70 0.35 0.10 2.70 1.40 --------2.60 0.37 1 DIMENSIONS IN MILLIMETERS NOM 1.10 ----0.80 0.40 0.15 2.90 1.60 1.90(TYP) 0.95 2.80 -----5 MAX 1.30 0.10 0.90 0.50 0.25 3.10 1.80 --------3.00 ----9 Taping Specification Feed Direction SOT23-5 Package Orientation Ver: 03 Preliminary Jan 25 2002 7 TEL: 886-3-5788833 http://www.gmt.com.tw |
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