LTC2932 Configurable Six Supply Monitor with Adjustable Reset Timer and Supply Tolerance DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Simultaneously Monitors Six Supplies 16 User Selectable Combinations of 5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and ± Adjustable Voltage Thresholds Guaranteed Threshold Accuracy: ±1.5% Selectable Supply Tolerances: 5%, 7.5%, 10%, 12.5% Below Monitored Voltage Reset Disable Pin for Margining Applications Low Supply Current: 52μA Power Supply Glitch Immunity Guaranteed RST for VCC ≥ 1V High Temperature Operation to 125°C 20-Lead TSSOP Package APPLICATIONS ■ ■ ■ ■ ■ ■ Desktop and Notebook Computers Multivoltage Systems Telecom Equipment Portable Battery-Powered Equipment Network Servers Automotive The LTC®2932 is a configurable supply monitor for systems with up to six supply voltages. One of 16 preset or adjustable voltage monitor combinations can be selected using an external resistive divider connected to the mode select pin. The preset voltage thresholds are digitally configurable to 5%, 7.5%, 10%, or 12.5% below the nominal operating voltage. The LTC2932 also features adjustable inputs with a 0.5V nominal threshold. All six open-drain voltage comparator outputs are connected to separate pins for individual supply monitoring. The reset timeout period is adjustable using an external capacitor. The RST output is guaranteed to be in the correct state for VCC down to 1V and may be disabled during supply margin testing. Each status output has a weak internal pull-up and may be externally pulled up to an external voltage. The 52μA supply current makes the LTC2932 ideal for power conscious systems and the part may be configured to monitor less than six inputs. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6967591, 7119714, 7239251. TYPICAL APPLICATION Six Supply Monitor 12V (ADJ), 5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ) Voltage Threshold Configuration Table V1 (V) V2 (V) V3 (V) V4 (V) V5 (V) 5 3.3 2.5 1.8 ADJ ADJ 5 3.3 2.5 1.5 ADJ ADJ 5 3.3 2.5 ADJ ADJ ADJ 5 3.3 1.8 ADJ ADJ ADJ 5 3.3 1.8 –ADJ ADJ ADJ 5 3.3 ADJ ADJ ADJ ADJ 5 3.3 ADJ –ADJ ADJ ADJ 5 3 2.5 ADJ ADJ ADJ V3 5 3 1.8 ADJ ADJ ADJ V4 5 3 ADJ ADJ ADJ ADJ 3.3 2.5 1.8 1.5 ADJ ADJ 3.3 2.5 1.8 ADJ ADJ ADJ 3.3 2.5 1.8 –ADJ ADJ ADJ 3.3 2.5 1.5 ADJ ADJ ADJ 3.3 2.5 ADJ ADJ ADJ ADJ 3.3 2.5 ADJ –ADJ ADJ ADJ 12V 5V 3.3V 2.5V SYSTEM LOGIC 1.8V 1.2V 10k POWER GOOD 0.1μF 0.1μF 100k 1% R1 59k 1% RDIS V6 VREF RST 2932 TA01 VPG GND R2 40.2k 1% COMP6 LTC2932 V5 100k 1% COMP5 COMP4 V2 COMP3 V1 COMP2 124k 1% COMP1 2150k 1% T0 T1 CRT tRST = 94ms CRT 47nF V6 (V) 2932fb 1 LTC2932 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 2, 3) TOP VIEW V1, V2, V3, V4, V5, V6, VPG ........................ –0.3V to 7V RST, COMP1-6, T0, T1................................. –0.3V to 7V CRT, VREF, RDIS ............................–0.3V to (VCC + 0.3V) Reference Load Current (IVREF) ..............................±1mA V4 Input Current (–ADJ Mode) ..............................–1mA RST, COMP1-6 Currents ......................................±10mA Operating Temperature Range LTC2932C ................................................ 0°C to 70°C LTC2932I..............................................– 40°C to 85°C LTC2932H ..........................................– 40°C to 125°C Storage Temperature Range...................– 65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C COMP5 1 20 COMP6 V5 2 19 V6 COMP3 3 18 COMP2 COMP1 4 17 COMP4 V3 5 16 V2 V1 6 15 V4 CRT 7 14 VREF RST 8 13 VPG T0 9 12 GND RDIS 10 11 T1 F PACKAGE 20-LEAD PLASTIC TSSOP TJMAX = 130°C, θJA = 90°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2932F#PBF LTC2932CF#TRPBF LTC2932F 20-Lead Plastic TSSOP 0°C to 70°C LTC2932F#PBF LTC2932IF#TRPBF LTC2932F 20-Lead Plastic TSSOP –40°C to 85°C LTC2932F#PBF LTC2932HF#TRPBF LTC2932F 20-Lead Plastic TSSOP –40°C to 125°C Consult LTC Marketing for information on non-standard lead based finish parts. *Temperature grades are identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ This product is only offered in trays. For more information go to: http://www.linear.com/packaging/ ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise specified. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VCC Minimum Internal Operating Voltage RST, COMPn in Correct Logic State ● 1 V VCCMINP Minimum Required for Mode Selection VCC Rising ● 2.4 V VCCMINC Minimum Required for Comparators VCC Falling ● 2.3 V VRT50 5V, 5% Reset Threshold 5V, 7.5% Reset Threshold 5V, 10% Reset Threshold 5V, 12.5% Reset Threshold V1 Input Threshold ● ● ● ● 4.600 4.475 4.350 4.225 4.675 4.550 4.425 4.300 4.750 4.625 4.500 4.375 V V V V VRT33 3.3V, 5% Reset Threshold 3.3V, 7.5% Reset Threshold 3.3V, 10% Reset Threshold 3.3V, 12.5% Reset Threshold V1, V2 Input Threshold ● ● ● ● 3.036 2.954 2.871 2.789 3.086 3.003 2.921 2.838 3.135 3.053 2.970 2.888 V V V V VRT30 3V, 5% Reset Threshold 3V, 7.5% Reset Threshold 3V, 10% Reset Threshold 3V, 12.5% Reset Threshold V2 Input Threshold ● ● ● ● 2.760 2.685 2.610 2.535 2.805 2.730 2.655 2.580 2.850 2.775 2.700 2.625 V V V V 2932fb 2 LTC2932 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise specified. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VRT25 2.5V, 5% Reset Threshold 2.5V, 7.5% Reset Threshold 2.5V, 10% Reset Threshold 2.5V, 12.5% Reset Threshold V2, V3 Input Threshold ● ● ● ● 2.300 2.238 2.175 2.113 2.338 2.275 2.213 2.150 2.375 2.313 2.250 2.188 V V V V VRT18 1.8V, 5% Reset Threshold 1.8V, 7.5% Reset Threshold 1.8V, 10% Reset Threshold 1.8V, 12.5% Reset Threshold V3, V4 Input Threshold ● ● ● ● 1.656 1.611 1.566 1.521 1.683 1.638 1.593 1.548 1.710 1.665 1.620 1.575 V V V V VRT15 1.5V, 5% Reset Threshold 1.5V, 7.5% Reset Threshold 1.5V, 10% Reset Threshold 1.5V, 12.5% Reset Threshold V3, V4 Input Threshold ● ● ● ● 1.380 1.343 1.305 1.268 1.403 1.365 1.328 1.290 1.425 1.388 1.350 1.313 V V V V VRTA ADJ, 5% Reset Threshold ADJ, 7.5% Reset Threshold ADJ, 10% Reset Threshold ADJ, 12.5% Reset Threshold V3, V4, V5, V6 Input Threshold ● ● ● ● 492.5 479.4 466.3 453.1 500.0 486.6 473.3 459.9 507.5 494 480.4 466.8 mV mV mV mV VRTAN –ADJ Reset Threshold V4 Input Threshold ● –18 0 18 mV VREF Reference Voltage VCC ≥ 2.3V, IVREF = ±1mA, CREF ≤ 1000pF T0 Low, T1 Low T0 Low, T1 High T0 High, T1 Low T0 High, T1 High ● ● ● ● 1.192 1.160 1.128 1.096 1.210 1.178 1.146 1.113 1.228 1.195 1.163 1.130 0 VPG Mode Selection Voltage Range VCC ≥ VCCMINP ● IVPG VPG Input Current VPG = VREF ● IV1 V1 Input Current V1 = 5V, IVREF = 12μA (Note 4) ● IV2 V2 Input Current V2 = 3.3V IV3 V3 Input Current IV4 V V V V VREF V ±20 nA 52 75 μA ● 0.8 2 μA V3 = 2.5V V3 = 0.55V (ADJ Mode) ● ● 0.52 1.2 ±15 μA nA V4 Input Current V4 = 1.8V V4 = 0.55V (ADJ Mode) V4 = –0.02V (–ADJ Mode) ● ● ● 0.34 0.8 ±15 ±15 μA nA nA IV5, IV6 V5, V6 Input Current V5, V6 = 0.55V ● ±15 nA ICRT(UP) CRT Pull-Up Current VCRT = GND ● –1.4 –2 –2.6 μA ICRT(DN) CRT Pull-Down Current VCRT = 1.3V ● 10 20 30 μA ICOMPn COMPn Pull-Up Current VCOMPn = GND ● –2 –6 –12 μA tRST Reset Timeout Period CRT = 1500pF ● 2 3 4 ms tUV Vn Undervoltage Detect to RST or COMPn Vn Less Than Reset Threshold by More than 1% VOL Voltage Output Low RST, COMPn ISINK = 3mA, VCC = 3V ISINK = 100μA, VCC = 1V ● ● VOH Voltage Output High RST, COMPn (Note 5) ISOURCE = –1μA ● 150 0.15 0.05 V2-1 μs 0.4 0.3 V V V 2932fb 3 LTC2932 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise specified. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Digital Inputs T0, T1, RDIS VIL T0, T1 Low Level Input Voltage VCC = 3.3V to 5.5V ● VIH T0, T1 High Level Input Voltage VCC = 3.3V to 5.5V ● IINTOL T0, T1 Input Current T0, T1 = 2V ● VIL RDIS Input Threshold Low VCC = 3.3V to 5.5V ● VIH RDIS Input Threshold High VCC = 3.3V to 5.5V ● 1.6 IRDIS RDIS Pull-Up Current VRDIS = 1V ● –4 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All currents into pins are positive, all voltages are referenced to GND unless otherwise noted. Note 3: The greater of V1, V2 is the internal supply voltage (VCC). 0.3VCC 0.7VCC V V ±0.1 ±1 μA 0.4 V V –10 –16 μA Note 4: Under static no-fault conditions, V1 will necessarily supply quiescent current. If at any time V2 is larger than V1, V2 must be capable of supplying the quiescent current, programming (transient) current and reference load current. Note 5: The output pins RST and COMPn have diode protected internal pull-ups to V2 of typically 6μA. However, external pull-up resistors may be used when faster rise times are required or for VOH voltages greater than V2. TIMING DIAGRAM Vn Monitor Timing Vn VRT tUV tRST RST 2932 TD COMPn 2932fb 4 LTC2932 TYPICAL PERFORMANCE CHARACTERISTICS –ADJ Threshold Voltage vs Temperature 1.010 1.005 1.000 0.995 0.990 0.985 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 VREF vs Temperature 18 1.228 12 1.222 6 1.216 VREF (V) 1.015 THRESHOLD VOLTAGE, VRTAN (mV) NORMALIZED THRESHOLD VOLTAGES (V/V) Normalized Threshold Voltages vs Temperature 0 –6 1.204 –12 1.198 –18 –50 –25 125 50 25 75 0 TEMPERATURE (°C) 100 2932 G01 TYPICAL TRANSIENT DURATION (μs) 300 125°C IV4 (A) –1μ –100n 50 –10n 45 –1n 90°C 25°C 100 125 –100p –300 –250 –200 –150 –100 V4 (mV) –50 TA = 25°C 250 200 RESET OCCURS ABOVE CURVE 150 100 50 0 0 0.1 1 10 100 RESET COMPARATOR OVERDRIVE (% OF VRTX) 2932 G05 2932 G04 2932 G06 RST Output Voltage vs V1, VPG = GND 375 5 TA = 25°C 10k PULL-UP FROM RST TO V1 5 300 RESET OCCURS ABOVE CURVE 225 150 75 RST OUTPUT VOLTAGE (V) TYPICAL TRANSIENT DURATION (μs) 6 TA = 25°C Reset Timeout Period vs Temperature RESET TIMEOUT PERIOD, tRST (ms) Transient Duration vs Comparator Overdrive (V3, V4, V5, V6) 450 4 3 2 1 0 0.1 1 10 100 RESET COMPARATOR OVERDRIVE (% OF VRTX) 2932 G07 125 100 Transient Duration vs Comparator Overdrive (V1,V2) –10μ 55 50 75 25 0 TEMPERATURE (°C) 2932 G03 –100μ V1 = 5V V2 = 3.3V 65 V3 = 2.5V V4 = 1.8V V5 = V6 = 1V 60 50 25 75 0 TEMPERATURE (°C) 1.192 –50 –25 I(V4) vs V4 in Negative Adjust Mode 70 SUPPLY CURRENT, IV1 (μA) 125 2932 G02 Supply Current vs Temperature 40 –50 –25 1.210 0 0 1 2 3 4 5 V1 (V) 2932 G08 CRT = 1500pF (SILVER MICA) 4 3 2 1 –50 –25 75 0 25 50 TEMPERATURE (°C) 100 125 2932 G09 2932fb 5 LTC2932 TYPICAL PERFORMANCE CHARACTERISTICS ISINK vs Supply Voltage (RST, COMPn) Reset Timeout Period vs CRT 15 TA = 25°C V1 = 5V V2 = 3V 125°C 400 12 VOL = 0.4V 100m ISINK (mA) RESET TIMEOUT PERIOD tRST (s) 1 500 TA = 25°C 10m 85°C 9 VOL (mV) 10 Voltage Output Low vs Output Sink Current (RST, COMPn) VOL = 0.2V 6 300 25°C 200 1m –40°C 100 3 100μ 10μ 10p 100p 1n 10n CRT (F) 100n 0 1μ 0 1 3 2 V1 OR V2 (V) 0 4 5 2 0 6 4 ISINK (mA) 2932 G10 8 2932 G11 250 COMPn PROPAGATION DELAY (μs) TA = 25°C COMPn = GND PULL-UP CURRENT (μA) 15 12 9 6 3 0 1 2 3 V2 (V) 4 5 2932 G13 RST Pull-Up Current vs V2 18 TA = 25°C 150 V1, V2 100 50 0 TA = 25°C 15 200 PULL-UP CURRENT (μA) 18 2932 G12 COMPn Propagation Delay vs Input Overdrive Above Threshold COMPn Pull-Up Current vs V2 10 V3, V4, V5, V6 12 9 VRT33 VRT30 6 3 VRT25 1000 10 100 INPUT OVERDRIVE ABOVE THRESHOLD (mV) 2932 G14 0 2.0 2.5 3.0 3.5 V2 (V) 4.0 4.5 5.0 2932 G15 2932fb 6 LTC2932 PIN FUNCTIONS COMP5 (Pin 1): Comparator Output 5. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V5 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. V5 (Pin 2): Adjustable Voltage Input 5. High impedance comparator input with 0.5V typical threshold. See Applications Information for details. Tie to V1 if unused. COMP3 (Pin 3): Comparator Output 3. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V3 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. COMP1 (Pin 4): Comparator Output 1. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V1 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. V3 (Pin 5): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V, or ADJ. See Applications Information for details. Tie to V1 if unused. V1 (Pin 6): Voltage Input 1. Select from 5V or 3.3V. See Applications Information for details. The greater of V1 or V2 is also VCC for the device. Bypass this pin to ground with a 0.1μF (or greater) capacitor. CRT (Pin 7): Reset Timeout Capacitor. Attach an external capacitor (CRT) to GND to set a reset timeout of 2ms/nF. Leaving the pin open generates a minimum delay of approximately 25μs. A 47nF capacitor generates a 94ms reset delay time. RST (Pin 8): Reset Output. Logic output with weak 6μA pull-up to V2. Pulls low when any voltage input is below the reset threshold and held low for the configured delay time after all voltage inputs are above threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. T0 (Pin 9): Supply Tolerance Selection Input. Used in conjunction with T1 (Pin 11). See Applications Information for tolerance selection chart (Table 2). Choose from 5%, 7.5%, 10% or 12.5%. RDIS (Pin 10): Digital Input for RST Disable. A low input on this pin forces RST to V2 (or to the pull-up voltage). Useful for determining supply margins without issuing a reset. A weak internal pull-up allows pin to be left open for normal monitor operation. T1 (Pin 11): Supply Tolerance Selection Input. Used in conjunction with T0 (Pin 9). See Applications Information for tolerance selection chart (Table 2). Choose from 5%, 7.5%, 10% or 12.5%. GND (Pin 12): Ground. VPG (Pin 13): Threshold Select Input. Connect to an external 1% resistive divider between VREF and GND to select 1 of 16 combinations and/or ±adjustable voltage thresholds (see Table 1). Do not add capacitance on the VPG pin. VREF (Pin 14): Buffered Reference Voltage Output. A 1.210V nominal reference used for the mode selection voltage (VPG) and for the offset of negative adjustable applications. The buffered reference can source and sink up to 1mA. The reference can drive a bypass capacitor of up to 1000pF without oscillation. V4 (Pin 15): Voltage Input 4. Select from 1.8V, 1.5V, ADJ or –ADJ. See Applications Information for details. Tie to V1 if unused and configured for positive voltage. V2 (Pin 16): Voltage Input 2. Select from 3.3V, 3V or 2.5V. See Applications Information for details. The greater of V1, V2 is also VCC for the device. Bypass this pin to ground with a 0.1μF (or greater) capacitor. All status outputs are weakly pulled up to V2. COMP4 (Pin 17): Comparator Output 4. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V4 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. COMP2 (Pin 18): Comparator Output 2. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V2 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. 2932fb 7 LTC2932 PIN FUNCTIONS V6 (Pin 19): Adjustable Voltage Input 6. High impedance comparator input with 0.5V typical threshold. See Applications Information for details. Tie to V1 if unused. COMP6 (Pin 20): Comparator Output 6. Real-time logic output with weak 6μA pull-up to V2. Pulls high when V6 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. BLOCK DIAGRAM T0 V1 9 T1 BUFFER GAIN ADJUST 11 POWER DETECT VCC BUFFER VREF BANDGAP REFERENCE 14 V2 V2 V2 VRTA 6μA V2 6μA VPG 13 A/D COMP1 4 V2 6μA 4 COMP2 18 COMP3 3 6μA V1 6 V2 16 V3 5 RESISTIVE DIVIDER MATRIX 4 – 4 + COMP4 17 V2 CMP1-4 4 6μA V2 COMP5 1 V4 15 6μA V5 – 2 COMP6 20 + V2 CMP5 6μA VRTA RST 4 + CMP6 V6 19 CRT – 8 ADJUSTABLE RESET PULSE GENERATOR 2μA VCC 22μA 10μA 7 VCC CRT RDIS 10 2932 BD GND 12 2932fb 8 LTC2932 APPLICATIONS INFORMATION Supply Monitoring The LTC2932 is a low power, high accuracy configurable six supply monitoring circuit with six real-time monitor outputs, a common reset output, a reset disable function and selectable supply thresholds. An external capacitor sets the reset timeout period. An external resistive divider between VREF, VPG and GND selects 1 of 16 possible input voltage monitor combinations. All six voltage inputs must be above their predetermined thresholds for the reset not to be activated. The LTC2932 asserts the reset and comparator outputs during power-up, power-down and brownout conditions on any one of the voltage inputs. Power-Up The greater of V1 and V2 serves as the internal supply voltage (VCC). On power-up, VCC powers the drive circuits for the RST pin. This ensures that the RST output will be low as soon as either V1 or V2 reaches 1V. The RST output remains low until the part is configured. Once the voltage thresholds are set, if any of the supply monitor inputs is below its configured threshold, RST will be a logic low. Once all the monitor inputs rise above their thresholds, an internal timer is started and RST is released after the delay time. If VCC < (V3 – 1.0V) and VCC < 2.4V, the V3 input impedance will be low (10kΩ typical). Threshold Accuracy Consider a 5V system with ±5% tolerance. The 5V supply may vary between 4.75V to 5.25V. System ICs powered by this supply must operate reliably within this band (and a little more as explained below). A perfectly accurate supervisor for this supply generates a reset at exactly 4.75V, however no supervisor is this perfect. The actual reset threshold of a supervisor varies over a specified band; the LTC2932 varies ±1.5% around its nominal threshold voltage (see Figure 1) over temperature. The reset threshold band and the power supply tolerance bands should not overlap. This prevents false or nuisance resets when the power supply is actually within its specified tolerance band. NOMINAL SUPPLY VOLTAGE 5V SUPPLY TOLERANCE MINIMUM RELIABLE SYSTEM VOLTAGE IDEAL SUPERVISOR THRESHOLD 4.75V ±1.5% THRESHOLD BAND –5% 4.675V –6.5% 4.6V –8% REGION OF POTENTIAL MALFUNCTION Figure 1. 1.5% Threshold Accuracy Improves System Reliability The LTC2932 has a ±1.5% reset threshold accuracy, so a “5%” threshold is typically set to 6.5% below the nominal input voltage. Therefore, a typical 5V, “5%” threshold is 4.675V. The threshold is guaranteed to lie in the band between 4.750V and 4.600V over temperature. The powered system must work reliably down to the low end of the threshold band, or risk malfunction before a reset signal is properly issued. A less accurate supervisor increases the required system voltage margin and increases the probability of system malfunction. The LTC2932’s ±1.5% specification improves the reliability of the system over supervisors with wider threshold tolerances. Monitor Configuration and Tolerance Selection Select the LTC2932 input voltage combination by placing the recommended resistive divider from VREF to GND and connecting the tap point to VPG, as shown in Figure 2. Table 1 offers recommended 1% resistor values for each of the 16 modes. The last column in Table 1 specifies optimum VPG/VREF ratios (± 0.01), when configuring with a ratiometric DAC. LTC2932 VREF VPG GND R1 1% R2 1% 2932 F02 Figure 2. Mode Selection 2932fb 9 LTC2932 APPLICATIONS INFORMATION Table 2. Tolerance Selection Table 1. Voltage Threshold Modes* MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ) VPG VREF T0 T1 TOLERANCE (%) VREF (V) 1.210 Low Low 5 0 5 3.3 ADJ ADJ Open Short 0.000 Low High 7.5 1.178 1 5 3.3 ADJ –ADJ 93.1 9.53 0.094 High Low 10 1.146 2 3.3 2.5 ADJ ADJ 86.6 16.2 0.156 High High 12.5 1.113 3 3.3 2.5 ADJ –ADJ 78.7 22.1 0.219 4 3.3 2.5 1.5 ADJ 71.5 28 0.281 5 5 3.3 2.5 ADJ 66.5 34.8 0.344 VSUPPLY (V) VTRIP (V) R3 (kΩ) R4 (kΩ) 6 5 3.3 2.5 1.8 59 40.2 0.406 12 11.25 2150 100 7 5 3.3 2.5 1.5 53.6 47.5 0.469 10 9.4 1780 100 8 5 3 2.5 ADJ 47.5 53.6 0.531 8 7.5 1400 100 7 1300 100 Table 3. Suggested 1% Resistor Values for the ADJ Inputs 9 5 3 ADJ ADJ 40.2 59 0.594 7.5 10 3.3 2.5 1.8 1.5 34.8 66.5 0.656 6 5.6 1020 100 4.725 845 100 3.055 511 100 11 3.3 2.5 1.8 ADJ 28 71.5 0.719 5 12 3.3 2.5 1.8 –ADJ 22.1 78.7 0.781 3.3 13 5 3.3 1.8 –ADJ 16.2 86.6 0.844 14 5 3.3 1.8 ADJ 9.53 93.1 0.906 15 5 3 1.8 ADJ Short Open 1 *V5 and V6 are always adjustable (ADJ). At power-up, once V1 or V2 reaches 2.4V, the monitor enters a setup period of approximately 150μs. During the setup time, the voltage on the VPG pin is sampled and the monitor is configured to the desired input combination. The comparators are enabled and supply monitoring begins. Do not add capacitance to the VPG pin. The two supply tolerance inputs, T0 and T1, configure the global supply tolerance. Larger tolerances provide more headroom by lowering the trip thresholds. Table 2 lists the input combinations for each of the tolerance modes. 3 2.82 464 100 2.5 2.325 365 100 1.8 1.685 237 100 1.5 1.410 182 100 1.2 1.120 124 100 1 0.933 86.6 100 0.9 0.840 68.1 100 *See Figure 3. Table 4. Suggested 1% Resistor Values for the –ADJ Inputs VSUPPLY (V) VTRIP (V) R3 (kΩ) R4 (kΩ) –2 –1.87 187 121 –5 –4.64 464 121 –5.2 –4.87 487 121 –10 –9.31 931 121 –12 –11.30 1130 121 *See Figure 4. VTRIP LTC2932 R3 1% VREF V3, V4, V5 OR V6 R4 1% R4 1% LTC2932 V4 R3 1% + – 0.5V 5% TOLERANCE MODE VTRIP 2932 F03 Figure 3. Setting the Positive Adjustable Trip Point 2932 F04 Figure 4. Setting the Negative Adjustable Trip Point 2932fb 10 LTC2932 APPLICATIONS INFORMATION Using the Adjustable Thresholds The reference inputs on the V3 and/or V4 comparators are set to 0.5V when the positive adjustable modes are selected (Figure 3). The reference inputs on the V5 and V6 comparators are always set to 0.5V. The tap point on an external resistive divider, connected between the positive voltage being sensed and ground, is connected to the high impedance, adjustable inputs (V3, V4, V5, V6). Calculate the trip voltage from: R3 VTRIP = 0.5V • 1+ R4 In the negative adjustable mode, the reference level on the V4 comparator is connected to ground (Figure 4). The tap point on an external resistive divider, connected between the negative voltage being sensed and the VREF pin, is connected to the high impedance adjustable input (V4). VREF provides the necessary level shift required to operate at ground. The negative trip voltage is calculated from: VTRIP = −VREF • R3 ; V = 1.210V Nominal REF R4 T0, T1 Low (5% Tolerance Mode) Once the resistor divider is set in the 5% tolerance mode, there is no need to change the divider for the other tolerance modes (7.5%, 10%, 12.5%) because VREF is scaled accordingly, moving the trip point in –2.5% increments. In a negative adjustable application, the minimum value for R4 is limited by the sourcing capability of VREF (±1mA). With no other load on VREF, R4 (minimum) is: 1.210V = 1.210kΩ 1mA Tables 3 and 4 offer suggested 1% resistor values for various positive and negative supply adjustable applications assuming 5% monitor thresholds. Although all six supply monitor comparators have builtin glitch immunity, bypass capacitors on V1 and V2 are recommended because the greater of V1 or V2 is also the VCC for the device. Filter capacitors on the V3, V4, V5 and V6 inputs are allowed. Power-Down On power-down, once any of the monitor inputs drops below its threshold, RST is held at a logic low. A logic low of 0.4V is guaranteed until both V1 and V2 drop below 1V. If the bandgap reference becomes invalid (VCC < 2V typical), the LTC2932 will enter the 150μs setup period when VCC rises above 2.4V (max). Selecting the Reset Timing Capacitor The reset timeout period is adjustable in order to accommodate a variety of microprocessor applications. The reset timeout period, tRST, is adjusted by connecting a capacitor, CRT, between the CRT pin and ground. The value of this capacitor is determined by: CRT = tRST = 500 [pF / ms] • tRST 2MΩ Leaving the CRT pin unconnected generates a minimum reset timeout of approximately 25μs. Maximum reset timeout is limited by the largest available low leakage capacitor. The accuracy of the timeout period is affected by capacitor leakage (the nominal charging current is 2μA) and capacitor tolerance. A low leakage ceramic capacitor is recommended. Reset Disable Under conventional operation, RST and COMPn will go low when Vn is below its threshold. At any time, the RDIS pin can be pulled low, overriding the reset operation and forcing the RST pin high. This feature is useful when determining supply margins under processor control since the reset command will not be invoked. The RDIS pin is connected to a weak internal pull-up to VCC (10μA typical), allowing the pin to be left open if unused. 2932fb 11 LTC2932 APPLICATIONS INFORMATION Six Supply Monitor with Hysteresis The LTC2932 monitors six supply voltages in Figure 5 and is configured to mode 6 (see Table 1). Supply tolerance inputs T0 and T1 are tied to RST. As the LTC2932 powers up, RST is low, which keeps the tolerance at 5%. After all six inputs exceed their 5% threshold voltages, RST pulls high. This changes the supply tolerance to 12.5%. If any of the input voltages drop below the 12.5% threshold level, reset is asserted. The push button on V6 also allows for a manual reset when pressed. Five Supply Power-up Sequencer In Figure 6, the LTC2932’s real-time COMP outputs are used to enable DC/DC converters sequentially. The system is powered by a 12V source. The system is started when the push-button is pressed and the LTC2950-1 brings the RUN pin of the LTM4600 high. Subsequently, the LTM4600 generates a 5V output which applies power to each of the 4 DC/DC converters. The LTC2932 is configured to mode 13 and a 12.5% threshold (see Tables 1 and 2). When the threshold is reached on V1, COMP1 pulls high. COMP1 then enables the 3.3V converter first. When the threshold is reached on V2, COMP2 pulls high and enables the 1.8V converter next. When all the converters have been enabled and are good, COMP5 pulls high. RST pulls high 9.4ms after COMP5. Figure 7 shows the power-up sequence of the five supplies and the DONE and RST outputs. If the KILL input on the LTC2950-1 does not receive a logic high from the RST output within 512ms of initial power-up, EN pulls low and the LTM4600 is powered down. In the event that the external 12V supply drops below 9.6V, COMP6 and RST pull low. The LTC2950-1 then receives a logic low on the KILL input, which powers down the LTM4600 and the sequencing circuit. 5V 10k 0.1μF 10k 10k 10k 10k 10k 10k LTC2932 3.3V 2.5V 1.8V 2150k 1% 12V 1.2V 124k 1% V1 COMP1 V2 COMP2 V3 COMP3 V4 COMP4 V5 COMP5 V6 COMP6 RST VREF R1 59k 1% T0 GND CRT PUSHBUTTON 100k 1% R2 40.2k 1% 100k 1% *OPTIONAL FOR EXTENDED ESD TOLERANCE 2932 F05 T1 VPG 10k* SYSTEM LOGIC RDIS CRT 47nF tRST = 94ms Figure 5. Six Supply Monitor with Hysteresis 5% Tolerance (Supplies Rising) 12.5% Tolerance (After RST Goes High) 2932fb 12 LTC2932 APPLICATIONS INFORMATION 12V (9.6V THRESHOLD) LTM4600 VIN VOUT 5V 5V RUN VIN VIN LTC2950-1 VIN INT PB LT3028 VOUT 1.8V 1.8V SYSTEM LOGIC LTC3704 VOUT –5.2V VIN 10k –5.2V RUN/UVLO VIN 10k 3.3V SHDN 10k KILL 10k SHDN 10k EN 10k LT3028 VOUT 3.3V LT3028 VOUT 2.5V 2.5V SHDN DONE 12V SUPPLY STATUS COMP1 COMP2 COMP3 COMP4 COMP5 COMP6 2932 F06 V1 10k 0.1μF 365k 1% 487k 1% 1820k 1% V2 T0 V3 T1 V4 V5 LTC2932 RDIS V6 RST 100k 1% 100k 1% 121k 1% VREF R1 16.2k 1% R2 86.6k 1% VPG CRT GND 4.7nF tRST = 9.4ms Figure 6. Five Supply 12.5% Tolerance Power-Up Sequencer with Pushbutton 2932fb 13 LTC2932 APPLICATIONS INFORMATION PB 5V 3.3V 2.5V 1.8V –5.2V DONE RST 2932 FO7 Figure 7. Five Supply Power-Up Sequencing (Based on Circuit in Figure 6) 2932fb 14 LTC2932 PACKAGE DESCRIPTION F Package 20-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1650) 6.40 – 6.60* (.252 – .260) 1.05 p0.10 6.60 p0.10 20 19 18 17 16 15 14 13 12 11 4.50 p0.10 0.45 p0.05 6.40 (.252) BSC 0.65 BSC 1 2 3 4 5 6 7 8 9 10 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50** (.169 – .177) 0.09 – 0.20 (.0035 – .0079) 0.50 – 0.75 (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 0.25 REF 1.10 (.0433) MAX 0o – 8o 0.65 (.0256) BSC 0.19 – 0.30 (.0075 – .0118) TYP 0.05 – 0.15 (.002 – .006) F20 TSSOP 0204 3. DRAWING NOT TO SCALE *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED .152mm (.006") PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE 2932fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LTC2932 TYPICAL APPLICATION Five Supply Adjustable Threshold Monitor with LED Indicators 5V 0.1μF 1k 1k 1k 1k 1k LTC2932 3.3V 2150k 1% 12V 1.2V 124k 1% 1V 86.6k 1% V1 COMP1 V2 COMP2 V3 COMP3 V4 COMP4 V5 COMP5 V6 COMP6 RST VREF 100k 1% 100k 1% 100k 1% TO SYSTEM RESET RDIS CRT VPG GND 2932 TA02 T0 T1 CRT 47nF tRST = 94ms RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1326 Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ 4.725V, 3.118V, 1V Threshold (±0.75%) and ADJ LTC1728 Micropower Triple Supply Monitor with Open-Drain Reset 5-Lead SOT-23 Package LTC2900 Programmable Quad Supply Monitor Adjustable Reset, 10-Lead MSOP and DFN Packages LTC2901 Programmable Quad Supply Monitor Adjustable Reset and Watchdog Timer LTC2902 Programmable Quad Supply Monitor Adjustable Reset and Tolerance (5%, 7.5%, 10%, or 12.5%) LTC2903 Precision Quad Supply Monitor 6-Lead SOT-23 Package LTC2904-LTC2907 Three-State Programmable Precision Dual Supply Monitor 8-Lead SOT-23 and DFN Packages LTC2908 Precision Six Supply Monitor (Four Fixed & Two Adjustable) 8-Lead TSOT-23 and DFN Packages LTC2909 Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Shunt Regulated VCC Pin, Adjustable Threshold and Reset, 8-Lead SOT-23 and DFN Packages LTC2910 Precision Octal Positive/Negative Voltage Supply Monitor 16-Lead SSOP and 5mm × 3mm DFN Packages, H-Grade Temperature Range LTC2912-LTC2914 Single/Dual/Quad UV and OV Voltage Monitors Separate VCC Pin, Adjustable Reset Timer, H-Grade Temperature Range LTC2915-LTC2918 Single Supply Monitor with 27 Pin-Selectable Thresholds Manual Reset, Watchdog, TSOT-8/MSOP-10 and 3mm × 2mm DFN Packages, H-Grade Temperature Range LTC2928 Quad Power Supply Sequencer and Supervisor Easily Configure Power Management without Software, 36-Lead 5mm × 7mm QFN and SSOP Packages LTC2930 Configurable Six Supply Monitor with Adjustable Reset Timer, Manual Reset 3mm × 3mm DFN-12 Package, H-Grade Temperature Range LTC2931 Configurable Six Supply Monitor with Adjustable Reset and Watchdog Timers TSSOP-20 Package, H-Grade Temperature Range, Individual Supply Comparator Outputs 2932fb 16 Linear Technology Corporation LT 0408 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008