LTC2916CTS8-1#TRPBF

LTC2915/LTC2916 Voltage Supervisor with 27 Selectable Thresholds FEATURES DESCRIPTION n The LTC®2915/LTC2916 are low voltage single-supply monitors with selectable thresholds. The parts operate from 1.5V to 5.5V and consume a quiescent current of only 30μA. n n n n n n n n n n 9 Selectable Supply Voltages 12V, 5V, 3.3V, 2.5V, 1.8V 1.5V, 1.2V, 1.0V, +ADJ (0.5V) 3 Selectable Tolerances –5%, –10%, –15% (LTC2915) Manual Reset Input (LTC2916) 1.5V to 5.5V Supply Operation 6.2V Shunt Regulator for High Voltage Operation Guaranteed Operation to 125˚C Guaranteed Threshold Accuracy: ±1.5% Low Quiescent Current: 30μA Typical Power Supply Glitch Immunity Guaranteed RST for VCC ≥ 0.8V Low Profile (1mm) 8-Lead TSOT-23 (ThinSOTTM) and (3mm × 2mm) DFN Packages APPLICATIONS n n n n n Two three-state inputs select one of nine internally programmed thresholds without the need for external resistors. For the LTC2915, an additional three-state input determines the tolerance (–5%, –10%, –15%). The tolerance for the LTC2916 is fixed at –5%. Threshold accuracy is guaranteed at ±1.5% over the entire operating temperature range. Glitch filtering ensures reliable reset operation without false triggering. The reset timeout may be set to 200ms or adjusted using an external capacitor. A separate manual reset input on the LTC2916 allows a simple push button interface. Operation to 125°C makes the LTC2915 and LTC2916 suitable for automotive applications. Handheld Devices Cell Phone Base Stations Automotive Control Systems Network Servers Optical Networking Systems L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 1.8V, –5% Tolerance Supply Monitor Monitor Selection Table 1.8V 10k LTC2916 VM RST RT SEL1 SEL2 MR GND SEL2 12V VCC VCC 5V VCC Open μP 3.3V VCC GND 2.5V Open VCC 1.8V Open Open 1.5V Open GND 1.2V GND VCC 1V GND Open ADJ (0.5V) GND GND RESET tRST = 200ms SEL1 VCC 0.1μF VCC NOMINAL VOLTAGE 29156 TA01 29156fa 1 LTC2915/LTC2916 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Terminal Voltages VCC (Note 3).......................................... –0.3V to 5.7V SEL1, SEL2, TOL, MR, RST .................. –0.3V to 7.5V VM ......................................................... –0.3V to 15V RT .............................................–0.3V to (VCC + 0.3)V Terminal Currents VCC (Note 3).......................................................±5mA Operating Temperature Range LTC2915C/LTC2916C ............................... 0°C to 70°C LTC2915I/LTC2916I.............................. –40°C to 85°C LTC2915H/LTC2916H ......................... –40°C to 125°C Storage Temperature Range................... –65°C to 150°C TS8 Lead Temperature (Soldering, 10 sec) ........... 300°C PIN CONFIGURATION TOP VIEW TOP VIEW VM 1 SEL1 2 TOL/MR 3 GND 4 8 VCC 7 SEL2 6 RT 5 RST GND 1 8 RST TOL/MR 2 7 RT 6 SEL2 5 VCC SEL1 3 9 VM 4 TS8 PACKAGE 8-LEAD PLASTIC TSOT-23 DDB PACKAGE 8-LEAD (3mm s 2mm) PLASTIC DFN TOL FOR LTC2915 MR FOR LTC2916 TJMAX = 150°C, θJA = 250°C/W TOL FOR LTC2915 MR FOR LTC2916 TJMAX = 150°C, θJA = 76°C/W EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2915CTS8-1#PBF LTC2915ITS8-1#PBF LTC2915HTS8-1#PBF LTC2915CDDB-1#PBF LTC2915IDDB-1#PBF LTC2915HDDB-1#PBF LTC2915CTS8-1#TRPBF LTC2915ITS8-1#TRPBF LTC2915HTS8-1#TRPBF LTC2915CDDB-1#TRPBF LTC2915IDDB-1#TRPBF LTC2915HDDB-1#TRPBF LTCVQ LTCVQ LTCVQ LCVR LCVR LCVR 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead (3mm × 2mm) Plastic DFN 8-Lead (3mm × 2mm) Plastic DFN 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C –40°C to 85°C –40°C to 125°C 0°C to 70°C –40°C to 85°C –40°C to 125°C LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2916CTS8-1#PBF LTC2916ITS8-1#PBF LTC2916HTS8-1#PBF LTC2916CDDB-1#PBF LTC2916IDDB-1#PBF LTC2916HDDB-1#PBF LTC2916CTS8-1#TRPBF LTC2916ITS8-1#TRPBF LTC2916HTS8-1#TRPBF LTC2916CDDB-1#TRPBF LTC2916IDDB-1#TRPBF LTC2916HDDB-1#TRPBF LTDCW LTDCW LTDCW LDCX LDCX LDCX 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead (3mm × 2mm) Plastic DFN 8-Lead (3mm × 2mm) Plastic DFN 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C –40°C to 85°C –40°C to 125°C 0°C to 70°C –40°C to 85°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 29156fa 2 LTC2915/LTC2916 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 2.5V, unless otherwise noted. (Note 2) SYMBOL PARAMETER VCC(MIN) Supply Voltage for Guaranteed RST Low RST Driven Low CONDITIONS l MIN VCC(UVLO) Supply Undervoltage Lockout l VCC(SHUNT) Shunt Regulation Voltage IVCC = 0.5mA l ICC VCC Pin Current SEL1, SEL2, TOL, MR = Open SEL1, SEL2, TOL = GND (LTC2915) MR = VCC (LTC2916) l l TYP MAX 0.8 5.7 UNITS V 1.5 V 6.2 7.0 V 30 45 50 80 μA μA Monitor Input (VM) VMT120 12V, 5% Reset Threshold 12V, 10% Reset Threshold 12V, 15% Reset Threshold l l l 11.04 10.44 9.84 11.22 10.62 10.02 11.40 10.80 10.20 V V V VMT50 5V, 5% Reset Threshold 5V, 10% Reset Threshold 5V, 15% Reset Threshold l l l 4.600 4.350 4.100 4.675 4.425 4.175 4.750 4.500 4.250 V V V VMT33 3.3V, 5% Reset Threshold 3.3V, 10% Reset Threshold 3.3V, 15% Reset Threshold l l l 3.036 2.871 2.706 3.086 2.921 2.756 3.135 2.970 2.805 V V V VMT25 2.5V, 5% Reset Threshold 2.5V, 10% Reset Threshold 2.5V, 15% Reset Threshold l l l 2.300 2.175 2.050 2.338 2.213 2.088 2.375 2.250 2.125 V V V VMT18 1.8V, 5% Reset Threshold 1.8V, 10% Reset Threshold 1.8V, 15% Reset Threshold l l l 1.656 1.566 1.476 1.683 1.593 1.503 1.710 1.620 1.530 V V V VMT15 1.5V, 5% Reset Threshold 1.5V, 10% Reset Threshold 1.5V, 15% Reset Threshold l l l 1.380 1.305 1.230 1.403 1.328 1.253 1.425 1.350 1.275 V V V VMT12 1.2V, 5% Reset Threshold 1.2V, 10% Reset Threshold 1.2V, 15% Reset Threshold l l l 1.104 1.044 0.984 1.122 1.062 1.002 1.140 1.080 1.020 V V V VMT10 1V, 5% Reset Threshold 1V, 10% Reset Threshold 1V, 15% Reset Threshold l l l 0.920 0.870 0.820 0.935 0.885 0.835 0.950 0.900 0.850 V V V VMTADJ ADJ (0.5V), 5% Reset Threshold ADJ (0.5V), 10% Reset Threshold ADJ (0.5V), 15% Reset Threshold l l l 460.0 435.0 410.0 467.5 442.5 417.5 475.0 450.0 425.0 mV mV mV RVM VM Input Impedance (Note 4) Fixed Threshold Modes l 0.5 8 MΩ IVM(ADJ) ADJ Input Current VM = 0.5V l ±15 nA 0.5 V Three-State Inputs (SEL1, SEL2), (TOL, LTC2915) VTPIN,LOW Low Level Input Voltage l VTPIN,HIGH High Level Input Voltage l VTPIN,Z Pin Voltage when Open ITPIN,Z Allowable Leakage in Open State ITPIN,H/L Pin Input Current ITPIN = 0μA VTPIN = 0V, VCC 1.4 V 0.9 V l ±5 μA l ±20 μA 29156fa 3 LTC2915/LTC2916 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 2.5V, unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Reset Timer Control (RT) IRT(UP) RT Pull-Up Current VRT = 0.25V l –2 –3 –4 μA IRT(DOWN) RT Pull-Down Current VRT = 1.1V l 2 3 4 μA IRT(INT) Internal RT VCC Detect Current VRT = VCC l 1 8 μA VRT(INT,LH) RT Internal Timer Threshold VRT Rising, Referenced to VCC l –100 –160 –300 mV tRST(INT) Internal Reset Timeout Period VRT = VCC l 150 200 260 ms tRST(EXT) Adjustable Reset Timeout Period CRT = 2.2nF l 16 20 25 ms tUV VM Undervoltage Detect to RST Asserted VM Less Than Reset Threshold VMTX by More Than 5% l 10 80 150 μs VOL Output Voltage Low RST VCC = 3.3V, IRST = 2.5mA VCC = 1V, IRST = 100μA VCC = 0.8V, IRST = 15μA l l l 0.15 0.15 0.05 0.4 0.3 0.2 V V V IOH(RST) RST Output Voltage High Leakage RST = VCC l ±1 μA 0.2 • VCC V Reset Output (RST) Manual Reset Input (LTC2916) VIL Input Low Voltage l VIH Input High Voltage l 0.8 • VCC RPU Pull Up Resistance l 50 Pulsewidth l 250 tPW 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. V 100 150 kΩ ns Note 3: VCC maximum pin voltage is limited by input current. Since the VCC pin has an internal 6.2V shunt regulator, a low impedance supply which exceeds 5.7V may exceed the rated terminal current. Operation from higher voltage supplies requires a series dropping resistor. See Applications Information. Note 4: Input impedance is dependent on the configuration of the SEL pins. TIMING DIAGRAM Monitor Input Timing VM VMTx tUV RST tRST 1V 29156 TD01 29156fa 4 LTC2915/LTC2916 TYPICAL PERFORMANCE CHARACTERISTICS Quiescent Supply Current vs Temperature 1.5 QUIESCENT SUPPLY CURRENT, ICC (μA) 40 0.5 VMTADJ 0 VMT25 –0.5 VMT120 –1.0 –1.5 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 SEL1 = 0V SEL2 = 2.5V TOL = OPEN 35 VCC = 5.5V VCC = 2.5V 30 VCC = 1.5V 25 20 –50 125 –25 75 0 25 50 TEMPERATURE (°C) 100 29156 G01 210 190 170 50 25 0 75 TEMPERATURE (°C) 100 125 ICC = 5mA 6.3 ICC = 1mA ICC = 100μA 6.2 6.1 –50 RST Output Voltage vs VCC 0 –25 0 25 50 75 TEMPERATURE (°C) 100 125 7.0 6.8 6.6 6.4 6.2 6.0 0.01 3 2 1 0 5 29156 G07 1 0.1 10 SUPPLY CURRENT, ICC (mA) 100 29156 G06 RST Pull-Down Current vs VCC PULL-DOWN CURRENT, IRST (mA) RST VOLTAGE (V) 50 29156 G03 RST VOL vs IRST 1.0 6 4 1 2 3 4 SUPPLY VOLTAGE, VCC (V) 100 29156 G05 6 0 150 Shunt Regulation Voltage vs Supply Current 6.4 29156 G04 100k PULL-UP TO VCC SEL1 = SEL2 = TOL = 0V 5 VM = 0.5V RESET OCCURS ABOVE CURVE 1 10 100 0.1 GLITCH PERCENTAGE PAST THRESHOLD (%) SHUNT REGULATION VOLTAGE, VCC(SHUNT) (V) SHUNT REGULATION VOLTAGE, VCC(SHUNT) (V) RESET TIMEOUT PERIOD (ms), tRST(INT) 230 –25 200 Shunt Regulation Voltage vs Temperature RT = VCC 150 –50 250 29156 G02 Internal Reset Timeout Period vs Temperature 250 300 125 5 NO PULL-UP R VCC = 2.5V 0.8 RST VOLTAGE (V) NORMALIZED VMTnn (%) 1.0 Allowable Glitch Duration vs Magnitude MAXIMUM ALLOWABLE GLITCH DURATION (μs) Threshold Voltage vs Temperature TA = 25°C unless otherwise noted. 4 RST AT 150mV 3 2 TA = 25°C 0.4 0.2 RST AT 50mV 1 TA = 125°C 0.6 0 0 0 1 2 3 4 SUPPLY VOLTAGE, VCC (V) 5 29156 G08 TA = –40°C 0 2 6 4 IRST (mA) 8 10 29156 G09 29156fa 5 LTC2915/LTC2916 PIN FUNCTIONS (TSOT/DFN) GND (Pin 4/Pin 1): Device Ground. MR (Pin 3/Pin 2) (LTC2916 only): Manual Reset Input (Active Low). A low level on the MR input causes the part to issue a reset, which is released one reset timeout after the input goes high. The pin has an internal 100k pull-up to VCC, and thus may interface directly to a momentary pushbutton. Leave open if unused. RST (Pin 5/Pin 8): Open Drain RST Output. Asserts low when VM is below the threshold selected by SEL1, SEL2 and TOL input pins. Held low for an adjustable timeout after VM input is above threshold. RT (Pin 6/Pin 7): Reset Timeout Control Pin. Attach an external Capacitor (CRT) to GND to set a reset timeout of 9ms/nF. Floating RT generates a reset timeout of approximately 400μs. Tie RT to VCC to generate a reset timeout of approximately 200ms. SEL1, SEL2 (Pins 2, 7/Pins 3, 6): Monitor Voltage Select Three-State Inputs. SEL1 and SEL2 control the nominal threshold voltage that VM is set to monitor. Connect to VCC, GND or leave unconnected in open state. (See Table 1). TOL (Pin 3/Pin 2) (LTC2915 only): Three-State Input for Supply Tolerance Selection (–5%, –10% or –15%). Controls the tolerance band at which the VM supply is monitored. Connect to VCC, GND, or leave unconnected in open state. (See Table 2). VCC (Pin 8/Pin 5): Power Supply Input. Bypass this pin to ground with a 0.1μF ceramic capacitor. A minimum of 1.5V on VCC ensures that the part is out of under voltage lockout and that the voltage thresholds are accurate. Operates as a direct supply input for voltages up to 5.5V. Operates as a shunt regulator for supply voltages greater than 5.7V and should have a resistor between this pin and the supply to limit VCC input current to no greater than 5mA. When used without a current-limiting resistor, pin voltage must not exceed 5.7V. VM (Pin 1/Pin 4): Voltage Monitor Input to RST Comparator. SEL1, SEL2 and TOL inputs select the exact threshold that asserts the RST output. Exposed Pad (Pin 9, DFN Only): Exposed Pad may be left open or connected to device ground. BLOCK DIAGRAM LTC2915 SEL1 SEL2 LTC2916 MR TOL RT VCC 3 STATE DECODE VCC VCC DETECT 100k VCC 6.2V MONITOR DIVIDER MATRIX VM + – 0.5V REFERENCE DIVIDER MATRIX – + INTERNAL 200ms TIMER RST RESET DRIVER LOGIC GND ADJUSTABLE RESET TIMER 29156 BD 29156fa 6 LTC2915/LTC2916 APPLICATIONS INFORMATION Supply Monitoring The LTC2915/LTC2916 are low voltage single supply monitors with selectable thresholds. Two three-state inputs select one of nine internally programmed thresholds. For the LTC2915, a third three-state input selects the tolerance at which the supply connected to the VM pin is monitored (–5%, –10%, –15%). The tolerance for the LTC2916 is fixed at –5%. Threshold accuracy is guaranteed at ±1.5% over the entire operating temperature range. The LTC2915/LTC2916 asserts the RST output low when VM is below the programmed threshold, and for a reset timeout (tRST) after VM goes above the threshold. The reset timeout can be configured to use an internal timer with no external components, or an adjusted timer programmed by placing an external capacitor from RT to ground. Power-Up VCC powers the drive circuits for the RST pin. Therefore, as soon as VCC reaches 0.8V during power up, the RST output asserts low. The SEL1 and SEL2 three-state input pins should be connected to GND, VCC or left unconnected during normal operation. Note that when left unconnected, the maximum leakage allowable from the pin to either GND or VCC is ±5μA. The tolerance at which the monitored supply is measured is set by the TOL pin (LTC2915 only), as shown in Table 2. If desired (e.g. for margining purposes), the TOL pin may be driven by a three-state buffer. That three-state buffer must have a VOL and VOH which meet the VIL and VIH of the TOL pin specified in the Electrical Characteristics, and maintain less than 5μA of leakage in the open state. Threshold Accuracy The trip threshold for VM is selected by configuring the three-state input pins. When using the adjustable input, an external resistive divider sets the trip threshold, allowing the user complete control over the trip point. Selection of this trip voltage is crucial to the reliability of the system. Table 1. Voltage Threshold Settings Until VCC reaches the undervoltage lockout threshold (guaranteed less than 1.5V), RST is held low regardless of the state of VM. NOMINAL VOLTAGE SEL1 SEL2 12V VCC VCC 5V VCC Open Once VCC is above the under voltage lockout threshold and VM is above the programmed threshold, the reset timer is started. After the reset timeout (tRST), the open drain pull-down releases RST and the external pull-up resistor pulls high. 3.3V VCC GND 2.5V Open VCC 1.8V Open Open 1.5V* Open GND 1.2V* GND VCC 1V* GND Open ADJ* (0.5V) GND GND Power-Down On power-down, once VM drops below its threshold or VCC drops below the undervoltage lockout, RST asserts logic low. Monitor Threshold Control The monitor threshold on the VM pin is controlled by the SEL1, SEL2 and TOL three-state pins. The SEL1 and SEL2 pins select one of nine preset nominal voltages (including one externally adjustable threshold) as shown in Table 1. *Require a separate supply for VCC Table 2. System Voltage Tolerance Settings TOLERANCE TOL –5% VCC –10% Open –15% GND 29156fa 7 LTC2915/LTC2916 APPLICATIONS INFORMATION Any power supply has some tolerance band within which it is expected to operate (e.g. 5V±10%). It is generally undesirable that a supervisor issue a reset when the power supply is inside this tolerance band. Such a “nuisance” reset reduces reliability by preventing the system from functioning under normal conditions. To prevent nuisance resets, the supervisor threshold must be guaranteed to lie outside the power supply tolerance band. To ensure that the threshold lies outside the power supply tolerance range, the nominal threshold must lie outside that range by the monitor’s accuracy specification. All 27 of the selectable thresholds have the same relative threshold accuracy of ±1.5% of the programmed nominal input voltage (over the full operating temperature range). Consider the example of monitoring a 5V supply with a 10% tolerance. The nominal threshold internal to the LTC2915 is 11.5% below the 5V input at 4.425V. With ±1.5% accuracy, the trip threshold range is 4.425V±75mV over temperature (i.e. 10% to 13% below 5.0V). The monitored system must thus operate reliably down to 4.35V or 13% below 5.0V over temperature. Glitch Immunity The above discussion is concerned only with the DC value of the monitored supply. Real supplies also have relatively high-frequency variation, from sources such as load transients, noise, and pickup. These variations should not be considered by the monitor in determining whether a supply voltage is valid or not. The variations may cause spurious outputs at RST, particularly if the supply voltage is near its trip threshold. Two techniques are used to combat spurious reset without sacrificing threshold accuracy. First, the timeout period helps prevent high-frequency variation whose frequency is above 1/ tRST from appearing at the RST output. When the voltage at VM goes below the threshold, the RST pin asserts low. When the supply recovers past the threshold, the reset timer starts (assuming it is not disabled), and RST does not go high until it finishes. If the supply becomes invalid any time during the timeout period, the timer resets and begins again when the supply next becomes valid. While the reset timeout is useful at preventing toggling of the reset output in most cases, it is not effective at preventing nuisance resets due to short glitches (due to load transients or other effects) on a valid supply. To reduce sensitivity to these short glitches, the comparator has additional anti-glitch circuitry. Any transient at the input of the comparator needs to be of sufficient magnitude and duration tUV before it can change the monitor state. The combination of the reset timeout and anti-glitch circuitry prevents spurious changes in output state without sacrificing threshold accuracy. Adjustable Input When the monitor threshold is configured as ADJ, the internal comparator input is connected to the pin without a resistive divider, and the pin is high-impedance. Thus, any desired threshold may be chosen by attaching VM to a tap point on an external resistive divider between the monitored supply and ground, as shown in Figure 1. The reference input of the comparator is controlled by the tolerance pin. The external resistive divider should make the voltage at VM = 0.5V when the supply is at nominal value. The actual threshold of VM accounts for the supply tolerance of ±1.5% guaranteed over the full operating temperature range. The resulting tolerances are –6.5%, –11.5%, –16.5% which correspond to 0.468V, 0.443V, 0.418V repectively. VMON R2 – VM R1 + + – 0.5V 29156 F01 Figure 1. Setting the Trip Point Using the Adjustable Threshold 29156fa 8 LTC2915/LTC2916 APPLICATIONS INFORMATION Typically, the user will pick a value of R1 based on acceptable current draw. Current used by the resistor divider will be approximately ⎛ 0.5V ⎞ R1= ⎜ ⎝ I ⎟⎠ RST Output Characteristics Recommended range of R1 is 1k to 1M. Higher values of resistance exacerbate the degradation of threshold accuracy due to leakage currents. If the nominal value of the supply being monitored is VNOM, then R2 = R1(2VNOM – 1) Resistor tolerances must be taken into account when determining the overall accuracy. Selecting the Reset Timing Capacitor The reset timeout period can be set to one of two fixed internal timers or set with a capacitor in order to accommodate a variety of applications. Connecting a capacitor, CRT, between the RT pin and ground sets the reset timeout period, tRST. The following formula approximates the value of capacitor needed for a particular timeout: CRT = tRST • 110 [pF/ms] For example, using a standard capacitor value of 2.2nF would give 20ms delay. Figure 2 shows the reset timeout period as a function of the value of the timer capacitor. RESET TIMEOUT PERIOD, tRST (ms) 10000 1000 The DC characteristics of the RST pull-down strength are shown in the Typical Performance Characteristics section. RST is an open-drain pin and thus requires an external pull-up resistor to the logic supply. RST may be pulled above VCC, providing the voltage limits of the pin are observed. The open-drain of the RST pin allows for wired-OR connection of several LTC2915/LTC2916s. As noted in the discussion of power up and power down, the circuits that drive RST are powered by VCC. During a fault condition, VCC of at least 1V ensures that RST pulls low. Manual Reset (LTC2916 Only) The LTC2916 includes the MR pin for applications where a manual reset is desired. MR is internally pulled up, allowing it to interface with a push button with no external components required. Asserting MR low when RST is high, initiates a reset, resulting in RST being asserted low for the set reset timeout. Shunt Regulator The LTC2915 and LTC2916 contain an internal 6.2V shunt regulator on the VCC pin to allow operation from a high voltage supply. To operate the part from a supply higher than 5.7V, the VCC pin must have a series resistor, RCC, to the supply. This resistor should be sized according to the following equation: VS(MAX ) − 5.7 V 100 5mA 10 ≤ RCC ≤ VS(MIN) − 7 V 250μA where VS(MIN) and VS(MAX) are the operating minimum and maximum of the supply. 1 0.1 0.001 Leaving RT open with no external capacitor generates a reset timeout of approximately 400μs. Shorting RT to VCC generates a reset timeout of approximately 200ms. 0.01 0.1 1 10 100 RT PIN CAPACITANCE, CRT (nF) 1000 29156 F02 As an example, consider operation from an automobile battery which might dip as low as 10V or spike to 60V. We must then pick a resistance between 10.86k and 12k. Figure 2. Reset Timeout Period vs RT Capacitance 29156fa 9 LTC2915/LTC2916 TYPICAL APPLICATIONS 12V Supply Monitor Powered from 12V, Utilizing Internal Shunt Regulator with 3.3V Logic Out 12V 5V, –10% Tolerance Supply Monitor with 200ms Internal Reset Timeout 3.3V 3.3V CBYPASS 0.1μF RPU 10k RCC 11k CBYPASS 0.1μF VCC VCC VCC VCC LTC2915 LTC2915 μP RST VM 5V RST SEL1 3.3V GND SEL2 SEL1 GND 29156 TA03 TOL GND RT RT 3.3V CRT 9V, –15% Tolerance Supply Monitor with 3.3V Logic Out 1V, –15% Tolerance Supply Monitor with 90ms Timeout 3.3V 9V CBYPASS 0.1μF R2 866k 3.3V CBYPASS 0.1μF RPU 10k μP RST LTC2915 RST SEL1 1V GND SEL2 μP RST VM RST SEL1 29156 TA04 TOL GND VCC VCC LTC2915 GND SEL2 29156 TA05 TOL GND RT RT CRT 0.01μF CRT 1.5V Supply Monitor with Tolerance Control for Margining, –5% Operation with –15% Margining 1.8V, –5% Supply Monitor with Manual Reset 1.8V RPU 10k VCC VCC VM R1 51.1k μP RST RST VM SEL2 29156 TA02 TOL GND RPU 10k 3.3V CBYPASS 0.1μF RPU 10k CBYPASS 0.1μF VCC RPU 10k VCC LTC2916 VM RST 1.5V 29156 TA07 MR MANUAL RESET PUSHBUTTON LTC2915 GND SEL2 GND VCC RST SEL1 10k* VCC μP VM μP RST RST I/O GND SEL1 –15% –5% SEL2 29156 TA08 RT GND CRT RT CRT *OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE 29156fa 10 LTC2915/LTC2916 PACKAGE DESCRIPTION TS8 Package 8-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1637) 0.52 MAX 2.90 BSC (NOTE 4) 0.65 REF 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.22 – 0.36 8 PLCS (NOTE 3) 0.65 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 1.95 BSC 0.09 – 0.20 (NOTE 3) TS8 TSOT-23 0802 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) R = 0.115 TYP 5 R = 0.05 TYP 0.40 ± 0.10 8 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 2.00 ±0.10 (2 SIDES) 0.56 ± 0.05 (2 SIDES) 0.75 ±0.05 0 – 0.05 4 0.25 ± 0.05 1 PIN 1 R = 0.20 OR 0.25 × 45° CHAMFER (DDB8) DFN 0905 REV B 0.50 BSC 2.15 ±0.05 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 29156fa 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. 11 LTC2915/LTC2916 TYPICAL APPLICATION Dual Supply Monitor (1.8V and 12V) with Manual Reset and 200ms Reset Timeout 1.8V CBYPASS 0.1μF RPU 10k VCC LTC2916 RST VM 12V VM SEL1 SEL1 SEL2 SEL2 MR MANUAL RESET PUSHBUTTON 1.8V GND VCC VCC LTC2915 RT 1.8V TOL GND μP RST RST GND 29156 TA10 RT 1.8V RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC690 5V Supply Monitor, Watchdog Timer and Battery Backup 4.65V Threshold LTC694-3.3 3.3V Supply Monitor, Watchdog Timer and Battery Backup 2.9V Threshold LTC1232 5V Supply Monitor, Watchdog Timer and Push-Button Reset 4.37V/4.62V Threshold LTC1326 Micro Power Precision Triple Supply Monitor 4.725V, 2.363V, 3.118V, 1V Threshold (±0.75%) LTC1726 Micro Power Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ Adjustable RESET and Watchdog Time-Outs LTC1727 Micro Power Triple Supply Monitor with Open-Drain Reset Individual Monitor Outputs in MSOP LTC1728 Micro Power Triple Supply Monitor with Open-Drain Reset 5-Lead SOT-23 Package LTC1985-1.8 Micro Power Triple Supply Monitor with Push-Pull Reset 5-Lead SOT-23 Package LTC2900 Programmable Quad Supply Monitor Adjustable RESET, 10-Lead MSOP and 3mm × 3mm 10-Lead DFN LTC2901 Programmable Quad Supply Monitor Adjustable RESET and Watchdog Timer, 16-Lead SSOP Package LTC2902 Programmable Quad Supply Monitor Adjustable RESET and Tolerance, 16-Lead SSOP Package, Margining LTC2903 Precision Quad Supply Monitor 6-Lead SOT-23 Package, Ultra Low Voltage Reset LTC2904/LTC2905 3-State Programmable Precision Dual Supply Monitor Adjustable RESET and Tolerance, 8-Lead SOT-23 Package LTC2906 Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Separate VCC Pin, RST/RST Outputs LTC2907 Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Separate VCC Pin, Adjustable Reset Timer LTC2908 Precision Six Supply Monitor (Four Fixed and 2 Adjustable) 8-Lead SOT-23 and DDB Packages LTC2909 Precision Triple/Dual Input UV, OV Monitor 2 ADJ Inputs, Monitors Negative Voltages LTC2910 Octal Positive/Negative Voltage Monitor 16-Lead SSOP and 5mm × 3mm DFN Packages LTC2912 Single UV/OV Voltage Monitor, Adjustable UV and OV Trip Values 8-Lead TSOT and 3mm × 2mm DFN Packages LTC2913 Dual UV/OV Voltage Monitor 10-Lead MOSP and 3mm × 3mm DFN Packages LTC2914 Qual UV/OV Positive/Negative Voltage Monitor 16-Lead SSOP and 5mm × 3mm DFN Packages 29156fa 12 Linear Technology Corporation LT 0108 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007