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LTC2915/LTC2916 Voltage Supervisor with 27 Selectable Thresholds FEATURES
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DESCRIPTION
The LTC(R)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 30A. 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 125C makes the LTC2915 and LTC2916 suitable for automotive applications.
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.
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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 125C Guaranteed Threshold Accuracy: 1.5% Low Quiescent Current: 30A Typical Power Supply Glitch Immunity Guaranteed RST for VCC 0.8V Low Profile (1mm) 8-Lead TSOT-23 (ThinSOTTM) and (3mm x 2mm) DFN Packages
APPLICATIONS
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Handheld Devices Cell Phone Base Stations Automotive Control Systems Network Servers Optical Networking Systems
TYPICAL APPLICATION
1.8V, -5% Tolerance Supply Monitor
1.8V 0.1F VCC LTC2916 VM RT MR GND RST SEL1 SEL2 tRST = 200ms 10k VCC P RESET
29156 TA01
Monitor Selection Table
NOMINAL VOLTAGE 12V 5V 3.3V 2.5V 1.8V 1.5V 1.2V 1V ADJ (0.5V) SEL1 VCC VCC VCC Open Open Open GND GND GND SEL2 VCC Open GND VCC Open GND VCC Open GND
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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 ............................... 0C to 70C LTC2915I/LTC2916I.............................. -40C to 85C LTC2915H/LTC2916H ......................... -40C to 125C Storage Temperature Range................... -65C to 150C TS8 Lead Temperature (Soldering, 10 sec) ........... 300C
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 TOL/MR 2 SEL1 3 VM 4 9 8 7 6 5 RST RT SEL2 VCC
TS8 PACKAGE 8-LEAD PLASTIC TSOT-23 TOL FOR LTC2915 MR FOR LTC2916 TJMAX = 150C, JA = 250C/W
DDB PACKAGE 8-LEAD (3mm 2mm) PLASTIC DFN TOL FOR LTC2915 MR FOR LTC2916 TJMAX = 150C, JA = 76C/W EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL
ORDER INFORMATION
LEAD FREE FINISH LTC2915CTS8-1#PBF LTC2915ITS8-1#PBF LTC2915HTS8-1#PBF LTC2915CDDB-1#PBF LTC2915IDDB-1#PBF LTC2915HDDB-1#PBF LEAD FREE FINISH LTC2916CTS8-1#PBF LTC2916ITS8-1#PBF LTC2916HTS8-1#PBF LTC2916CDDB-1#PBF LTC2916IDDB-1#PBF LTC2916HDDB-1#PBF TAPE AND REEL LTC2915CTS8-1#TRPBF LTC2915ITS8-1#TRPBF LTC2915HTS8-1#TRPBF LTC2915CDDB-1#TRPBF LTC2915IDDB-1#TRPBF LTC2915HDDB-1#TRPBF TAPE AND REEL LTC2916CTS8-1#TRPBF LTC2916ITS8-1#TRPBF LTC2916HTS8-1#TRPBF LTC2916CDDB-1#TRPBF LTC2916IDDB-1#TRPBF LTC2916HDDB-1#TRPBF PART MARKING* LTCVQ LTCVQ LTCVQ LCVR LCVR LCVR PART MARKING* LTDCW LTDCW LTDCW LDCX LDCX LDCX PACKAGE DESCRIPTION 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead (3mm x 2mm) Plastic DFN 8-Lead (3mm x 2mm) Plastic DFN 8-Lead (3mm x 2mm) Plastic DFN PACKAGE DESCRIPTION 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead TSOT-23 8-Lead (3mm x 2mm) Plastic DFN 8-Lead (3mm x 2mm) Plastic DFN 8-Lead (3mm x 2mm) Plastic DFN TEMPERATURE RANGE 0C to 70C -40C to 85C -40C to 125C 0C to 70C -40C to 85C -40C to 125C TEMPERATURE RANGE 0C to 70C -40C to 85C -40C to 125C 0C to 70C -40C to 85C -40C to 125C
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/
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LTC2915/LTC2916 ELECTRICAL CHARACTERISTICS
SYMBOL VCC(MIN) VCC(UVLO) VCC(SHUNT) ICC PARAMETER Supply Undervoltage Lockout Shunt Regulation Voltage VCC Pin Current IVCC = 0.5mA SEL1, SEL2, TOL, MR = Open SEL1, SEL2, TOL = GND (LTC2915) MR = VCC (LTC2916)
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 2.5V, unless otherwise noted. (Note 2)
CONDITIONS
l l l l l
MIN 0.8
TYP
MAX 1.5
UNITS V V V A A
Supply Voltage for Guaranteed RST Low RST Driven Low
5.7
6.2 30 45
7.0 50 80
Monitor Input (VM) VMT120 12V, 5% Reset Threshold 12V, 10% Reset Threshold 12V, 15% Reset Threshold 5V, 5% Reset Threshold 5V, 10% Reset Threshold 5V, 15% Reset Threshold 3.3V, 5% Reset Threshold 3.3V, 10% Reset Threshold 3.3V, 15% Reset Threshold 2.5V, 5% Reset Threshold 2.5V, 10% Reset Threshold 2.5V, 15% Reset Threshold 1.8V, 5% Reset Threshold 1.8V, 10% Reset Threshold 1.8V, 15% Reset Threshold 1.5V, 5% Reset Threshold 1.5V, 10% Reset Threshold 1.5V, 15% Reset Threshold 1.2V, 5% Reset Threshold 1.2V, 10% Reset Threshold 1.2V, 15% Reset Threshold 1V, 5% Reset Threshold 1V, 10% Reset Threshold 1V, 15% Reset Threshold ADJ (0.5V), 5% Reset Threshold ADJ (0.5V), 10% Reset Threshold ADJ (0.5V), 15% Reset Threshold VM Input Impedance (Note 4) ADJ Input Current Low Level Input Voltage High Level Input Voltage Pin Voltage when Open Allowable Leakage in Open State Pin Input Current VTPIN = 0V, VCC ITPIN = 0A
l l l l l l l l l l l l l l l l l l l l l l l l l l l l l
11.04 10.44 9.84 4.600 4.350 4.100 3.036 2.871 2.706 2.300 2.175 2.050 1.656 1.566 1.476 1.380 1.305 1.230 1.104 1.044 0.984 0.920 0.870 0.820 460.0 435.0 410.0 0.5
11.22 10.62 10.02 4.675 4.425 4.175 3.086 2.921 2.756 2.338 2.213 2.088 1.683 1.593 1.503 1.403 1.328 1.253 1.122 1.062 1.002 0.935 0.885 0.835 467.5 442.5 417.5
11.40 10.80 10.20 4.750 4.500 4.250 3.135 2.970 2.805 2.375 2.250 2.125 1.710 1.620 1.530 1.425 1.350 1.275 1.140 1.080 1.020 0.950 0.900 0.850 475.0 450.0 425.0 8 15 0.5
V V V V V V V V V V V V V V V V V V V V V V V V mV mV mV M nA V V V
VMT50
VMT33
VMT25
VMT18
VMT15
VMT12
VMT10
VMTADJ
RVM IVM(ADJ) VTPIN,LOW VTPIN,HIGH VTPIN,Z ITPIN,Z ITPIN,H/L
Fixed Threshold Modes VM = 0.5V
l l l l
Three-State Inputs (SEL1, SEL2), (TOL, LTC2915) 1.4 0.9 5 20
A A
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LTC2915/LTC2916 ELECTRICAL CHARACTERISTICS
SYMBOL IRT(UP) IRT(DOWN) IRT(INT) VRT(INT,LH) Reset Output (RST) tRST(INT) tRST(EXT) tUV VOL Internal Reset Timeout Period Adjustable Reset Timeout Period VM Undervoltage Detect to RST Asserted Output Voltage Low RST VRT = VCC CRT = 2.2nF VM Less Than Reset Threshold VMTX by More Than 5% VCC = 3.3V, IRST = 2.5mA VCC = 1V, IRST = 100A VCC = 0.8V, IRST = 15A RST = VCC
l l l l l l l l l l l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 2.5V, unless otherwise noted. (Note 2)
PARAMETER RT Pull-Up Current RT Pull-Down Current Internal RT VCC Detect Current RT Internal Timer Threshold CONDITIONS VRT = 0.25V VRT = 1.1V VRT = VCC VRT Rising, Referenced to VCC
l l l l
MIN -2 2 -100 150 16 10
TYP -3 3 1 -160 200 20 80 0.15 0.15 0.05
MAX -4 4 8 -300 260 25 150 0.4 0.3 0.2 1 0.2 * VCC
UNITS A A A mV ms ms s V V V A V V k ns
Reset Timer Control (RT)
IOH(RST) VIL VIH RPU tPW
RST Output Voltage High Leakage Input Low Voltage Input High Voltage Pull Up Resistance Pulsewidth
Manual Reset Input (LTC2916) 0.8 * VCC 50 250 100 150
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: 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 1V
29156 TD01
tRST
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LTC2915/LTC2916 TYPICAL PERFORMANCE CHARACTERISTICS
Threshold Voltage vs Temperature
1.5 QUIESCENT SUPPLY CURRENT, ICC (A) 1.0 NORMALIZED VMTnn (%) 0.5 0 -0.5 -1.0 -1.5 -50 -25 VMT25 VMT120 40
TA = 25C unless otherwise noted. Allowable Glitch Duration vs Magnitude
MAXIMUM ALLOWABLE GLITCH DURATION (s) 300 250 200 150 100 50 0 1 10 100 0.1 GLITCH PERCENTAGE PAST THRESHOLD (%)
29156 G03
Quiescent Supply Current vs Temperature
SEL1 = 0V SEL2 = 2.5V TOL = OPEN VCC = 5.5V 30 VCC = 2.5V VCC = 1.5V 25
35
VMTADJ
RESET OCCURS ABOVE CURVE
50 25 75 0 TEMPERATURE (C)
100
125
20 -50
-25
75 0 25 50 TEMPERATURE (C)
100
125
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Internal Reset Timeout Period vs Temperature
RESET TIMEOUT PERIOD (ms), tRST(INT) RT = VCC SHUNT REGULATION VOLTAGE, VCC(SHUNT) (V) 250 6.4
Shunt Regulation Voltage vs Temperature
ICC = 5mA SHUNT REGULATION VOLTAGE, VCC(SHUNT) (V) 7.0
Shunt Regulation Voltage vs Supply Current
230
6.8
6.3 ICC = 1mA
210
6.6
190
6.2
ICC = 100A
6.4
170
6.2
150 -50
-25
50 25 0 75 TEMPERATURE (C)
100
125
6.1 -50
-25
0 25 50 75 TEMPERATURE (C)
100
125
6.0 0.01
1 0.1 10 SUPPLY CURRENT, ICC (mA)
100
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RST Output Voltage vs VCC
6 PULL-DOWN CURRENT, IRST (mA) 100k PULL-UP TO VCC SEL1 = SEL2 = TOL = 0V 5 VM = 0.5V RST VOLTAGE (V) 4 3 2 1 0 0 1 2 3 4 SUPPLY VOLTAGE, VCC (V) 5
29156 G07
RST Pull-Down Current vs VCC
6 5 4 RST AT 150mV 3 2 1 0 0 1 2 3 4 SUPPLY VOLTAGE, VCC (V) 5
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RST VOL vs IRST
1.0 NO PULL-UP R VCC = 2.5V
0.8 RST VOLTAGE (V) TA = 125C 0.6 TA = 25C 0.4
RST AT 50mV
0.2
TA = -40C
0
0
2
6 4 IRST (mA)
8
10
29156 G09
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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 approxi. mately 400s. 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 0.1F 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 TOL LTC2916 MR VCC 3 STATE DECODE 100k VCC DETECT VCC VCC 6.2V VM MONITOR DIVIDER MATRIX RT
INTERNAL 200ms TIMER RESET DRIVER LOGIC
RST
+ -
0.5V
REFERENCE DIVIDER MATRIX
6
+ -
GND ADJUSTABLE RESET TIMER
29156 BD
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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. Until VCC reaches the undervoltage lockout threshold (guaranteed less than 1.5V), RST is held low regardless of the state of VM. 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. 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. 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 5A. 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 5A 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
NOMINAL VOLTAGE 12V 5V 3.3V 2.5V 1.8V 1.5V* 1.2V* 1V* ADJ* (0.5V) *Require a separate supply for VCC SEL1 VCC VCC VCC Open Open Open GND GND GND SEL2 VCC Open GND VCC Open GND VCC Open GND
Table 2. System Voltage Tolerance Settings
TOLERANCE -5% -10% -15% TOL VCC Open GND
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LTC2915/LTC2916 APPLICATIONS INFORMATION
Any power supply has some tolerance band within which it is expected to operate (e.g. 5V10%). 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 4.425V75mV 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
R1
+ -
0.5V
Figure 1. Setting the Trip Point Using the Adjustable Threshold
8
+
29156 F01
-
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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 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.
10000 RESET TIMEOUT PERIOD, tRST (ms)
Leaving RT open with no external capacitor generates a reset timeout of approximately 400s. Shorting RT to VCC generates a reset timeout of approximately 200ms. RST Output Characteristics 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 5mA RCC VS(MIN) - 7 V 250A
1000
100
10
1
where VS(MIN) and VS(MAX) are the operating minimum and maximum of the supply.
0.01 0.1 1 10 100 RT PIN CAPACITANCE, CRT (nF) 1000
0.1 0.001
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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.
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Figure 2. Reset Timeout Period vs RT Capacitance
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LTC2915/LTC2916 TYPICAL APPLICATIONS
12V Supply Monitor Powered from 12V, Utilizing Internal Shunt Regulator with 3.3V Logic Out
12V RCC 11k CBYPASS 0.1F VCC LTC2915 VM SEL1 SEL2 TOL GND RT CRT 3.3V RST RST GND
29156 TA02
5V, -10% Tolerance Supply Monitor with 200ms Internal Reset Timeout
3.3V CBYPASS 0.1F
3.3V RPU 10k VCC P 5V 3.3V
RPU 10k VCC
VCC LTC2915 VM SEL1 SEL2 TOL GND RT RST RST GND
29156 TA03
P
9V, -15% Tolerance Supply Monitor with 3.3V Logic Out
9V 3.3V CBYPASS 0.1F R2 866k RPU 10k VCC VCC LTC2915 VM SEL1 R1 51.1k SEL2 TOL GND RT CRT RST RST GND
29156 TA04
1V, -15% Tolerance Supply Monitor with 90ms Timeout
3.3V CBYPASS 0.1F VCC RPU 10k VCC P RST RST GND
29156 TA05
P 1V VM
LTC2915 SEL1 SEL2 TOL GND RT CRT 0.01F
1.8V, -5% Supply Monitor with Manual Reset
1.8V CBYPASS 0.1F VCC LTC2916 VM SEL1 SEL2 MR 10k* MANUAL RESET PUSHBUTTON GND RT RST RST GND
29156 TA07
1.5V Supply Monitor with Tolerance Control for Margining, -5% Operation with -15% Margining
3.3V
RPU 10k
VCC P 1.5V VM SEL1 SEL2 GND RT VCC LTC2915 RST
CBYPASS 0.1F
RPU 10k VCC P RST I/O GND
-15% -5%
29156 TA08
CRT
CRT
*OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE
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LTC2915/LTC2916 PACKAGE DESCRIPTION
TS8 Package 8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637)
0.52 MAX 0.65 REF 2.90 BSC (NOTE 4)
1.22 REF
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC
1.50 - 1.75 (NOTE 4) PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR
0.65 BSC
0.22 - 0.36 8 PLCS (NOTE 3)
0.80 - 0.90 0.20 BSC 1.00 MAX DATUM `A' 0.01 - 0.10
0.30 - 0.50 REF
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
0.09 - 0.20 (NOTE 3)
1.95 BSC
TS8 TSOT-23 0802
DDB Package 8-Lead Plastic DFN (3mm x 2mm)
(Reference LTC DWG # 05-08-1702 Rev B)
0.61 0.05 (2 SIDES) 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) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 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
3.00 0.10 (2 SIDES)
R = 0.05 TYP
R = 0.115 TYP 5
0.40 0.10 8
PIN 1 BAR TOP MARK (SEE NOTE 6)
2.00 0.10 (2 SIDES) 0.56 0.05 (2 SIDES) 0.75 0.05
0.200 REF
4 0.25 0.05 2.15 0.05 (2 SIDES)
1 0.50 BSC
PIN 1 R = 0.20 OR 0.25 x 45 CHAMFER
(DDB8) DFN 0905 REV B
0 - 0.05
BOTTOM VIEW--EXPOSED PAD
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 0.1F VCC LTC2916 VM SEL1 SEL2 MR MANUAL RESET PUSHBUTTON GND RT 1.8V 1.8V RST 12V VM SEL1 SEL2 TOL GND RT 1.8V VCC LTC2915 RST RST GND
29156 TA10
RPU 10k
VCC P
RELATED PARTS
PART NUMBER LTC690 LTC694-3.3 LTC1232 LTC1326 LTC1726 LTC1727 LTC1728 LTC1985-1.8 LTC2900 LTC2901 LTC2902 LTC2903 LTC2904/LTC2905 LTC2906 LTC2907 LTC2908 LTC2909 LTC2910 LTC2912 LTC2913 LTC2914 DESCRIPTION 5V Supply Monitor, Watchdog Timer and Battery Backup 3.3V Supply Monitor, Watchdog Timer and Battery Backup 5V Supply Monitor, Watchdog Timer and Push-Button Reset Micro Power Precision Triple Supply Monitor Micro Power Triple Supply Monitor with Open-Drain Reset Micro Power Triple Supply Monitor with Open-Drain Reset Micro Power Triple Supply Monitor with Push-Pull Reset Programmable Quad Supply Monitor Programmable Quad Supply Monitor Programmable Quad Supply Monitor Precision Quad Supply Monitor 3-State Programmable Precision Dual Supply Monitor Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Precision Six Supply Monitor (Four Fixed and 2 Adjustable) Precision Triple/Dual Input UV, OV Monitor Octal Positive/Negative Voltage Monitor Single UV/OV Voltage Monitor, Adjustable UV and OV Trip Values Dual UV/OV Voltage Monitor Qual UV/OV Positive/Negative Voltage Monitor COMMENTS 4.65V Threshold 2.9V Threshold 4.37V/4.62V Threshold 4.725V, 2.363V, 3.118V, 1V Threshold (0.75%) Individual Monitor Outputs in MSOP 5-Lead SOT-23 Package 5-Lead SOT-23 Package Adjustable RESET, 10-Lead MSOP and 3mm x 3mm 10-Lead DFN Adjustable RESET and Watchdog Timer, 16-Lead SSOP Package Adjustable RESET and Tolerance, 16-Lead SSOP Package, Margining 6-Lead SOT-23 Package, Ultra Low Voltage Reset Adjustable RESET and Tolerance, 8-Lead SOT-23 Package Separate VCC Pin, RST/RST Outputs Separate VCC Pin, Adjustable Reset Timer 8-Lead SOT-23 and DDB Packages 2 ADJ Inputs, Monitors Negative Voltages 16-Lead SSOP and 5mm x 3mm DFN Packages 8-Lead TSOT and 3mm x 2mm DFN Packages 10-Lead MOSP and 3mm x 3mm DFN Packages 16-Lead SSOP and 5mm x 3mm DFN Packages
Micro Power Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ Adjustable RESET and Watchdog Time-Outs
29156fa
12 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0108 REV A * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2007

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