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The TL77xxA family of integrated-circuit supply-voltage supervisors is designed specifically for use as reset controllers in microcomputer and microprocessor systems. The supply-voltage supervisor monitors the supply for undervoltage conditions at the SENSE input. During power up, the RESET output becomes active (low) when VCC attains a value approaching 3.6 V. At this point (assuming that SENSE is above VIT+), the delay timer function activates a time delay, after which outputs RESET and RESET go inactive (high and low, respectively). When an undervoltage condition occurs during normal operation, RESET and RESET go active.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
TL77xxA | SOIC (8) | 4.90 mm × 3.91 mm |
PDIP (8) | 9.81 mm × 6.35 mm | |
TL7705A | SO (8) | 6.20 mm × 5.30 mm |
Changes from J Revision (January 2015) to K Revision
Changes from I Revision (July 2009) to J Revision
PIN | TYPE | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
CT | 3 | I/O | External timing-capacitor pin |
GND | 4 | — | Device ground |
REF | 1 | O | Voltage reference output |
RESET | 6 | O | Supervisor reset signal output |
RESET | 5 | O | Supervisor reset signal output (inverted) |
RESIN | 2 | I | Reset input |
SENSE | 7 | I | Sense input |
VCC | 8 | — | Power Supply |
MIN | MAX | UNIT | |||
---|---|---|---|---|---|
VCC | Supply voltage(3) | 20 | V | ||
VI | Input voltage, RESIN | –0.3 | 20 | V | |
VI | Input voltage range SENSE | TL7702A(2) | –0.3 | 6 | V |
TL7705A | –0.3 | 20 | V | ||
TL7709A | –0.3 | 20 | V | ||
TL7712A, TL7715A | –0.3 | 20 | V | ||
IOH | High-level output current, IOH, RESET | –30 | mA | ||
IOL | Low-level output current, IOL, RESET | 30 | mA | ||
TJ | Operating virtual junction temperature | 150 | °C | ||
Tstg | Storage temperature | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | 1000 | V |
Charged device model (CDM), per JEDEC specification JESD22-C101(2) | 1000 |
MIN | MAX | UNIT | |||
---|---|---|---|---|---|
VCC | Supply Voltage | 3.5 | 18 | V | |
VIH | High-level input voltage at RESIN | 2 | V | ||
VIL | Low-level input voltage at RESIN | 0.6 | V | ||
VI | Input voltage, SENSE | TL7702A | 0 | See(1) | V |
TL7705A | 0 | 10 | |||
TL7709A | 0 | 15 | |||
TL7712A | 0 | 20 | |||
TL7715A | 0 | 20 | |||
IOH | High-level output current, RESET | –16 | mA | ||
IOL | Low-level output current, RESET | 16 | mA | ||
TA | Operating free-air temperature | TL77xxAC | 0 | 70 | °C |
TL77xxAI | –40 | 85 |
THERMAL METRIC(1) | TL77xxA | UNIT | |||
---|---|---|---|---|---|
D | P | PS | |||
8 PINS | 8 PINS | 8 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 97 | 85 | 95 | °C/W |
PARAMETER | TEST CONDITIONS(1) | TL77xxAC TL77xxAI |
UNIT | ||||||
---|---|---|---|---|---|---|---|---|---|
MIN | TYP | MAX | |||||||
VOH | High-level output voltage, RESET | IOH = –16 mA | VCC – 1.5 | V | |||||
VOL | Low-level output voltage, RESET | IOL = 16 mA | 0.4 | V | |||||
Vref | Reference Voltage | TA = 25°C | 2.48 | 2.53 | 2.58 | V | |||
VIT– | Negative-going input threshold voltage, SENSE | TL7702A | TA = 25°C | 2.48 | 2.53 | 2.58 | V | ||
TL7705A | 4.5 | 4.55 | 4.6 | ||||||
TL7709A | 7.5 | 7.6 | 7.7 | ||||||
TL7712A | 10.6 | 10.8 | 11 | ||||||
TL7715A | 13.2 | 13.5 | 13.8 | ||||||
Vhys | Hysteresis, SENS (VIT+ – VIT–) | TL7702A | TA = 25°C | 10 | mV | ||||
TL7705A | 15 | ||||||||
TL7709A | 20 | ||||||||
TL7712A | 35 | ||||||||
TL7715A | 45 | ||||||||
II | Input current | RESIN | VI = 2.4 V to VCC | 20 | µA | ||||
VI = 0.4 V | –100 | ||||||||
SENSE | TL7702A | Vref < VI < VCC – 1.5 V | 0.5 | 2 | |||||
IOH | High-level output current, RESET | VO = 18 V | 50 | µA | |||||
IOL | Low-level output current, RESET | VO = 0 | –50 | µA | |||||
ICC | Supply current | All inputs and outputs open | 1.8 | 3 | mA |
PARAMETER | TEST CONDITIONS(1) | TL77xxAC TL77xxAI |
UNIT | ||||
---|---|---|---|---|---|---|---|
MIN | TYP | MAX | |||||
Output pulse duration | CT = 0.1 µF | 0.65 | 1.2 | 2.6 | msec | ||
Input pulse duration at RESIN | 0.4 | µs | |||||
tw(S) | Pulse duration at sense input to switch outputs | VIH = VIT− + 200 mV, VIL = VIT− − 200 mV | 2 | µs | |||
tpd | propagation delay time, RESIN to RESET | VCC = 5V | 1 | µs | |||
tr | Rise time | RESET | VCC = 5 V(2) | 0.2 | µs | ||
RESET | 3.5 | ||||||
tf | Fall time | RESET | VCC = 5 V(2) | 3.5 | µs | ||
RESET | 0.2 |
The TL77xxA family of integrated-circuit supply-voltage supervisors is designed specifically for use as reset controllers in microcomputer and microprocessor systems. The supply-voltage supervisor monitors the supply for undervoltage conditions at the SENSE input. During power up, the RESET output becomes active (low) when VCC attains a value approaching 3.6 V. At this point (assuming that SENSE is above VIT+), the delay timer function activates a time delay, after which outputs RESET and RESET go inactive (high and low, respectively). When an undervoltage condition occurs during normal operation, RESET and RESET go active. To ensure that a complete reset occurs, the reset outputs remain active for a time delay after the voltage at the SENSE input exceeds the positive-going threshold value.
During power down and when SENSE is below VIT−, the outputs remain active until VCC falls below 2 V. After this, the outputs are undefined. An external capacitor (typically 0.1 μF) must be connected to REF to reduce the influence of fast transients in the supply voltage.
Five versions of this circuit are available:
The functional block diagram is shown for illustrative purposes only; the actual circuit includes a trimming network to adjust the reference voltage and sense-comparator trip point.
Th TL77xxA family operates of a wide supply voltage range of 3.5 V to 18 V.
The time delay is determined by the value of the external capacitor CT: td = 1.3 × 104 × CT, where CT is in farads (F) and td is in seconds (s).
The series TL77xxA incorporates an extremely stable reference voltage source. This voltage source can also be used in applications where a constant voltage source is required. The reference voltage varies less than 10 mV over the supply voltage range of 3.5 V to 18 V. The same stability of the reference voltage is maintained, when the ambient temperature is changed. The reference's voltage varies only 16 mV when the ambient temperature is changed from –40°C to +85°C.
Figure 7 shows the timing of the various signals. In this example the SENSE input is connected to the supply voltage VCC as in typical applications of this device. The minimum supply voltage for which the function of this device is guaranteed is 3.6 V. After power-on, the outputs are undefined until the minimum supply voltage Vres is reached. For the TL77xxA the minimum supply voltage is Vres = 3 V (typical 2.5 V). Beyond the voltage Vres the capacitor CT is first kept discharged, and the outputs stay in the active state (RESET = High, RESET = Low). When the input voltage becomes higher than the threshold voltage Vt, the thyristor is turned off and the capacitor is charged. After a delay, td, the voltage at the capacitor passes the trigger level of the output comparator and the outputs become inactive. The circuit to be initialized is now set to a defined state and starts the correct operation.
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
This application shows the initialization circuit diagrams for a microprocessor system with supply voltage Vcc = 5 V. The external components required are the decoupling capacitor Cref for the reference voltage and the timing capacitor CT. The outputs of the TL77xxA are open collector outputs. In Figure 8 therefore a pull-up resistor is shown at the RESET output to ensure the correct HIGH level.
The TL77xxA devices operate within the specifications from the Recommended Operating Conditions between 3.5 V and 18 V.
CAUTION
These devices risk being damaged when powered by more than 20 V.
The voltage monitor should be placed on the printed circuit board, where there are no neighboring circuits in the which switch high currents (like bus interface circuits and power switches). When laying out the layout of the printed circuit board, take special care with the interconnects which carry analog signals. Beside the SENSE input these are the CT and Vref terminals. Noise coupled into the CT input will lead to a reduction of the output pulse width. Noise coupled into the Vref input or into the filter capacitor at this input may lead to undesired triggering of the circuit and by this to an undesired RESET pulse. Practice shows, that this malfunction when high currents flow over the interconnects of these capacitors to the GND terminal of the voltage monitor. To avoid these effects, the GND terminals of these capacitors must be connected by the shortest way to the GND terminal of the voltage monitor in so that no currents caused by other circuits flow over these wires. Figure 16 show a layout proposal for the printed circuit board. Furthermore the resistors of the voltage divider at the SENSE input of the TL7702 (R2 and R3 in Figure 16) have to be placed in so, that no noise may be coupled into this circuit.
The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy.
PARTS | PRODUCT FOLDER | SAMPLE & BUY | TECHNICAL DOCUMENTS | TOOLS & SOFTWARE | SUPPORT & COMMUNITY |
---|---|---|---|---|---|
TL7702A | Click here | Click here | Click here | Click here | Click here |
TL7705A | Click here | Click here | Click here | Click here | Click here |
TL7709A | Click here | Click here | Click here | Click here | Click here |
TL7712A | Click here | Click here | Click here | Click here | Click here |
TL7715A | Click here | Click here | Click here | Click here | Click here |
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This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
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