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TC1072-36VCH Folha de dados(PDF) 6 Page - Microchip Technology |
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TC1072-36VCH Folha de dados(HTML) 6 Page - Microchip Technology |
6 / 20 page TC1072/TC1073 DS21354B-page 6 © 2002 Microchip Technology Inc. 3.0 DETAILED DESCRIPTION The TC1072 and TC1073 are precision fixed output voltage regulators. (If an adjustable version is desired, please see the TC1070/TC1071/TC1187 data sheet.) Unlike bipolar regulators, the TC1072 and TC1073’s supply current does not increase with load current. In addition, VOUT remains stable and within regulation over the entire 0mA to IOUTMAX load current range, (an important consideration in RTC and CMOS RAM battery back-up applications). Figure 3-1 shows a typical application circuit. The regulator is enabled any time the shutdown input (SHDN)isatorabove VIH, and shutdown (disabled) when SHDN is at or below VIL. SHDN may be controlled by a CMOS logic gate, or I/O port of a microcontroller. If the SHDN input is not required, it should be connected directly to the input supply. While in shutdown, supply current decreases to 0.05 µA (typical), VOUT falls to zero volts, and ERROR is open- circuited. FIGURE 3-1: TYPICAL APPLICATION CIRCUIT 3.1 ERROR Open Drain Output ERROR is driven low whenever VOUT falls out of regulation by more than – 5% (typical). This condition may be caused by low input voltage, output current limiting, or thermal limiting. The ERROR output voltage value (e.g. ERROR =VOL at 4.75V (typ.) for a 5.0V regulator and 2.85V (typ.) for a 3.0V regulator). ERROR output operation is shown in Figure 3-2. Note that ERROR is active when VOUT falls to VTH,and inactive when VOUT rises above VTH by VHYS. As shown in Figure 3-1, ERROR canbeusedasa battery low flag, or as a processor RESET signal (with the addition of timing capacitor C2). R1 x C2 should be chosen to maintain ERROR below VIH of the processor RESET input for at least 200 msec to allow time for the system to stabilize. Pull-up resistor R1 can be tied to VOUT,VIN or any other voltage less than (VIN +0.3V). FIGURE 3-2: ERROR OUTPUT OPERATION 3.2 Output Capacitor A1 µF(min) capacitor from VOUT to ground is recommended. The output capacitor should have an effective series resistance greater than 0.1 Ω and less than 5.0 Ω, and a resonant frequency above 1MHz. A 1 µF capacitor should be connected from VIN to GND if there is more than 10 inches of wire between the regulator and the AC filter capacitor, or if a battery is used as the power source. Aluminum electrolytic or tantalum capacitor types can be used. (Since many aluminum electrolytic capacitors freeze at approxi- mately -30°C, solid tantalums are recommended for applications operating below -25°C.) When operating from sources other than batteries, supply-noise rejection and transient response can be improved by increasing the value of the input and output capacitors and employing passive filtering techniques. 3.3 Bypass Input A 470pF capacitor connected from the Bypass input to ground reduces noise present on the internal reference, which in turn significantly reduces output noise. If output noise is not a concern, this input may be left unconnected. Larger capacitor values may be used, but results in a longer time period to rated output voltage when power is initially applied. TC1072 TC1073 VOUT SHDN GND ERROR 1 µF C1 + VIN VOUT Shutdown Control (to CMOS Logic or Tie to VIN if unused) 1 µF + Battery + 0.2 µF C2 C2 Required Only if ERROR is used as a Processor RESET Signal (See Text) R1 1M V+ BATTLOW or RESET Bypass C3, 470pF VTH VOUT ERROR VIH VOL HYSTERESIS (VH) |
Nº de peça semelhante - TC1072-36VCH |
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Descrição semelhante - TC1072-36VCH |
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