Datenblatt-Suchmaschine für elektronische Bauteile |
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ADM1051 Datenblatt(PDF) 7 Page - Analog Devices |
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ADM1051 Datenblatt(HTML) 7 Page - Analog Devices |
7 / 10 page REV. 0 ADM1051/ADM1051A –7– For compatibility with the TYPEDET signal, the regulator output voltage of Channel 1 may be selected using the Shutdown pin. This is a multilevel, dual-function input that allows selection of the regulator output voltage as well as shutdown of the regulator. By setting SHDN1 to different voltages, the regulator can be put into four different operating modes. Table I. Shutdown Functionality for 1.5 V Channel SHDN1 Voltage Mode Function < 0.8 V 1 Force Output Low, Regulator Shutdown 2 V–3.9 V 2 1.5 V Output 4.3 V–5.3 V 3 Force Output High, VOUT = 3.3 V >6.2 V or Floating 4 1.5 V Output If the SHDN1 pin is connected to a voltage less than 0.8 V, the FORCE output will go low and the regulator will be shut down. If the SHDN1 pin is connected to a voltage greater than 6.2 V, or simply left open-circuit, the regulator will operate normally and provide 1.5 V out. This allows the regulator to operate normally with no external connection to SHDN1. If the SHDN1 pin is connected to a voltage between 2 V and 3.9 V, the regulator will also operate normally and provide 1.5 V out. If the SHDN1 pin is connected to a voltage between 4.3 V and 5.3 V, the FORCE output will be high and the external MOSFET will be turned hard on, making the output voltage equal to the 3.3 V input (less any small drop due to the on-resistance of the MOSFET). In this mode it is not actually regulating, but simply acting as a switch for the 3.3 V supply. The voltage drop across the Channel 1 MOSFET in Mode 3 can be minimized by using a MOSFET with very low on resistance, for which Channel 1 is optimized, such as the PHD55N03LT. The latter two modes allow the regulator to be controlled by the TYPEDET signal simply by using potential divider, as shown in Figure 2. TYPEDET SHDN1 PC 5V SUPPLY 3k 3k Figure 2. Using SHDN1 with TYPEDET Signal A shutdown function can be added by connecting an open-drain/ open-collector logic output to SHDN1, or by using a totem-pole logic output with a Schottky diode, as shown in Figure 3. ADM1051/ ADM1051A OPEN-DRAIN OR OPEN-COLLECTOR OUTPUT TYPEDET SHDN1 PC 5V SUPPLY 3k 3k EN TYPEDET ADM1051/ ADM1051A SHDN1 PC 5V SUPPLY 3k 3k SCHOTTKY DIODE COMPLEMENTARY OR TOTEM-POLE OUTPUT EN Figure 3. TYPEDET Voltage Selection Combined with Shutdown Function When the logic output is high or turned off, the regulator mode will be controlled by TYPEDET. When the logic output is low, the regulator will be shut down. Table II. TYPEDET and Shutdown Truth Table TYPEDET EN Regulator Mode X 0 Shutdown 0 1 1.5 V 1 1 3.3 V X = Don’t care. Note that when Channel 1 of the ADM1051 is set to 3.3 V, Channel 2 should not be shut down while Channel 1 is active. 12V SUPPLY VREF TURN-ON THRESHOLD POR THRESHOLD 4V – 7V GATE DRIVE TO EXTERNAL MOSFET MOSFET GATE THRESHOLD 3.3V SUPPLY TO EXTERNAL MOSFET DRAIN CHANNEL 1 OR CHANNEL 2 OUTPUT VOLTAGE NORMAL OUTPUT VOLTAGE FAULT REMOVED OUTPUT < 0.8 VREG CHANNEL 1 OR CHANNEL 2 OUTPUT CURRENT HICCUP MODE HOLD-OFF TIME 2 AMPS DEVICE ENTERS HICCUP MODE FAULT CURRENT 1:40 DUTY CYCLE OFF ON Figure 4. Power-On Reset and Hiccup Mode |
Ähnliche Teilenummer - ADM1051 |
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Ähnliche Beschreibung - ADM1051 |
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