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SI2401FS10-EVB データシート(PDF) 5 Page - Silicon Laboratories |
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SI2401FS10-EVB データシート(HTML) 5 Page - Silicon Laboratories |
5 / 32 page Si2401FS10-EVB Rev. 1.1 5 3.1.1. Voltage Regulator/Power Supply The input voltage to either J3 or J4 must be between 7.5 and 13.5 V dc or 7.5 and 13.5 VPEAK ac. The motherboard includes a diode bridge (D1–D4) to guard against a polarity reversal of the dc voltage or to rectify an ac voltage. The power source must be capable of continuously supplying at least 100 mA. C50 serves as a filter cap for an ac input. The voltage regulator, U1, provides 5 V for the motherboard and the input for voltage regulator U2, which outputs 3.3 V for use on the motherboard and to power the daughter card. Si24xxDC power consumption can be measured by placing a meter between pins 1 and 2 of JP7. The connection between JP7 pins 1 and 2 must be made at all times when power is applied to the evaluation board either through a jumper block or a low-impedance meter to avoid damage to the daughter card. Power is supplied to U2 through D5 from the USB. 3.1.2. Reset Circuitry The Si2401 requires a reset pulse to remain low for at least 5.0 ms after the power supply has stabilized during the powerup sequence or for at least 5.0 ms during a power-on reset, then go high with a rise time <100 ns. Most production Si2401 modem chipset applications require that RESET be controlled by the host processor. Certain Si2401 operation modes, including Powerdown, require a hardware reset to recover. The Si2401FS10-EVB contains two reset options, an automatic power-on reset device, U3 (DS1818) (default), and a manual reset switch (S1) to permit resetting of the chip without removing power. Regardless of the mechanism, a reset causes all modem settings to revert to factory default values. See Figure 6 on page 11 and Figure 8 on page 13 for the reset circuit schematic. 3.1.3. DS1818 The DS1818 is a small, low-cost device that monitors the voltage on VD and an external reset pushbutton. If VD drops below 3.0 V, the DS1818 provides a 220 ms active-low reset pulse. On power-up, the DS1818 also outputs an active low reset pulse for 220 ms after VD reaches 90% of the nominal 3.3 V value. The DS1818 outputs a 220 ms reset pulse any time the power supply voltage exceeds the 3.3 V ±10% window. 3.1.4. Manual Reset The manual reset switch (S1) performs a power-on reset. This resets the Si2401 to factory defaults without turning off power. If S1 is used in conjunction with U6, pressing S1 activates the reset monitor in the DS1818 and produces a 220 ms active low reset pulse. 3.1.5. Interface Selection The serial interface of the Si2401FS10-EVB can be connected to a computer terminal, embedded system, or any other Data Terminal Equipment (DTE) via a standard RS-232 interface, USB interface, or direct TTL serial interface. The Si2401 can be tested as a standard data modem by connecting the Si2401FS10-EVB to a personal computer or other DTE, power supply, and a phone line. A PC can communicate with the Si2401FS10-EVB using a standard terminal program, such as HyperTerm or ProComm. Jumper settings determine how the Si2401FS10-EVB is connected to the DTE. Table 3 lists the interface controlled by each motherboard jumper. See Figure 7 on page 12 and Figure 17 on page 22. 3.1.6. RS-232 Interface This operation mode uses the standard factory jumper settings illustrated in Figure 1 on page 3. The Maxim MAX3237 transceiver interfaces directly with the TTL levels available at the serial interface of the Si2401 and, using internal charge pumps, makes these signals compatible with the RS-232 standard. The RS-232 transceiver on the Si2401FS10-EVB can communicate at rates between 300 bps and 1 Mbps. This simplifies the connection to PCs and other Data Terminal Equipment (DTE). The signals available on the Si2401FS10-EVB serial interface (DB9 connector) are listed in Table 4. Table 3. Interface Selection Jumpers Jumper Function JP1 Daughter Card Phone Line Connector. JP2 Daughter Card Digital Connector. JP3 Direct Access Header. JP4 Not Used. JP5 USB Enable (RS-232 Disable). JP6 Options. JP7 3.3 V Power for Daughter Card. JP8 Disable both RS-232 and USB. JP9 Not Used. JP10 Not Used. JP11 Not Used. JP12 Enable 27 MHz Clock Option. |
同様の部品番号 - SI2401FS10-EVB |
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同様の説明 - SI2401FS10-EVB |
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