LMX9820ASM datasheet(5/44 Pages) NSC

5 / 44 page

Revision 1.0

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5.0 Pad Descriptions

Table 2. System Interface Signals

Pad Name

Pad

Location

Direction

Description

Clk-

Input

Xtal g or Negative Clock Input. Typically connected along with

XTAL_D to an external surface-mount AT-cut crystal. Leave not con-

nected in case Clk+ is connected to external crystal oscillator.

Clk+

Input

Xtal d or Positive Clock Input. Typically connected along with

XTAL_G to an external surface-mount AT-cut crystal. Can also be con-

figured as a frequency input when using an external crystal oscillator.

When configured as a frequency input, typically connected to an exter-

nal Temperature Compensated Crystal Oscillator (TCXO) through an

Alternating Current (AC) coupling capacitor.

32kHz_CLKI

B13

Input

32 kHz Clock input. Not supported by LMX9820A. Connect to ground.

Pad required for mechanical stability.

32kHz_CLKO

C13

Output

32 kHz Clock Output. Not supported by LMX9820A. Treat as no con-

nect. Pad required for mechanical stability.

RF_inout

Input/Output

RF Antenna Port. 50

Ω nominal impedance. Typically connected to an

antenna through a 6.8 pF capacitor.

ISEL2

H13

Input

Module Interface Select Input Bit 1

ISEL1

J13

Input

Module Interface Select Input Bit 0

Table 3. USB Interface Signals (not supported by LMX9820A firmware)

Pad Name

Pad

Location

Direction

Description

USB_VCC

F12

Input

USB Transceiver Power Supply + 1

USB_D+

E11

Input/Output

USB Data Positive 1

USB_D-

E12

Input/Output

USB Data Negative 1

USB_Gnd

G12

Input

USB Transceiver Ground. Connect to GND.

Treat as no connect. Pad required for mechanical stability.

Table 4. UART Interface Signals

Pad Name

Pad

Location

Direction

Description

Uart_tx

Output

UART Host Control Interface Transport, Transmit Data

Uart_rx

Input

UART Host Control Interface Transport, Receive Data

Uart_rts#

C10

Output

UART Host Control Interface Transport, Request to Send 1

Uart_cts#

D10

Input

UART Host Control Interface Transport, Clear to Send 2

Treat as no connect if not used. Pad required for mechanical stability.

Connect GND if not used.

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