ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

Rev. 6, August 2000

Page 7 of 18

1.7.1 Interface Description

Wake-up sequence:

TX/ASK=H, STDBY=H: Standby. All off low current state.

TX/ASK

→ L, STDBY=H; → XTAL oscillator starts up. NRES goes L, resetting (starting)

NRES returns to H, µC initializes.

After µC is initialized, it sets STDBY

→ L; PLL is turned on, after t

is generated.

TX/ASK

→ H, STDBY=L; → TX is turned on, t

can be transmitted.

To switch the AS3901 „on“a „push button“with series resistance ~10-20 k

Ω can be

used to make TX/ASK = „L“. The „push-button“must be pushed long enough (typ. >

3ms) for the µC to reset and sustain the TX/ASK „L“state.

Standby procedure (for sleep-mode ( IDD1 <1µA):

The µC outputs a „H“to TX/ASK and STDBY. After minimal 3 CLK cycles the XTAL

oscillator will be switched off. The pull-up resistors at the AS3901 TX/ASK and STDBY

inputs will sustain the sleep mode.

Note: Multiple „push buttons“for different functions can be used.