# External 32KHz Crystal Oscillator (XOSC32K) Characteristics

## Digital Clock Characteristics

The following table describes the characteristics for the oscillator when a digital clock is applied on XIN32 pin.

Table 1. Digital Clock Characteristics(1)
Symbol Parameter Min. Typ. Max. Units
fCPXIN32 XIN32 clock frequency   32.768 1000 kHz
DCXIN XIN32 clock duty cycle 40 50 60 %
Note:
1. 1.These values are based on simulation. They are not covered by production test limits or characterization.

## Crystal Oscillator Characteristics

The following section describes the characteristics for the oscillator when a crystal is connected between XIN32 and XOUT32 pins.

Figure 1. Oscillator Crystal Connection

The user must choose a crystal oscillator where the crystal load capacitance CL is within the range given in the table. The exact value of CL can be found in the crystal data sheet. The capacitance of the external capacitors (CLEXT) can then be computed as follows:

CLEXT = 2(CL - CPARA - CPCB - CSHUNT)

Where:

• CPARA is the internal load capacitor parasitic between XIN and XOUT ( CPARA = (CXIN32K CXOUT32K)/(CXIN32K + CXOUT32K) )
• CPCB is the capacitance of the PCB
• CSHUNT is the shunt capacity of the crystal.
Table 2. 32 KHz Crystal Oscillator Electrical Characteristics
Symbol Parameter Conditions Min. Typ. Max. Units
FOUT Crystal oscillator frequency - - 32.768 - kHz
CL(1) Crystal load capacitance - 7 - 9 pF
CSHUNT(1) Crystal shunt capacitance - 0.6 - 2 pF
CM(1) Motional capacitance - 0.6 - 3 fF
ESR(2) Crystal Equivalent Series Resistance - SF=3

f=32.768kHz,
CL= 9pF

- - 70
CXIN32k(2) Parasitic load capacitor - - 3.2 - pF
CXOUT32k(2) - - 3.4 -
tSTARTUP(2) Startup time

f=32.768kHz,
CL= 9pF

- 10 43 KCycles
Pon(1) Drive Level - - - 0.1 µW
Notes:
1. 1.These values are based on simulation. They are not covered by production test limits or characterization.
2. 2.These values are based on characterization. They are not covered in test limits in production.
Table 3. Power Consumption (1)
Symbol Parameter Conditions Ta Min. Typ. Max. Units
IDD Current consumption VCC=3.3V Max 85°C

Typ 25°C

- 309 606 nA
Note:
1. 1.These values are based on characterization. They are not covered in test limits in production.