ADuCM4050

Data Sheet

Rev. A | Page 12 of 46

SYSTEM CLOCKS

External Crystal Oscillator Specifications

Table 10.

Parameter

Symbol

Min

Typ

Max

Unit

Test Conditions/Comments

LOW FREQUENCY EXTERNAL CRYSTAL

OSCILLATOR (LFXTAL)

Frequency

32,768

Hz

External Capacitance from

SYS_LFXTAL_IN Pin to Ground and

from SYS_LFXTAL_OUT Pin to Ground

6

10

pF

External capacitors on SYS_LFXTAL_IN

and SYS_LFXTAL_OUT pins must be

selected considering the printed circuit

board (PCB) trace capacitance due to

routing

Crystal Equivalent Series Resistance

30

50

kΩ

50

nW

8

µS

HIGH FREQUENCY EXTERNAL CRYSTAL

OSCILLATOR (HFXTAL)

Frequency

26

MHz

External Capacitance from

SYS_HFXTAL_IN Pin to Ground and

from SYS_HFXTAL_OUT Pin to Ground

20

pF

External capacitors on SYS_HFXTAL_IN

and SYS_HFXTAL_OUT pins must be

selected considering the PCB trace

capacitance due to routing

Crystal Equivalent Series Resistance

50

Ω

1

Guaranteed by design.

On-Chip Resistor-Capacitor (RC) Oscillator Specifications

Table 11.

Parameter

Symbol

Min

Typ

Max

Unit

LOW FREQUENCY RC OSCILLATOR (LFOSC)

Frequency

30,800

32,768

35,062

Hz

HIGH FREQUENCY RC OSCILLATOR (HFOSC)

Frequency

25.03

26

27.07

MHz

System Clocks and Phase-Locked Loop (PLL) Specifications

Table 12.

Parameter

Symbol

Min

Typ

Max

Unit

PLL SPECIFICATIONS

16

26

MHz

16

60

MHz

System Peripheral Clock (PCLK) Frequency

0.8125

52

MHz

Advanced High Performance Bus Clock (HCLK) Frequency

0.8125

52

MHz

1

The input to the PLL can come from either the high frequency external crystal (HFXTAL), SYS_CLKIN pin or from the high frequency internal RC oscillator (HFOSC).

2

For the maximum value, the recommended settings are PLL MSEL = 13, PLL NSEL = 16, PLL DIV2 = 1 for PLL input clock = 26 MHz; and PLL MSEL = 13, PLL NSEL = 26,

PLL DIV2 = 1 for PLL input clock = 16 MHz; see the ADuCM4050 Ultra Low Power ARM Cortex-M4F MCU with Integrated Power Management Hardware Reference for

more information on these configuration options.

3

For the minimum value, the recommended settings are PLL MSEL = 13, PLL NSEL = 30, PLL DIV2 = 0 for PLL input clock = 26 MHz; and PLL MSEL = 8, PLL NSEL = 30,

PLL DIV2 = 0 for 16 MHz.