SPI/Microwire-Compatible

UART in QSOP-16

14

______________________________________________________________________________________

MAX3100

CS

SCLK

DIN

DOUT

TX

RX

+5V

ISO +5V

+5V

GND

MAX3100

CS

SCLK

DIN

DOUT

RX

470

Ω

470

Ω

2k

2k

TX

GND

Figure 8. Bidirectional Opto-Isolated Interface

Table 8. Component and Supplier List

This oscillator supports parallel-resonant mode crystals

and ceramic resonators, or can be driven from an

external clock source. Internally, the oscillator consists

of an inverting amplifier with its input, X1, tied to its out-

put, X2, by a bias network that self-biases the inverter

usually a crystal, from X2 to X1 provides 180° of phase

shift, causing the circuit to oscillate. As shown in the

standard application circuit, the crystal or resonator is

connected between X1 and X2, with the load capaci-

tance for the crystal being the series combination of C1

and C2. For example, a 1.8432MHz crystal with a spec-

ified load capacitance of 11pF would use capacitors of

22pF on either side of the crystal to ground. Series-res-

onant mode crystals have a slight frequency error, typi-

cally oscillating 0.03% higher than specified series-

resonant frequency, when operated in parallel mode.

It is very important to keep crystal, resonator, and

load-capacitor leads and traces as short and direct as

possible. The X1 and X2 trace lengths and ground

tracks should be tight, with no other intervening traces.

This helps minimize parasitic capacitance and noise

pickup in the oscillator, and reduces EMI. Minimize

capacitive loading on X2 to minimize supply current.

Murata North America

ECS International, Inc.

SUPPLIER

CSA1.84MG

ECS-18-13-1

PART

NUMBER

(800) 831-9172

(913) 782-7787

PHONE

NUMBER

DESCRIPTION

1.8432

Through-Hole

Resonator

1.8432

Through-Hole Crystal

(HC-49/U)

FREQUENCY

(MHz)

47

25

TYPICAL

C1, C2 (pF)

ECS International, Inc.

ECS International, Inc.

ECS-36-20-5P

ECS-36-18-4

(913) 782-7787

(913) 782-7787

3.6864

SMT Crystal

3.6864

Through-Hole Crystal

(HC-49/US)

39

33

AVX/Kyocera

PBRC-3.68B

(803) 448-9411

3.6864

SMT Resonator

None

(integral)