ADIN2111CCPZ-R7 datasheet(33/125 Pages) AD

33 / 125 page

Data Sheet

ADIN2111

APPLICATIONS INFORMATION

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Rev. 0 | 33 of 125

Transistor Controlled LED

Figure 18 displays a typical configuration where the LED current

required is higher than what the Px_LED_0 and Px_LED_1 pins

can supply. The circuit operates using the active high LED mode.

An external transistor, such as an N channel metal-oxide semicon-

ductor field effect transistor (MOSFET), can be used. The transistor

must be selected so that the gate input capacitance is not sinking

current above the maximum rating of the Px_LED_x pin during

the actuation. Refer to the transistor technical specifications for

information. If required, the inrush current can be reduced by

placing a resistance between the transistor gate and the ADIN2111

pin, and/or adding a parallel capacitor between the GND and the

Px_LED_x pin. The additional resistor and capacitor values must be

defined based on the transistor selection.

Select the R0 and R1 resistors to control the LED current (refer to

the selected LED and transistor specifications of the manufacturer

for information).

External pull-down resistors (RPD0 and RPD1) with a value of 4.7 kΩ

are recommended. In Figure 18, VCC is the power supply used to

supply the LEDs.

Figure 18. Transistor Controlled LED Configuration

Autosense Polarity

In autosense mode, the polarity of the LED is automatically detect-

ed during power-up, hardware reset, or software reset. LED_0

(internal pull-up) and LED_1 (internal pull-down) have different

autosense behaviors due to their internal pull-up and pull-down

configurations. Use one of the configurations described in the

Active High LED Polarity, Active Low LED Polarity, and Transistor

Controlled LED sections so that the two LEDs can be controlled the

same way.

COMPONENT RECOMMENDATIONS

Crystal

The typical connection for an external crystal (XTAL) is shown

in Figure 19. To ensure minimum current consumption and to min-

imize stray capacitances, make connections between the crystal,

capacitors, and ground as close to the ADIN2111 as possible. Con-

sult individual crystal vendors for recommended load information

and crystal performance specifications.

The crystal specification defines CL. CPCB1 and CPCB2 are the

parasitic impedances of the PCB between XTAL_I/CLK_IN and

ground, and between XTAL_O and ground, respectively. CX1 is the

capacitor connected to XTAL_I/CLK_IN, and CX2 is the capacitor

connected to XTAL_O.

Assuming the following:

►

CPCB1 ≈ CPCB2 ≈ CPCBx

►

CX1 ≈ CX2 ≈ CXx

Then, CXx = 2 × CL – CPCBx – 3 pF

Choose precision capacitors for CXx with low appreciable tempera-

ture coefficients to minimize frequency errors.

To ensure minimum current consumption and to minimize stray ca-

pacitances, make the connections between the crystal, capacitors,

and ground as close to the ADIN2111 as possible.

ADIN2111

25MHz

CX1

CPCB2

CPCB1

Figure 19. Crystal Oscillator Connection

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