ADIN1101CCPZ-R7 datasheet(35/79 Pages) AD

35 / 79 page

Data Sheet

ADIN1101

APPLICATIONS INFORMATION

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Rev. A | 35 of 79

LED CIRCUIT EXAMPLES

The LED_0 pin can be used in various circuit configurations de-

pending on the LED polarity mode selected (see the LED Polarity

provide examples for three polarity modes that are available for

each LED. Three polarity modes are available for the LED, as

follows:

►

Autosense (default)

►

Active high

►

Active low

The output current for the LED_0 pin is 8 mA with a VDDIO =

3.3 V (see the Specifications section for details). For higher current

requirements, consider using the circuit described in the Transistor

Controlled LED section.

Active High LED Polarity

In active high configuration, the LED_0 pin can drive an external

LED from the anode side. Select the R0 resistor to control the LED

current (refer to the LED specifications in Table 1 for information).

An external pull-down resistor (RPD0) with a value of 4.7 kΩ is

recommended.

Figure 25. Active High LED Polarity Configuration

Active Low LED Polarity

In active low configuration, the LED_0 pin can drive an external

LED from the cathode side. Select the R0 resistor to control the

LED current (refer to the LED specifications in Table 1 for informa-

tion). An external pull-up resistor (RPU0) with a value of 4.7 kΩ is

recommended.

Figure 26. Active Low LED Polarity Configuration

Transistor Controlled LED

Figure 27 displays a typical configuration where the LED current

required is higher than what the LED_0 pin can supply. The circuit

operates using the active high LED mode. An external transistor

such as an N channel metal-oxide semiconductor field effect tran-

sistor (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 LED_0 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 ADIN1101 pin and/or adding a parallel

capacitor between GND and the LED_0 pin. The additional resistor

and capacitor values must be defined based on the transistor

selection.

Select the R0 resistor to control the LED current (refer to the

selected LED and transistor specifications of the manufacturer for

information).

An external pull-down resistor (RPD0) with a value of 4.7 kΩ is

recommended. In Figure 27, VCC is the power supply used to

supply the LEDs.

Figure 27. 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.

COMPONENT RECOMMENDATIONS

The ADIN1101 requires an external 25 MHz or 50 MHz clock, which

can be sourced from an external crystal oscillator (25 MHz) or an

external single-ended clock (25 MHz or 50 MHz). The RMII requires

an external 50 MHz clock as described in the External 50 MHz

Clock Input for RMII Mode section.

The signal voltage on the XTAL_I/CLK_IN pin (VCLK_IN) must be

a sine or filtered square wave signal with a peak-to-peak voltage

range from 0.8 V to 2.5 V. For the single-ended clock option, a

VCLK_IN with a 1.0 V p-p swing is recommended to achieve best

performance.

Various circuit configurations are proposed in the following sections.

A common circuit topology can be used across these options with a

change to the passive component values.

Note that during normal operation, a 25 MHz reference clock

generated from the external clock source input (crystal, 25 MHz or

50 MHz clock) is provided on the CLK25_REF output pin. This pin

can be used as a reference clock for other circuits, such as another

10BASE-T1L device. CLK25_REF is disabled in reset mode.

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