Data Sheet

ADL5309

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

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Rev. A | 6 of 25

Figure 3. Pin Configuration

Table 6. Pin Function Descriptions

Pin Number

Mnemonic

Description

A1, D1, B2, C2

SUM

Guard Pins. The SUM pins shield current lines to INP1 and INP2 and are internally connected together. Do not

ground.

B1

INP1

Channel 1 Photocurrent Input. Connected to the photodiode anode (current flows into INP1 pin).

C1

INP2

Channel 2 Photocurrent Input. Connected to the photodiode anode (current flows into INP2 pin).

A2

PDB1

Channel 1 Photodiode Bias. May be connected to the photodiode cathode to provide adaptive bias control. For

lowest photodiode cathode to anode offset at low input currents, avoid resistive loading at the PDB1 pin. Leave

floating if not used.

D2

PDB2

Channel 2 Photodiode Bias. May be connected to the photodiode cathode to provide adaptive bias control. For

lowest photodiode cathode to anode offset at low input currents, avoid resistive loading at the PDB2 pin. Leave

floating if not used.

A3

VCC

Positive Power Supply. Decoupling with 1 nF and 4.7 μF capacitors to ground is recommended at the VCC pin.

B3, C3, B4, C4

GND

Analog and Digital Ground. Connect all ground pins to a low impedance ground plane on PCB.

D3

CAP

Connect an optional 0.1 µF capacitor between the CAP pin and GND to reduce the OUT1 and/or OUT2 noise at low

input currents.

D4

ADCREF

ADC Reference. Reference voltage input for improved ADC readout accuracy. Connect to ground if not used.

A4

SBA

Serial Bus Address. The voltage applied to the SBA pin sets the I2C bus address to one of three possible settings.

Connect SBA to VCC, GND, or leave floating. Refer to Table 1.

A5

OUT1

Channel 1 Logarithmic Output. The voltage at the OUT1 pin changes logarithmically with the current applied to

INP1.

D5

OUT2

Channel 2 Logarithmic Output. The voltage at the OUT2 pin changes logarithmically with the current applied to

INP2.

B5

SDA

I2C Interface Data Input and Output.

C5

SCL

I2C Interface Clock Input.