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Texas Instruments · Integrated circuit

ADS1115 16-Bit ADC

Four single-ended or two differential channels at 16 bits over I2C, with a gain stage and its own reference. What you add when the microcontroller's ADC is not good enough.

Cheat sheet (SVG)
Logic level
2-5.5 V
Package
VSSOP-10 (DGS) / X2QFN-10 / WCSP

1.Pinout diagram

Highlight a signalhover to preview, click to keep

Pins 1-5

ADS1115

Pins 6-10

Pin detail

Hover a pin for its mappings and gotchas. Click to keep it here.

Logic level
2-5.5 V
Package
VSSOP-10 (DGS) / X2QFN-10 / WCSP

Fig. 1. ADS1115 16-Bit ADC, VSSOP-10 (DGS). Hover or tap a signal to light up every pin that carries it.

2.Watch out

  • The full-scale range is not an input rating. Selecting +/-6.144 V on a 3.3 V supply does not let you measure 6 V: the datasheet is explicit that no more than VDD + 0.3 V may reach an analog input. The wide ranges exist so the gain stage can be set below the supply, not above it. This is the mistake that kills these chips.
  • ADDR goes to GND, VDD, SDA or SCL, giving 0x48 through 0x4B. If you use SDA as the address, hold SDA low for at least 100 ns after SCL falls or the device may decode it wrong.
  • Eight data rates from 8 to 860 samples per second. Slow is not wasted: the lower rates integrate longer and are quieter, and 8 SPS is where the 16 bits actually mean something.
  • Four single-ended channels or two differential pairs, not both at once. Differential is the reason to buy this part, because it rejects the common-mode noise that a single-ended reading has no way to see.
  • The reference is internal, so readings do not drift with a noisy supply the way a microcontroller ADC referenced to its own 3.3 V rail does.
  • ALERT/RDY is open drain and needs a pull-up. It doubles as a conversion-ready strobe, which saves polling the config register in continuous mode.
  • The ADS1015 is the same chip at 12 bits and 3300 SPS, pin compatible and register compatible. Code written for one runs on the other with the result shifted four bits.

3.Minimum circuit

What has to go around the chip before it will run.

VCCGNDADS11150.1 uF ceramic between VDD (8) and GND0.1 uFceramic4.7 kOhm between SDA (9) and VCC4.7 kOhm4.7 kOhm between SCL (10) and VCC4.7 kOhmAddress link between ADDR (1) and GNDAddresslink10 kOhm between ALERT/RDY (2) and VCC10 kOhmGND (3) to GNDVDD (8) to VCCADDR 1ALERT/RDY 2GND 3VDD 8VDD 8SDA 9SCL 10
Fig. 2. Minimum circuit, drawn from Table 1. Dashed parts are optional. Crossing wires are not connected.
Table 1. External parts, and why each one is there.
PartBetween
0.1 uF ceramicVDD (8) to GND
4.7 kOhmSDA (9) to VCC
4.7 kOhmSCL (10) to VCC
Address linkADDR (1) to GND
10 kOhmoptionalALERT/RDY (2) to VCC

Unused analog inputs should be tied to GND rather than left floating. A high-impedance source wants a capacitor across the input to supply the charge the sampling network takes.

4.Full pin reference

Every pin, alias and mapping. This is the table that prints.

Table 2. Pin assignments.

Complete pin reference for ADS1115 16-Bit ADC
PinNameFunctions

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Primary sources

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