# 74HC595 2-digit 7-segment display: specs

> A 2-digit, 7-segment LED display module that uses 74HC595 shift registers to drive the segments from a serial input. The values below describe the…

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A 2-digit, 7-segment LED display module that uses 74HC595 shift registers to drive the segments from a serial input. The values below describe the SN74HC595 chip; the module board, its header and its segment resistors are not covered by an official document.

Every value cites its sourcePinout not published

[Buy on Compoden](https://compoden.com/products/74hc595-2-digit-0-5-inch-7-segment-display-module)

## Specs

| Spec | Value | Source |
|---|---|---|
| SN74HC595 supply voltage (VCC) | 2 V to 6 V recommended (5 V nominal) | source 6.3 Recommended Operating Conditions |
| SN74HC595 absolute maximum VCC | 7 V | source 6.1 Absolute Maximum Ratings |
| SN74HC595 high-level input voltage (VIH) | 3.15 V min at VCC = 4.5 V | source 6.3 Recommended Operating Conditions |
| SN74HC595 output drive | +/-6 mA at 5 V (feature line); continuous output current +/-35 mA absolute maximum | source Features (p.1); 6.1 Absolute Maximum Ratings |
| SN74HC595 register | 8-bit serial-in, parallel-out shift register with 3-state output register | source Features (p.1); Description |
| SN74HC595 operating temperature | -40 to 85 C (SN74HC595) | source 6.3 Recommended Operating Conditions |

## Power

| | Value | Source |
|---|---|---|
| Supply | Chip: 2-6 V VCC (module supply not documented) | source Features (p.1) |
| Current | Chip supply current 80 uA max (LED current is extra) | source Features (p.1) |

## Pinout
We don't publish a pin table for this part: no official source we could verify gives one. Check the labels printed on your module, and see the notes below.

The chip pin names (SER, SRCLK, RCLK, OE, SRCLR, QA-QH, QH') are not listed as pin rows because the module's header labels, and which of them are brought out, are not documented. Check the printed labels on the board.

## Build with it
Project ideas for the 74HC595 2-digit 7-segment display. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

- [Two-digit counter](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20two-digit%20counter%20with%20an%20Arduino%20Uno%2C%20a%2074HC595%207-segment%20display%20and%20a%20push%20button): The Uno 5 V logic suits a 5 V module. Match the module's printed pin labels to your code.
- [Temperature in whole degrees](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20two-digit%20temperature%20display%20with%20an%20Arduino%20Nano%2C%20a%2074HC595%207-segment%20display%20and%20a%20DS18B20%20sensor): Two digits cover whole degrees; the Nano drives the shift registers from three pins.
- [Dial readout](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20two-digit%20readout%20of%20a%20dial%20position%20from%200%20to%2099%20with%20an%20Arduino%20Uno%2C%20a%20rotary%20potentiometer%20and%20a%2074HC595%207-segment%20display): A potentiometer on an analog input mapped to 0-99 is a simple first test of the display.

## Common mistakes

- Powering a 5 V module from a 3.3 V logic board: at VCC = 4.5 V the chip's VIH is 3.15 V, so 3.3 V is marginal at 5 V; confirm the module or use a 5 V board (source: [link](https://www.ti.com/lit/ds/symlink/sn74hc595.pdf), 6.3 Recommended Operating Conditions)
- Exceeding the supply rating: the absolute maximum VCC is 7 V (source: [link](https://www.ti.com/lit/ds/symlink/sn74hc595.pdf), 6.1)
- Loading outputs too hard: the sheet gives +/-6 mA drive at 5 V and a 35 mA absolute maximum per output, and the module's resistor values are not documented (source: [link](https://www.ti.com/lit/ds/symlink/sn74hc595.pdf), Features and 6.1)

## Not covered by the official source

- Chip facts only: the module is not documented. The digit current, common-anode or cathode type and number of 595 chips are unconfirmed.
- The SN74HC595 VIH row at 3.3 V is not tabulated; only 2 V, 4.5 V and 6 V rows exist.

## Sources

- [link](https://www.ti.com/lit/ds/symlink/sn74hc595.pdf) (TI SN54HC595/SN74HC595 datasheet SCLS041J, rev. Oct 2021; second-source maker)