Spark Logic

ATtiny45 / ATtiny85 connection guide

ATtiny45 / ATtiny85 QFN/MLF-20 wiring guide with power, signal assignments, and bench checks.

PDIP-8 8 contacts
SOIC-8 8 contacts
TSSOP-8 8 contacts

QFN/MLF-20

21 contacts Current package

Microchip Technology · 20 numbered contacts. The underside pad appears below the contact map. See the individual package drawings for footprint dimensions.

4 KiB flash · 256 B SRAM · 256 B EEPROM. Choose the marked order code for voltage, clock, and temperature.

Power and reset

Required

Use a current-limited supply at a voltage permitted by the order code and system clock. Tie the listed supply pins to that rail. Fit one 100 nF ceramic capacitor close to each supply-and-ground pair. Use a 10 kΩ reset pull-up for this bench circuit.

100 nF per supply pair between Target rail and GroundTarget rail100 nF per supply pairGround
10 kΩ between Target rail and ResetTarget rail10 kΩReset

Bench checks

  • With power off, check for a short across the supply. Power on and measure voltage at every supply pin and at reset.
  • Check the clock source configured by CKSEL. If a used part expects an external clock, provide it before attempting serial programming.

AN2519 §§2–3 and 2586Q · Pin descriptions and clock source

Connection scenarios

Program and read the signature over ISP

Start from the power and reset circuit. Attach a voltage-compatible AVR in-system programmer and use the target voltage as its reference. Connect reset, serial data in/out, and SCK as shown.

AVR programmer wired to target voltage reference, ground, reset, serial data in/out and clock.ProgrammerAVR targetVTGVCCGNDGNDRESETPB5MOSIPB0MISOPB1SCKPB2
  • Target voltage sense
  • Common ground
  • Reset assertion
  • Serial data into target
  • Serial data out of target
  • Programming clock

Bench checks

  • Read the device signature before writing flash or fuses. If it fails, verify target power, the clock source, programmer direction, and the selected device.
  • If the programmer offers an adjustable SCK, start below one quarter of the target clock and check the data sheet’s SCK high and low timing. Disconnect or isolate other peripherals that drive the programming lines.
  • Disable power output on the programmer if the target has its own bench supply. Confirm the programmer’s VTG behavior in its manual.

AN2519 §4.1 and 2586Q · Serial Programming Pin Mapping

QFN/MLF-20 wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

Top view · Pin 1 at the upper left · Schematic outline
EP is the exposed center pad on the underside.
Selected pin details

20 · DNC

Reserved · NC / reserved

Leave this package contact electrically unconnected.

2586Q · Pinout and peripheral signal descriptions

Electrical limits · Pin in the reference

Models and documents

Each package lists the documented order codes and variants covered by this map. Select the marked model to see its peripheral assignments and memory. Check the exact order code and datasheet revision before laying out a PCB.

ATtiny45
4 KiB flash · 256 B SRAM · 256 B EEPROM. Choose the marked order code for voltage, clock, and temperature.
ATtiny45V-10MU
4 KiB flash · 256 B SRAM · 256 B EEPROM · 1.8–5.5 V · 10 MHz maximum · -40 to +85 °C
ATtiny45V-10MUR
4 KiB flash · 256 B SRAM · 256 B EEPROM · 1.8–5.5 V · 10 MHz maximum · -40 to +85 °C
ATtiny45-20MU
4 KiB flash · 256 B SRAM · 256 B EEPROM · 2.7–5.5 V · 20 MHz maximum · -40 to +85 °C
ATtiny45-20MUR
4 KiB flash · 256 B SRAM · 256 B EEPROM · 2.7–5.5 V · 20 MHz maximum · -40 to +85 °C
ATtiny85
8 KiB flash · 512 B SRAM · 512 B EEPROM. Choose the marked order code for voltage, clock, and temperature.
ATtiny85V-10MU
8 KiB flash · 512 B SRAM · 512 B EEPROM · 1.8–5.5 V · 10 MHz maximum · -40 to +85 °C
ATtiny85V-10MUR
8 KiB flash · 512 B SRAM · 512 B EEPROM · 1.8–5.5 V · 10 MHz maximum · -40 to +85 °C
ATtiny85-20MU
8 KiB flash · 512 B SRAM · 512 B EEPROM · 2.7–5.5 V · 20 MHz maximum · -40 to +85 °C
ATtiny85-20MUR
8 KiB flash · 512 B SRAM · 512 B EEPROM · 2.7–5.5 V · 20 MHz maximum · -40 to +85 °C