Input power and return
VIN feeds the power switches; VCC powers the controller. Join them in the documented single-supply circuit.
APW8805 / APW8805A / APW8805B buck converter pinout
The APW8805 family integrates the switches for a 3 A synchronous step-down regulator. All three versions share the same TDFN pin map.
TDFN 3 × 3 mm (QB)
11 contacts Current packageTDFN 3 × 3 mm (QB) pinout
Dashed outline shows the underside pad schematically. See the package drawing for the footprint.
1 · FB
Divider midpoint. Sense the filtered output here; the nominal regulated feedback voltage is 0.8 V.
Build the 1.05 V buck circuit
- Input
- CIN.1
- RPG.1
- Input supply positive
- Ground
- CIN.2
- COUT1.2
- COUT2.2
- R2.2
- Input return
- Enable
- →
- Enable control
- Switch node
- →
- →
- L1.1
- Output
- L1.2
- R1.1
- COUT1.1
- COUT2.1
- Load positive
- Feedback
- →
- R1.2
- R2.1
- Power good
- →
- RPG.2
- Power-good monitor
All 11 pins
| Pin | Signal | Direction | Function |
|---|---|---|---|
| 1 | FB Input | Input | Divider midpoint. Sense the filtered output here; the nominal regulated feedback voltage is 0.8 V. |
| 2 | VCC Supply | Supply | Control supply. Connect to the input rail in the single-supply circuit. |
| 3 | VIN Supply | Supply | Power-stage input. Place the input ceramic capacitor close to VIN and ground. |
| 4 | GND Return | Return | Ground; connect to pin 5 and the exposed pad. |
| 5 | GND Return | Return | Ground; connect to pin 4 and the exposed pad. |
| 6 | SW Output | Output | Switch node, tied to pin 7 and the inductor input. |
| 7 | SW Output | Output | Switch node, tied to pin 6 and the inductor input. |
| 8 | NC No connection | No connection | Leave unconnected. |
| 9 | POK Output | Output | Open-drain status output. Add a pull-up; check the receiver voltage rating. |
| 10 | EN Input | Input | Active-high enable. Drive to a defined logic level; see model-specific thresholds. |
| 11 | GND Thermal pad | Thermal pad | Exposed thermal pad. Solder to board ground along with pins 4 and 5. |
Signal assignments
Electrical limits
| Parameter | Limit | Conditions and source |
|---|---|---|
| VCC and VIN tied2.6–6 V | 2.6–6 V | Single-supply application. Separate VIN may operate down to 2 V while VCC still needs at least 2.6 V. ANPEC APW8805 / A / B, Recommended Operating Conditions |
| Feedback0.8 V nominal | 0.8 V nominal | Use the electrical table and divider equation for the exact variant. ANPEC APW8805 / A / B, Electrical Characteristics |
| PWM oscillator0.85–1.15 MHz | 0.85–1.15 MHz | 1 MHz typical; automatic variants can enter PFM at light load. ANPEC APW8805 / A / B, Electrical Characteristics |
| Output current3 A rated | 3 A rated | Check inductor current, PCB dissipation and voltage headroom in the intended circuit. ANPEC APW8805 / A / B, Typical Application Circuit |
Models and documents
Choose the exact suffix for the enable thresholds and light-load behavior. The APW8805B overview lists 0.6 V as a minimum output, while its feedback specification and application equation use 0.8 V. The circuit here uses the documented 0.8 V reference.
- APW8805
- Automatic PFM/PWM. Order code: APW8805QBI-TRG.
- APW8805A
- Forced PWM. Order code: APW8805AQBI-TRG.
- APW8805B
- Automatic PFM/PWM; documented startup into a pre-biased output. Order code: APW8805BQBI-TRG.
- Datasheet for APW8805· Rev. A.4; pin configuration, operating limits and typical application.
- Datasheet for APW8805A· Rev. A.4; pin configuration, operating limits and typical application.
- Datasheet for APW8805B· Rev. A.2; pin configuration, operating limits and typical application.
- Source register· Original document URLs, revisions and file checksums.