Spark Logic

GStek GS72V3 synchronous buck controller connection guide

GStek GS72V3 synchronous buck controller (PSOP-8 (SP)) connection guide. Check supply and startup. Trace the bootstrap and MOSFET stage.

PSOP-8 (SP)

9 contacts Current package

Green Solution Technology (GStek) · Eight leads with an exposed ground pad. The documented order code is GS72V3SP-R.

Check supply and startup

Required

On an unpowered board, identify the controller supply at pin 5 and the separate VIN connection at the high-side MOSFET drain. Some boards use the same rail for both. Keep the existing VCC bypass capacitor and COMP/EN compensation network in circuit.

  • Controller supply
    • VCC bypass capacitor positive
    • Controller supply rail
  • Power-stage input
    • Power-stage VIN rail
    • High-side MOSFET drain
    • VIN bulk capacitor positive
  • Ground
    • VCC bypass capacitor return
    • Power-stage input capacitor return
    • Bench supply return
  • Shutdown and compensation
    • Existing compensation network
    • Open-drain shutdown control when fitted

Bench checks

  • With power off, verify pin 3 and EP9 connect to board ground and check both supply rails for shorts. Use a current-limited supply at the board’s rated input voltage.
  • Check for 4.5–13.2 V from pin 5 to GND and verify the MOSFET drain supply separately. VCC above the power-on threshold does not prove that VIN has reached the power stage.
  • Check whether an external transistor holds COMP/EN below 0.3 V. Release the pull-down to allow startup. Applying a logic-high drive here interferes with the error amplifier.

GStek GS72V3, rev. 0.4, pp. 3, 5–6, 9

Connection scenarios

Measure the output and feedback divider

Trace FB to the divider after L1. This drawing isolates the DC sense path. Retain the existing AC compensation connected to FB and COMP/EN.

GS72V3 output feedback divider with upper and lower resistorsGS72V3FBGNDFiltered VOUTRupperRlower≈ 0.6 VGND
  • Filtered output
    • VOUT after L1
    • Rupper.1
    • Output capacitor positive
  • Divider midpoint
    • Rupper.2
    • Rlower.1
    • Compensation network FB connection
  • Compensation output
    • Compensation network COMP connection
  • Ground
    • Rlower.2
    • Output capacitor return

Bench checks

  • Measure VOUT at the output capacitor and FB at pin 6 after startup. In regulation FB should be close to 0.6 V.
  • Compare VOUT with 0.6 × (1 + Rupper/Rlower). Read the fitted resistor values from the schematic or measure them with power off while accounting for parallel paths.
  • If FB is correct but VOUT is wrong, check the divider and remote sense trace. If FB never reaches its target, check VIN, VCC and the gate drive before changing compensation.

GStek GS72V3, rev. 0.4, pp. 3, 5, 9, 11–12

PSOP-8 (SP) wiring map

External wiring example · Measure the output and feedback divider

Highlighted contacts are used in the required step or selected circuit. Select a contact to highlight its wiring nets.

PSOP-8 (SP) · Top view, rotated from the datasheet figure so pin 1 is at upper left. The ground pad is on the underside.
Dashed outline shows the underside pad schematically. See the package drawing for the footprint.
Selected pin details

2 · UGATE

Gate drive · Outputs

Drives the external high-side N-channel MOSFET. Its source and gate-drive return are at PHASE.

GStek GS72V3, rev. 0.4, pp. 2–3

Electrical limits · Pin in the reference

Models and documents

The pin map and measurements use the full rev. 0.4 datasheet for GS72V3SP-R. The rev. 1.0 product brief shows a different overcurrent setting network. Check the board and document revision before interpreting current limit or replacing its parts.

GS72V3SP-R
PSOP-8 (SP) in tape and reel.