MC34063A
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TI monolithic DC-DC converter control, SOIC-8. Buck, boost, or inverting; on-chip 1.5 A switch, 3-40 V. Datasheet-verified.
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markdownMC34063A
Texas Instruments · DC-DC converter controller · SOIC-8
A complete DC-DC converter control circuit in SOIC-8, one of the oldest and most widely used switching-regulator chips. On board it has a temperature-compensated reference, a comparator, an oscillator whose frequency a single capacitor sets, a current-limit sense, a driver, and a 1.5 A output switch. With a handful of external parts (inductor, diode, resistors) it builds a step-down (buck), step-up (boost), or voltage-inverting converter over a 3 to 40 V input. It is the go-to for a cheap adjustable boost or buck when an integrated-inductor module is overkill.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | Switch Collector | output | High-current internal switch (Q1) collector. Rated 40 V max, up to 1.5 A peak switch current. Connects to the inductor/diode node of the boost/buck/inverting converter. |
| 2 | Switch Emitter | output | High-current internal switch (Q1) emitter output. Rated 40 V max. Combined with pin 1 forms the internal Darlington output switch used to drive the converter's power inductor. |
| 3 | Timing Capacitor | passive | Oscillator timing capacitor (C_T) pin. An external capacitor to GND sets the oscillator frequency (up to 100 kHz). Charge current typ. 35 uA, discharge typ. 220 uA, giving discharge/charge ratio ~6.5. |
| 4 | GND | power_in | Device ground reference. On the DRJ (QFN) package the exposed thermal pad is bonded internally to this pin. |
| 5 | Comparator Inverting Input | input | Inverting input to the internal error comparator. Non-inverting input is internally tied to the 1.25-V (typ.) reference. Connect a resistor divider from Vout to set the regulated output voltage. Input bias current typ. -20 nA (max -400 nA). Absolute range -0.3 V to 40 V. |
| 6 | VCC | power_in | Logic supply voltage. Tie to VIN. Operating range 3 V to 40 V (absolute max 40 V). Standby supply current typ. ~2.5 mA (max 4 mA at 5 V, C_T = 1 nF). |
| 7 | Ipk Sense | input | Current-limit sense input. An external resistor (Rsc) between VCC (pin 6) and this pin sets the peak switch current; the internal circuit terminates the switch on-time when the voltage across Rsc reaches ~300 mV (typ., 250-350 mV). |
| 8 | Driver Collector | output | Darlington driver transistor (Q2) collector input. Provides access to the driver stage for external switch configurations or Darlington operation (tie to pin 1 for internal Darlington). Rated 40 V max, driver collector current 100 mA max. |
Key specifications
| Parameter | Value |
|---|---|
| Type | DC-DC converter controller |
| Topologies | buck, boost, inverting |
| Switch current | 1.5 A (on-chip) |
| Input voltage | 3-40 V |
| Oscillator | set by one capacitor (up to 100 kHz) |
| Reference | 1.25 V |
| Current limit | Ipk sense pin |
| Package | SOIC-8 |
Ordering variants
Same part, different packaging or reel option.
MC34063AD (SOIC-8)MC34063AP (PDIP-8)
CAD (KiCad official)
- Symbol:
Regulator_Switching:MC34063AD - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SOIC-8 (KiCad packages3D)
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (32 pp, sha256
bad86a3b68c35766, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).