# LS1205EFD33

**Littelfuse** · Surge Protection Devices (SPDs) · DFN-10(3x3)

LS1205EFD33 from Littelfuse, in a DFN-10(3x3). Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | IN | power_in | Power input pin; the datasheet gives the input voltage range as 2.7 V to 18 V. |
| 2 | IN | power_in | Power input pin; the datasheet gives the input voltage range as 2.7 V to 18 V. |
| 3 | IN | power_in | Power input pin; the datasheet gives the input voltage range as 2.7 V to 18 V. |
| 4 | FAULT\ | output | LS1205EF only; open-drain fault indicator that asserts low for input under-voltage, input over-voltage, output short and thermal shutdown, with output low voltage of 0.5 V max at 1 mA sink. |
| 5 | ILIM | passive | Current limit program pin; connect a resistor to ground to set the current limit, programmable from 1 A to 5 A. |
| 6 | SS | passive | Soft-start time program pin; connect a capacitor to ground to program the output slew rate (leaving it floating gives a fixed soft-start of about 1.7 ms typical). |
| 7 | EN | input | Enable pin with 1.29 V rising turn-on and 1.19 V falling turn-off thresholds; pull above the ON threshold to enable the IC and below the OFF threshold to disable it. |
| 8 | OUT | power_out | Power output pin, connected to IN through the internal 25 mΩ protection FET. |
| 9 | OUT | power_out | Power output pin, connected to IN through the internal 25 mΩ protection FET. |
| 10 | OUT | power_out | Power output pin, connected to IN through the internal 25 mΩ protection FET. |
| 11 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Littelfuse |
| Package | DFN-10(3x3) |
| Category | Circuit Protection |
| Pins | 11 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Input Voltage Range | VIN | 2.7 |  | 18 | V |  | 3 |
| Quiescent Current | IBIAS |  | 200 | 240 | µA |  | 3 |
| Shutdown Current | ISHDN |  | 6.5 | 10 | µA | VEN=0V | 3 |
| EN Input Leakage Current | IEN | -200 |  | 200 | nA | 0V ≤ VEN ≤ 5V | 3 |
| Input UVLO Threshold | VUVLO | 3.4 | 3.6 | 3.8 | V | LS1205EF | 3 |
| FAULT Leakage Current | IFlkg |  | 0.01 | 1 | µA | LS1205EF, No Fault, VFAULT\=5V | 3 |
| Current Limit Program Range | IINLIM | 1 |  | 5 | A |  | 3 |
| Current Limit | IINLIM | 3.6 | 4 | 4.5 | A | RLIM=2.7kΩ | 3 |
| Soft-start Time |  | 1.2 | 1.7 | 2.2 | msec | SS float | 3 |
| Input voltage (VIN, EN, VCP, FAULT\) | VIN, EN, VCP, FAULT\ | -0.3 |  | 20 | V | Reference to GND | 2 |
| Other pins voltage |  | -0.3 |  | 6.5 | V | Reference to GND; all other pins | 2 |
| ESD, Human Body Model (HBM) |  | -2000 |  | 2000 | V | JESD22-A114F | 2 |
| Junction Temperature Range |  | -40 |  | 125 | °C |  | 2 |
| Storage Temperature Range |  | -65 |  | 125 | °C |  | 2 |
| Lead Temperature (Soldering 10s) |  |  |  | 260 | °C | 10s soldering | 2 |
| Input Voltage (VIN) | VIN | 2.7 |  | 18 | V |  | 2 |
| Junction Temperature Range |  |  |  | 125 | °C |  | 2 |
| Maximum Power Dissipation |  |  |  | 1.89 | W | TA=25°C | 2 |
| EN Turn-on Threshold | VENR |  | 1.29 |  | V | EN Rising | 3 |
| EN Turn-off Threshold | VENF |  | 1.19 |  | V | EN Falling | 3 |
| EN Hysteresis | VENHYS |  | 100 |  | mV |  | 3 |
| Clamping Output Voltage | VCLP |  | 14.4 |  | V | LS1205EF | 3 |
| UVLO hysteresis | VHYS |  | 300 |  | mV | LS1205EF | 3 |
| FAULT Output Low Voltage |  |  | 0.5 |  | V | LS1205EF, Fault, ISINK=1mA | 3 |
| Protection FET RON | RDSON |  | 25 |  | mΩ |  | 3 |
| Current Limit Setting Factor | KLIM |  | 10.5 |  | A*kΩ | IINLIM=1A~5A | 3 |
| Soft-start Time | TSS |  | 25 |  | msec | CSS=100nF | 3 |
| OUT Discharging Resistance | RDischarge |  | 120 |  | Ω | VIN=5V and VEN=0V | 3 |
| Thermal Shutdown Temperature | TSD |  | 140 |  | °C |  | 3 |
| Thermal Shutdown Hysteresis | THYS |  | 20 |  | °C |  | 3 |
| Junction Temperature Regulation | TLIIM |  | 125 |  | °C |  | 3 |
| Thermal Resistance (junction to ambient) | θJA |  | 53 |  | °C/W |  | 2 |
| Thermal Resistance (junction to case) | θJC |  | 25 |  | °C/W |  | 2 |

## Materials and finish

As the datasheet states them (page.json `metadata.appearance`; the 3D model's colours follow it).

| Part | Material | Colour / plating | Datasheet says | Page |
|---|---|---|---|---|
| contacts | copper |  | ■ The GND terminal must be tied to the PCB ground plane at the terminal of the IC. The PCB ground should be a copper plane or island on | 8 |

## CAD (KiCad official)

- Symbol: `LS1205EFD33`
- Footprint: `Package_DFN_QFN:DFN-10-1EP_3x3mm_P0.5mm_EP1.55x2.48mm`
- 3D model: DFN-10(3x3) (KiCad packages3D, STEP)
- 3D model files: `ls1205efd33-etched.step` / `ls1205efd33-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ls1205efd33.step` / `ls1205efd33.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Littelfuse datasheet](docs/ls1205efd33-datasheet.pdf) (10 pp, sha256 `377e453a7b81c70b`, retrieved 2026-10-30, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/ls1205efd33-datasheet.pdf)