# LD5521DGL

**Leadtrend Tech** · AC-DC Controllers And Regulators · SOT-26

LD5521DGL from Leadtrend Tech, in a SOT-26. 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 | GND | power_in | Ground reference pin for the controller. |
| 2 | COMP | passive | Output of the error amplifier for voltage compensation; open-loop voltage is 5.3V typical (5.0V to 5.6V), and a capacitor of 1nF to 10nF is required on this pin for stable operation. |
| 3 | FB | input | Auxiliary voltage sense for brown-in/brown-out, quasi-resonant detection and FB OVP; the FB OVP trip voltage is 3.5V typical (3.4V to 3.6V) and the absolute maximum rating is -0.3V to 6V. |
| 4 | CS | input | Current sense pin that senses the MOSFET current; maximum input voltage is 0.52V typical (0.49V to 0.55V), a CS capacitor of 47pF to 470pF is recommended, and the absolute maximum rating is -0.3V to 6V. |
| 5 | VCC | power_in | Supply voltage pin with recommended range 8.0V to 26.5V and absolute maximum 30V; VCC OVP trips at 28.5V typical and a 3.3uF to 10uF capacitor is recommended. |
| 6 | OUT | output | Gate drive output that drives the external power MOSFET with 250mA/-500mA driving capability, with absolute maximum range -0.3V to VCC. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Leadtrend Tech |
| Package | SOT-26 |
| Category | Power Management (PMIC) |
| Pins | 6 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Supply Voltage VCC | VCC | -0.3 |  | 30 | V |  | 4 |
| OUT pin voltage |  | -0.3 |  |  | V |  | 4 |
| COMP, FB, CS pin voltage |  | -0.3 |  | 6 | V |  | 4 |
| Maximum Junction Temperature |  |  |  | 150 | C |  | 4 |
| Storage Temperature Range |  | -65 |  | 150 | C |  | 4 |
| Package Thermal Resistance (SOT-26) | JA |  |  | 200 | C/W |  | 4 |
| Power Dissipation (SOT-26) |  |  |  | 200 | mW | Ambient Temperature = 85C | 4 |
| Lead temperature |  |  |  | 260 | C | Soldering, 10sec | 4 |
| ESD Voltage Protection, Human Body Model |  |  |  | 2.5 | KV | Human Body Model | 4 |
| ESD Voltage Protection, Machine Model |  |  |  | 250 | V | Machine Model | 4 |
| Operating Junction Temperature |  | -40 |  | 125 | C |  | 4 |
| Supply VCC Voltage | VCC | 8 |  | 26.5 | V |  | 4 |
| VCC Capacitor |  | 3.3 |  | 10 | µF |  | 4 |
| Start-up resistor Value (AC Side, Half Wave) |  | 400 |  | 2 | K/M |  | 4 |
| Comp Pin Capacitor |  | 1 |  | 10 | nF |  | 4 |
| CS Pin Capacitor Value |  | 47 |  | 470 | pF |  | 4 |
| Startup Current | ICC_ST |  |  | 5 | µA |  | 5 |
| Operating Current | ICC_OP1 |  |  | 0.5 | mA | VCOMP=0V, OUT=1nF | 5 |
| Operating Current | ICC_OP2 |  |  | 1.5 | mA | VCOMP=3V, OUT=1nF | 5 |
| Operating Current (OLP Auto) | ICC_OPA2 |  |  | 0.55 | mA | OLP Auto | 5 |
| Holding Current | ICC_OPL2 |  |  | 500 | µA | VCC=10V | 5 |
| UVLO(OFF) | VCC_OFF | 6.5 | 7.5 | 8.5 | V |  | 5 |
| UVLO(ON) | VCC_ON | 12.5 | 13.5 | 14.5 | V |  | 5 |
| Latch-Off Release Voltage | PDR | 3.6 | 4.6 | 5.6 | V |  | 5 |
| VCC OVP Level | VCC_OVP | 27 | 28.5 | 29.5 | V |  | 5 |
| Short Circuit Current | ICOMP | 0.1 | 0.125 | 0.15 | mA | VCOMP=0V | 5 |
| Open Loop Voltage | VCOMP_OPEN | 5 | 5.3 | 5.6 | V | COMP pin open | 5 |
| Maximum Input Voltage (CS) | VCS_LIMIT | 0.49 | 0.52 | 0.55 | V |  | 5 |
| Brown In Trip Level | IBNI | 85 | 95 | 101.5 | µA |  | 5 |
| Brown Out Trip Level | IBNO | 79 | 85 | 93.5 | µA |  | 5 |
| Brown Out De-bounce Time | TDB_BNO | 46 | 60 | 64 | ms | VCOMP=3V | 5 |
| QRD OVP Trip voltage Level | VFB_OVP | 3.4 | 3.5 | 3.6 | V |  | 6 |
| Frequency Swapping | FSW_MOD | -12 |  | 12 | % |  | 6 |
| Green Mode Frequency | FSW_GREEN | 25 |  | 27 | kHz |  | 6 |
| Temp. Stability | FSW_TS | 3 |  | 5 | % |  | 6 |
| Output High Level | VOH | 8 |  | 15 | V | VCC=15V, IO=20mA | 6 |
| Rising Time | Tr | 200 |  | 350 | ns | VCC=15V CL=1000pF | 6 |
| Falling Time | Tf | 80 |  | 150 | ns | VCC=15V CL =1000pF | 6 |
| OLP Trip Level | VOLP | 4.3 | 4.5 | 4.7 | V |  | 6 |

## CAD (KiCad official)

- Symbol: `LD5521DGL`
- Footprint: `Package_TO_SOT_SMD:SOT-23-6`
- 3D model: SOT-26 (KiCad packages3D, STEP)
- 3D model files: `ld5521dgl-etched.step` / `ld5521dgl-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ld5521dgl.step` / `ld5521dgl.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Leadtrend Tech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603125093509701632) (13 pp, sha256 `cff90ee1513ad733`, retrieved 2026-10-17, 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/ld5521dgl-datasheet.pdf)