TLV1117 PCB Design Guide: Footprint, Pinout, and Alternatives
TI's 800 mA 1117-family linear regulator, adjustable and fixed, with two silicon generations shipping under one part number
The TLV1117 is Texas Instruments' branch of the 1117 regulator family: a linear regulator rated for 0.8 A from inputs up to 15 V, offered as an adjustable part built around a 1.25 V reference and as fixed versions from 1.5 V to 5.0 V (TLV1117-15 through TLV1117-50; the adjustable range is 1.25 V to 13.8 V). The workhorse package is the 4-pin SOT-223 (TI code DCY), with TO-252, TO-220, TO-263, and WSON options spread across two die generations. The part is active, and the current datasheet is SLVS561O Rev. O, revised June 2025.
Pick it when you want the classic 1117 footprint from a first-tier supply chain: it drops into the pads where an AMS1117 or one of its clones would otherwise go, a positioning TI never states but the pinout supports. Do not pick it as a modern LDO. The silicon you must design for drops 1.2 V typical at 800 mA, and the adjustable version idles at 5 mA of quiescent current, which rules out battery rails on both counts. TI's newer die improves fixed-output dropout to 0.8 V typical and quiescent current to 65 µA, and adds soft-start, foldback current limit, UVLO, and an output pulldown, but only on the fixed versions, and you cannot order the new silicon deterministically.
The recurring board-level failures are predictable: silicon that does not match the datasheet column you read, too little input headroom for a dropout that is anything but low, output capacitors that satisfy one version's stability rules and violate the other's, an adjustable rail that drifts high because nothing draws the minimum load, and SOT-223 thermal math nobody ran, on a package whose tab is the output net, not ground. Each is covered below.
What breaks boards
One part number, two different chips: check the packaging label
TI ships the TLV1117 as either legacy-chip or new-chip silicon under overlapping orderable part numbers, and the differences are material: fixed-output dropout is 1.2 V versus 0.8 V typical at 800 mA, fixed-output quiescent current is 5 mA versus 65 µA, and soft-start, foldback current limit, UVLO, output pulldown, and no-minimum-load operation exist only on the new-chip fixed versions. The fab source is identified only by the packaging label: CSO: SFB is the legacy chip, CSO: RFB or FFAB is the new chip. Unless you control which one arrives, design to the legacy numbers.
Budget 1.2 V of dropout; a Li-ion cell cannot feed a 3.3 V rail
Ignore the low-voltage connotation of the TLV prefix. The adjustable and legacy parts drop 1.2 V typical at 800 mA, 1.3 V max for the C grade and 1.4 V max for the I grade, which is why TI's recommended minimum input for the TLV1117-33 is 4.7 V. A single lithium-ion cell spends most of its discharge below that, so Li-ion to 3.3 V does not work here. Only the new-chip fixed versions improve to 0.8 V typical / 1.2 V max, and the previous gotcha explains why you cannot count on receiving them.
Output capacitor rules differ by version, and they conflict
The adjustable part is a classic 1117: TI's description calls for a minimum 10 µF tantalum at the output, and the design requirements specify stability with tantalum and aluminum electrolytic capacitors with an ESR between 0.2 Ω and 10 Ω. A bare low-ESR ceramic sits below that window, outside the characterized envelope. The new-chip fixed output inverts the rule: its specified COUT ESR range is 2 mΩ to 500 mΩ, with TI advising a parallel low-ESR MLCC when the output capacitor's ESR is higher. Fit the capacitor for the version and output option actually on your board.
The adjustable version drifts high without a minimum load
The adjustable TLV1117 needs load current to stay in regulation: 1.7 mA typical and 5 mA worst case at VIN = 15 V. If the feedback divider plus the real load sinks less, the output climbs at light load; the rail measures fine under load and high at idle. Size the divider across the 1.25 V reference so it alone guarantees the worst-case 5 mA instead of relying on the load. The new-chip fixed versions have no minimum load requirement, but per the first gotcha you should not design around receiving one.
SOT-223 thermal math, and the tab is the output net
Dissipation is (VIN − VOUT) × IOUT, and the DCY (SOT-223) junction-to-ambient figures are unforgiving: 61.6 °C/W (new chip, adjustable), 95.4 °C/W (new chip, fixed), and 104.3 °C/W (legacy). On a legacy part every watt lifts the junction 104.3 °C above ambient, against a 150 °C absolute-maximum junction. With inputs allowed up to 15 V (16 V absolute max), a legal-on-paper design can still cook. Spread heat with a generous copper pour on the tab, and route accordingly: on this pinout the tab is OUTPUT, not ground. For big step-down ratios, put a buck converter in front.
Key specifications
| Parameter | Value | Source |
|---|---|---|
| Input voltage range | 2.7 V min / 15 V max (TLV1117 adjustable); fixed versions: 2.9 V min (TLV1117-15), 3.2 V (TLV1117-18), 3.9 V (TLV1117-25), 4.7 V (TLV1117-33), 6.4 V (TLV1117-50), all 15 V max | SLVS561O Rev O, Section 5.3 Recommended Operating Conditions |
| Output current | IOUT 0.8 A max | SLVS561O Rev O, Section 5.3 Recommended Operating Conditions |
| Output voltage options | Fixed: 1.5 V (TLV1117-15), 1.8 V (TLV1117-18), 2.5 V (TLV1117-25), 3.3 V (TLV1117-33), 5.0 V (TLV1117-50); adjustable: 1.25 V to 13.8 V; output accuracy (new chip): +/-1.0% at TJ = 25 C for both fixed and adjustable | SLVS561O Rev O, Section 1 Features (output voltage options, output accuracy) + Section 5.6 Electrical Characteristics, VOUT rows |
| Reference voltage (adjustable) | 1.25 V typ, 1.238 min / 1.262 max (VIN - VOUT = 2V, IOUT = 10mA, TJ = 25 C, TLV1117C/I); over VIN - VOUT = 1.4V to 10V, IOUT = 10mA to 800mA: 1.225 min / 1.27 max (TLV1117C), 1.2 min / 1.29 max (TLV1117I) | SLVS561O Rev O, Section 5.6 Electrical Characteristics, VREF row |
| Dropout voltage | 1.2 V typ / 1.3 V max (TLV1117C) and 1.2 V typ / 1.4 V max (TLV1117I) at IOUT = 800mA; new chip, fixed output: 0.8 V typ / 1.2 V max at IOUT = 800mA (TLV1117C/I) | SLVS561O Rev O, Section 5.6 Electrical Characteristics, VDO rows |
| Quiescent current | Adjustable output: 5 mA typ / 10 mA max (TLV1117C), 5 mA typ / 15 mA max (TLV1117I) at VIN <= 15V; new chip fixed output: 65 uA typ / 110 uA max (IOUT = 0mA, VIN = 15V) | SLVS561O Rev O, Section 5.6 Electrical Characteristics, IQ rows |
| Minimum load current (adjustable) | 1.7 mA typ / 5 mA max (VIN = 15V, TLV1117C/I); description states to use a minimum 1.7 mA (typical) load current for stable operation and a minimum 10 uF tantalum capacitor at the output; new-chip fixed version has no minimum load current requirement | SLVS561O Rev O, Section 5.6 Electrical Characteristics, IMIN(LOAD) row + Section 3 Description |
| Output capacitor / ESR (stability) | Adjustable output: designed to be stable with tantalum and aluminum electrolytic output capacitors with an ESR between 0.2 Ohm and 10 Ohm (Note A: output capacitor selection is critical for regulator stability); new chip, fixed output: COUT ESR 2 mOhm min / 500 mOhm max, with note that maximum supported ESR range is 0.5 Ohm and to place a low-ESR MLCC for output capacitors with higher ESR values | SLVS561O Rev O, Section 7.2.1 Design Requirements (Adjustable Output), Note A + Section 5.3 Recommended Operating Conditions, COUT ESR row and note (1) |
| Abs max / thermal | VIN continuous -0.3 to 16 V abs max; operating TJ -50 to 150 C abs max; RthetaJA for DCY (SOT-223): 95.4 C/W (new chip, fixed) / 61.6 C/W (new chip, adjustable) / 104.3 C/W (legacy chip) | SLVS561O Rev O, Section 5.1 Absolute Maximum Ratings + Section 5.4 Thermal Information (Legacy Chip) + Section 5.5 Thermal Information (New Chip) |
| Pinout (SOT-223 and power packages) | Pin 1 = ADJ/GND, pin 2 = OUTPUT, pin 3 = INPUT on DCY (SOT-223), KVU (TO-252), KCS/KCT (TO-220), and KTT (TO-263); the tab is OUTPUT | SLVS561O Rev O, Section 4 Pin Configuration and Functions, Figures 4-1 to 4-4 + Table 4-1 |
Verified against the manufacturer datasheet on 2026-07-10. Confirm the current revision before production use.
Alternatives
- AMS1117: the ubiquitous low-cost 1117 the TLV1117 usually replaces: same pinout and footprint, but a non-TI part (Advanced Monolithic Systems) with widespread clones of varying quality.
- LM1117: TI's other 800 mA 1117-family linear regulator, same SOT-223 pinout with adjustable and fixed options; pick between the two by price and availability.
- TLV1117LV: TI's true low-VIN, low-dropout successor: stable with ceramic output capacitors and no minimum load requirement, but not pin-compatible with the 1117 SOT-223 pinout in all packages, so check the footprint before swapping.
- AZ1117: Diodes Incorporated's pin-compatible 1117, commonly used as an AMS1117 substitute when a second source is needed.
Common questions
- What is the dropout voltage of the TLV1117?
- 1.2 V typical at 800 mA for the adjustable and legacy parts, with 1.3 V max (C grade) or 1.4 V max (I grade). The new-chip fixed versions specify 0.8 V typical / 1.2 V max at 800 mA, but because legacy and new silicon ship under overlapping part numbers, budget for the 1.2 V typical figure.
- Can the TLV1117-33 regulate 3.3 V from a single Li-ion cell?
- No. TI's recommended minimum input for the TLV1117-33 is 4.7 V, a consequence of the roughly 1.2 V dropout, and a Li-ion cell spends most of its discharge curve below that. Use a genuinely low-dropout regulator for battery rails.
- What output capacitor does the TLV1117 need?
- For the adjustable version, a minimum 10 µF tantalum at the output; TI specifies stability with tantalum and aluminum electrolytic capacitors with an ESR between 0.2 Ω and 10 Ω, so a ceramic-only output is outside the window. The new-chip fixed output is the opposite: low-ESR ceramics within a 2 mΩ to 500 mΩ COUT ESR range.
- Why does my adjustable TLV1117 output rise at light load?
- The adjustable version requires a minimum load current to stay in regulation: 1.7 mA typical and 5 mA worst case at VIN = 15 V. Size the feedback divider so it sinks the worst-case 5 mA on its own; then the rail holds even with the load disconnected. The new-chip fixed versions have no minimum load requirement.