UCC3809P-2 - Economy Primary Side PWM Controller, 8-VSSOP | TI
Référence : UCC3809P-2 ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $1.65 | $1,65 |
| 10 | $1.42 | $14,20 |
| 100 | $1.05 | $105,00 |
| 500 | $0.86 | $430,00 |
| 1 000 | $0.72 | $720,00 |
UCC3809P-2 Présentation
A primary-side PWM controller (also called a current-mode controller) is the IC that regulates a switching power supply by sensing the current through the primary winding of a flyback or forward transformer on each switching cycle and modulating the duty cycle of the main power switch (typically a MOSFET). This forms a tight inner current loop nested inside a slower outer voltage loop, providing inherent line-cycle-by-cycle current limiting and excellent input-voltage transient response. Within the broader hierarchy, the UCC3809P-2 belongs to Power Management > DC-DC Converters > PWM Controllers > Current-Mode Controllers > Primary-Side Controllers.
Key differentiating features include a logic-level shutdown pin, accessible 5V reference that doubles as a low-power supply rail for housekeeping circuits, and BCDMOS process technology that allows the high-side driver output to swing close to the VDD rail. The -2 UVLO variant turns on at 15V and off at 8V, leaving a 7V hysteresis window that accommodates slow VDD rise in bias-wound flyback designs. Maximum duty cycle is set by a single resistor, eliminating the need for a separate oscillator timing capacitor divider.
Typical applications include AC-DC adapters (5W-50W class), isolated DC-DC modules in industrial 24V bus systems, auxiliary supplies in motor drives, bias supplies for telecom line cards, and low-cost standby converters. The wide VDD range and small VSSOP-8 footprint suit designs where PCB area is constrained and a tiny primary-side controller is preferred over a fully integrated flyback solution.
Design tip: When designing the VDD bias network, ensure the auxiliary winding and rectifier can deliver VDD above 15V at all load conditions but clamp transients below the absolute maximum (typically 18V). Add a small RC snubber on VDD if ringing exceeds the abs-max. The shutdown pin is active-low and may be tied to VREF through a resistor divider if unused.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found on TI's standalone UCC3809-2 product page.
Alternatives de remplacement direct pour UCC3809P-2 — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
UCC2809P-2
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
UCC3809P-1
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
UCC2809P-1
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
UCC3809D-2
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
UCC3809P-2 Valeurs maximales et caractéristiques électriques
| Topologie | Boost, Buck, Flyback, Forward |
| Type de sortie | DC-DC Controller (PWM) |
| Control Mode | Current-mode |
| Switching Frequency (max) | 1 MHz |
| Duty Cycle (max) | 100% (programmable) |
| FET Driver Source Current | 0.4 A |
| FET Driver Sink Current | 0.8 A |
| UVLO Thresholds (UCC3809-2) | 15 V on / 8 V off |
| Internal Reference | 5 V (accessible on VREF pin) |
| Startup Current | 100 uA (typ) |
| Shutdown Pin | Active-low, logic-level |
| Démarrage progressif | User-programmable (external cap on SS) |
| Plage de température de fonctionnement | 0 C to +70 C |
| Boîtier | 8-pin VSSOP (DGK) |
| Type de montage | Surface Mount |
| Statut RoHS | Compliant |
| Process Technology | BCDMOS |
Configuration des broches de UCC3809P-2
| Broche 1 | RT/CT — Oscillator timing resistor / capacitor |
| Broche 2 | COMP — Error amplifier output (compensation network) |
| Broche 3 | CS — Current-sense input (PWM comparator) |
| Broche 4 | GND — Ground |
| Broche 5 | OUT — Gate driver output to primary switch |
| Broche 6 | VDD — Supply voltage |
| Broche 7 | VREF — 5 V internal reference output |
| Broche 8 | SS/SD — Soft-start / shutdown (active-low) |
Applications typiques
UCC3809P-2 convient pour 6 applications: AC-DC Flyback Adapters (5W-30W), Isolated DC-DC Modules (24V Industrial Bus), Motor Drive Auxiliary Bias Supplies, Telecom Line-Card Standby Converters, Low-Cost Standby / Bias Converters, LED Lighting Driver Front-End.
AC-DC Flyback Adapters (5W-30W)
The UCC3809P-2 is a strong fit for 5W-30W universal-input (85-265VAC) isolated flyback adapters because its 0.4A source / 0.8A sink gate driver directly switches the primary-side MOSFET, eliminating an external gate-driver buffer. The 15V/8V UVLO window accommodates 12V-15V auxiliary bias windings with 7V of hysteresis to prevent nuisance restart under heavy load transients, and the 100 uA startup current keeps 5W standby designs below 100 mW no-load consumption per ErP Lot 6. Place the UCC3809P-2 between the rectified mains and the main MOSFET, with VDD supplied by an auxiliary winding. Compared to integrated offline converters like TinySwitch, the UCC3809P-2 requires more external parts but offers finer current-mode control and easier loop compensation.
Recommandé
Isolated DC-DC Modules (24V Industrial Bus)
In 24V industrial bus isolated DC-DC modules, the UCC3809P-2 provides primary-side regulation with current-mode control that yields clean step-load response across a 4:1 input range. The 1 MHz oscillator capability allows a small planar transformer, while the 5V accessible reference on the VREF pin can power housekeeping circuitry without a separate LDO. With VDD supplied by a tertiary winding regulated around 12V-15V, the 15V/8V UVLO prevents restart chattering during input dropout events. The device's BCDMOS rail-to-rail gate swing maximizes drive efficiency at high switching frequencies. Use the UCC2809P-2 variant for sub-zero industrial environments.
Recommandé
Motor Drive Auxiliary Bias Supplies
The UCC3809P-2 is a common choice for generating the 15V gate-drive bias rail in industrial motor drives that use IGBT or MOSFET inverters. Its isolated flyback topology keeps the control MCU safe from inverter switching transients, while the 15V/8V UVLO prevents the gate driver from chattering during brownout events on the 24V/48V DC bus. The 0.8A sink capability is well-matched to IGBT gate-charge removal, and the accessible 5V reference can power a small MCU supervisor or housekeeping ADC. Adding a TVS diode on VDD protects the UCC3809P-2 from motor-induced voltage spikes. The result is a robust, low-cost bias supply that survives the harsh EMI environment of a variable-frequency drive.
Recommandé
Telecom Line-Card Standby Converters
In telecom line cards operating from -48V nominal, the UCC3809P-2 supports a non-isolated buck topology that derives a 12V or 5V standby rail from the -48V bus. The 1 MHz oscillator allows a small buck inductor, and the 100 uA startup current minimizes quiescent draw from the always-on bus. The UCC3809P-2's 0.4A source / 0.8A sink driver easily switches a 100V-rated MOSFET suitable for -48V input. UVLO is typically bypassed by an external resistor network because the device's native 15V/8V window does not directly match -48V bus operation. For higher reliability telecom designs, the industrial-grade UCC2809P-2 is preferred.
Recommandé
Low-Cost Standby / Bias Converters
The UCC3809P-2 is widely used as a low-cost standby converter in TVs, set-top boxes, and home appliances where a tiny 8-pin VSSOP controller is preferred over a fully integrated solution. Its 100 uA startup current enables standby power under 30 mW in 5V/0.1A bias applications, satisfying Energy Star and DOE Level VI no-load limits. The user-programmable soft-start pin prevents transformer saturation at cold plug-in, while the accessible 5V reference doubles as a logic supply. Compared to monolithic TinySwitch or LinkSwitch devices, the UCC3809P-2 costs slightly more in BOM but offers a user-tunable oscillator, current limit, and duty cycle - advantages when adapting the same flyback transformer across multiple product variants.
Recommandé
LED Lighting Driver Front-End
The UCC3809P-2's 0.4A/0.8A gate driver and 1 MHz oscillator make it a candidate for the PFC-front-end or flyback front-end of an LED lighting driver. In a single-stage PFC-flyback design for 10W-30W LED fixtures, the UCC3809P-2 provides primary-side current-mode control that simplifies the PFC inductor design while delivering the constant-current regulation required by LED strings. The 15V/8V UVLO accommodates 12V auxiliary bias from a tertiary winding, and the small VSSOP-8 footprint fits the compact driver housings used in MR16 bulbs and downlights. Add a primary-side constant-current reference using the VREF pin and a few resistors for accurate LED current without secondary-side sensing.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour UCC3809P-2 — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | UCC2809P-2 | UCC3809P-1 | UCC2809P-1 | UCC3809D-2 |
|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | VSSOP-8 (DGK) | VSSOP-8 (DGK) - same | VSSOP-8 (DGK) - same | VSSOP-8 (DGK) - same | SOIC-8 (D) - larger 3.9mm body |
| UVLO Thresholds | 15 V on / 8 V off | 15 V on / 8 V off (same) | 8 V on / 6 V off (lower) | 8 V on / 6 V off (lower) | 15 V on / 8 V off (same) |
| Operating Temperature | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C |
| FET Driver Source Current | 0.4 A | 0.4 A (same) | 0.4 A (same) | 0.4 A (same) | 0.4 A (same) |
| FET Driver Sink Current | 0.8 A | 0.8 A (same) | 0.8 A (same) | 0.8 A (same) | 0.8 A (same) |
| Max Switching Frequency | 1 MHz | 1 MHz (same) | 1 MHz (same) | 1 MHz (same) | 1 MHz (same) |
| Startup Current (typ) | 100 uA | 100 uA (same) | 100 uA (same) | 100 uA (same) | 100 uA (same) |
| Process Technology | BCDMOS | BCDMOS | BCDMOS | BCDMOS | BCDMOS |
Principaux différenciateurs
- Higher 15V/8V UVLO window with 7V hysteresis (vs UCC3809P-1 (8V/6V UVLO))
- Industrial-temperature option drop-in compatible (vs UCC2809P-2 (-40C to +85C))
- BCDMOS process technology with rail-to-rail gate swing (vs UCC3809D-2 (SOIC-8 variant))
Notes de conception
Estimated: VDD startup current of 100 uA means the high-voltage startup resistor network must be sized to deliver at least 200 uA of initial VDD charging current to overcome quiescent draw and charge the VDD bypass capacitor above the 15V UVLO threshold within ~200 ms. For a 265VAC rectified input (375 VDC peak), a string of two 470 kOhm resistors in series typically works; add a 1 MOhm bleed to satisfy X-cap discharge safety standards. Verify that the auxiliary winding and rectifier can supply >10 mA of VDD current once the converter is running so the high-voltage startup resistor string is automatically defeated by the lower-impedance auxiliary path.
The UCC3809P-2 in VSSOP-8 (DGK) package has a theta_JA of approximately 200 C/W on a standard 1 oz 4-layer 1 square-inch copper pad. At 100 kHz switching with typical 5 mA quiescent current at 12V VDD, internal dissipation is ~60 mW and self-heating is negligible. However, ensure VDD stays below the 18V abs-max during transient ringing of the auxiliary winding - add a 1 uF ceramic bypass directly on the VDD pin and a 5.1V Zener to ground if the bias network has poor cross-regulation. The OUT pin can source 0.4A / sink 0.8A, but sustained DC source current above 100 mA may stress the die.
Per the TI UCC3809-2 datasheet layout guidelines: place the VDD bypass capacitor (1 uF ceramic) within 5 mm of pin 6, the VREF capacitor (0.1 uF ceramic) within 5 mm of pin 7, and the gate-drive series resistor within 5 mm of pin 5 to suppress ringing. Keep the CS-pin current-sense trace short and away from the OUT trace to avoid noise coupling into the PWM comparator. Provide a clean ground star point at pin 4 with separate returns for the gate-drive loop and the current-sense ground. Use a 2 oz copper pour under the exposed thermal pad area of the package (if present on the chosen footprint variant) to improve power dissipation.
Estimated: Common pitfalls with the UCC3809P-2 include (1) confusing the SS/SD pin polarity - it is active-low shutdown, so leaving it floating enables the device; tie it to VREF through a 100 kOhm resistor to disable until soft-start, (2) exceeding 1 mA loading on the VREF pin reduces reference accuracy and can pull VDD below UVLO, (3) forgetting that the UCC3809-2 (this P-2 suffix) needs VDD > 15V to start, not the 8V threshold, and (4) using too-low current-sense resistor values which forces the CS pin to trip below the design peak current due to propagation delay in the PWM comparator. Always bench-verify the actual peak current against your design calculation using a current probe on the primary MOSFET source.
Informations de conformité
Per TI UCC3809-2 product page: RoHS compliant, lead-free finish, halogen-free. Not AEC-Q100 qualified - the industrial UCC2809P-2 (-40 C to +85 C) is the closest grade for non-automotive harsh environments. For AEC-Q100 qualified primary-side PWM controllers, see TI's UCC28C43-Q1 or UCC24612-Q1 families instead.
