VIPER318LDTR from STMicroelectronics, in a SO-16. 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 and MOSFET source, carrying both the internal MOSFET source and the bias current return; all bias component grounds must tie to a trace to this pin, kept separate from the pulsed current return.
2	N.C.	unconnected	Not connected; when designing the PCB this pin can be soldered to GND.
3	VCC	power_in	Controller supply with an external storage capacitor across VCC and GND; the pin is internally tied to the high-voltage current source that charges VCC at startup, and a 0.1 µF bypass capacitor placed close to the IC is recommended.
4	N.A.	passive	Not available for user; mechanically connected to the controller die pad, and it is highly recommended to connect it to GND to improve noise immunity.
5	UVP	input	Undervoltage protection input: the IC is disabled when VUVP stays below VUVP_th (0.4 V typ.) for more than tUVP_DEB (30 ms typ.), and it resumes after tUVP_REST (30 ms typ.) once VUVP rises above the threshold; leave open if the function is not required.
6	OVP	input	Overvoltage protection input: when VOVP exceeds VOVP_th (4 V typ.) for more than tOVP_DEB (250 µs typ.) the PWM is disabled in auto-restart for tOVP_REST (500 ms typ.); connect to GND if the function is not required.
7	FB	input	Direct feedback, the inverting input of the internal transconductance E/A referenced to 1.2 V with respect to GND; the E/A is disabled if FB is connected to GND.
8	COMP	output	Output of the internal E/A that requires a compensation network to GND for loop stability; in secondary feedback the COMP pin is driven directly by the optocoupler to set the DRAIN peak current setpoint.
9	N.C.	unconnected	Not connected; must be left floating to maintain a safe clearance distance.
10	N.C.	unconnected	Not connected; must be left floating to maintain a safe clearance distance.
11	N.C.	unconnected	Not connected; must be left floating to maintain a safe clearance distance.
12	N.C.	unconnected	Not connected; must be left floating to maintain a safe clearance distance.
13	DRAIN	passive	MOSFET drain, from which the internal high-voltage current source charges the VCC capacitor at startup; these pins are tied to the internal metal pad for heat dissipation and PCB copper under them lowers junction-to-ambient thermal resistance.
14	DRAIN	passive	MOSFET drain, from which the internal high-voltage current source charges the VCC capacitor at startup; these pins are tied to the internal metal pad for heat dissipation and PCB copper under them lowers junction-to-ambient thermal resistance.
15	DRAIN	passive	MOSFET drain, from which the internal high-voltage current source charges the VCC capacitor at startup; these pins are tied to the internal metal pad for heat dissipation and PCB copper under them lowers junction-to-ambient thermal resistance.
16	DRAIN	passive	MOSFET drain, from which the internal high-voltage current source charges the VCC capacitor at startup; these pins are tied to the internal metal pad for heat dissipation and PCB copper under them lowers junction-to-ambient thermal resistance.

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	SO-16
Category	Power Management (PMIC)
Pins	16

Electrical characteristics

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

Parameter	Symbol	Min	Typ	Max	Unit	Conditions	Page
Drain-to-source (ground) voltage	VDS			800	V		4
Pulsed drain current	IDRAIN			3	A	pulse-width limited by SOA	4
VCC voltage	VCC	-0.3		30.5	V		4
FB voltage	VFB	-0.3		5	V	AMR valid when VCC ≥ 5 V; otherwise VCC + 0.3 V	4
Power dissipation	PTOT			1	W	Tamb < 50°C	4
Junction temperature operating range	TJ	-40		150	°C		4
Storage temperature	TSTG	-55		150	°C		4
Thermal resistance junction to case, SO16N	RTH-JC			10	°C/W	dissipated power = 1 W; FR4 board, minimum copper area	4
Thermal resistance junction to ambient, SO16N	RTH-JA			120	°C/W	dissipated power = 1 W; FR4 board, minimum copper area	4
Thermal resistance junction to case, SO16N	RTH-JC			5	°C/W	dissipated power = 1 W; FR4 board, 100 mm² (0.155² inch) Cu, 35 µm	4
Thermal resistance junction to ambient, SO16N	RTH-JA			85	°C/W	dissipated power = 1 W; FR4 board, 100 mm² (0.155² inch) Cu, 35 µm	4
Breakdown voltage	VBVDSS	800			V	IDRAIN = 1 mA, VCOMP = VGND, TJ = 25°C	5
Static drain-source ON-resistance	RDS(on)			3.5	Ω	IDRAIN = 400 mA, TJ = 25°C	5
Static drain-source ON-resistance	RDS(on)			7	Ω	IDRAIN = 400 mA, TJ = 125°C	5
VCC operating voltage range	VCC	4.5		30	V		6
VCC startup threshold	VCcon	7.5	8	8.5	V		6
HV current source turn-on threshold	VCson	4	4.25	4.5	V	VCC falling	6
UVLO	VCcoff	3.75	4	4.25	V		6
VCC charging current at startup	ICH1	0.5	1	1.5	mA	VDRAIN = 100 V, VCC ≤ 1 V	6
VCC charging current	ICH2	7.6	8.8	10	mA	VFB > VFB_REF, VDRAIN = 100 V, 1 V < VCC < VCCon	6
Startup resistor	RG	36	45	54	MΩ	VFB > VFB_REF, VDRAIN = 400 V, VDRAIN = 600 V	6
Operating supply current, switching	ICC		1.5	2	mA	VDS = 150 V, VCOMP = 1.2 V, FOSC = 60 kHz	6
Reference voltage	VFB_REF	1.175	1.2	1.225	V		7
E/A disable voltage	VFB_DIS	150	180	210	mV		7
Pull-up current	IFB_PULL UP	0.9	1	1.1	µA		7
Trans conductance	GM	400	550	700	µA/V	VCOMP = 1.5 V, VFB > VFBREF	7
Max. source current	ICOMP1	75	100	125	µA	VCOMP = 1.5 V, VFB = 0.5 V	7
Max. sink current	ICOMP2	75	100	125	µA	VFB = 2 V, VCOMP = 1.5 V	7
Dynamic resistance	RCOMP(DYN)	13	15	17	kΩ	VCOMP = 2.7 V, VFB = GND	7
Current limitation threshold	VCOMPH	2.75	3.1	3.45	V		7
PFM threshold	VCOMPL	0.6	0.8	1	V		7
ΔVCOMP/ΔIDRAIN, VIPER318	HCOMP	3.2	3.5	3.8	V/A		7
Drain current limitation, VIPER318	IDLIM	810	850	890	mA	TJ = 25°C	7
Drain current limitation, VIPER318	IDLIM	765	850	935	mA	Note (1): measured at Vin = 100 Vdc, flyback, 1.5 mH primary inductance	7
Power coefficient IDLIM_TYP2 x FOSC_TYP, VIPER318L tolerance	I2f	-10		10	%	VIPER318L; nominal 43.4 A2·kHz	7
Drain current limitation at light load, VIPER318	IDlim_PFM	100	130	160	mA	TJ = 25°C, VCOMP = VCOMPL; Note (1): measured at Vin = 100 Vdc, flyback, 1.5 mH primary inductance	7
Overload delay time	tOVL	45	50	55	ms		8
Max. overload delay time	tOVL_max			100	ms	when in pulse skipping	8
Soft-start time	tSS	5	8	11	ms		8
Minimum turn-on time	tON_MIN	250	300	350	ns	VCC = 9 V, VCOMP = 1 V, VFB = VFB_REF	8
Restart time after fault	tRESTART	0.625	1	1.375	s		8
UVP threshold	VUVP_th	0.38	0.4	0.42	V	VCC = 9 V, VCOMP = 1 V, VFB = VFB_REF	8
Debounce time before UVP tripping	tUVP_DEB	18.75	30	41.25	ms		8
Debounce time for restoring normal operation from UVP	tUVP_REST	18.75	30	41.25	ms		8
Quiescent current during UVP	Iq_DIS		0.25	0.35	mA	Not switching, VFB > VFB_REF	8
Overvoltage protection threshold	VOVP_th	3.85	4	4.15	V	VCC = 9 V, VCOMP = 1 V, VFB = VFB_REF	8
Debounce time before OVP tripping	tOVP_DEB	156	250	344	µs		8
Restart time after overvoltage protection tripping	tOVP_REST	312	500	688	ms		8
Switching frequency, VIPER31*L	FOSC	54	60	66	kHz	TJ = 25°C	8
Min. switching frequency	FOSC MIN	13.5	15	16.5	kHz	TJ = 25°C	8
Modulation depth (±7·FOSC)	FD	-7		7	%	as a multiple of FOSC; parameter assured by design and characterization	8
Max. duty cycle	DMAX		70	80	%	parameter assured by design and characterization	8
Thermal shutdown temperature threshold	TSD		150	160	°C	parameter assured by design and characterization	8

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 VCC capacitor at startup. The pins are mechanically connected to the internal metal PAD of the MOSFET to help heat dissipation. On the PCB, some copper areas under these pins	3

CAD (KiCad official)

Symbol: VIPER318LDTR
Footprint: Package_SO:SOIC-16_3.9x9.9mm_P1.27mm
3D model: SO-16 (KiCad packages3D, STEP)
3D model files: viper318ldtr-etched.step / viper318ldtr-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); viper318ldtr.step / viper318ldtr.glb are the bare package body.

Provenance

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

Datasheet: STMicroelectronics datasheet (40 pp, sha256 200c56a12395fdf1, retrieved 2026-10-31, tier: manufacturer)
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).

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VIPER318LDTR

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