TL494 Reference Tables, Pins & Specifications

Pin reference

Signal names, electrical functions and connection guidance

PDIP-16

Physical pin numbers16 pins

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TL494 pin functions and connections
Signal	Type	Function & connection
1IN+	Error amplifier 1 noninverting input	A higher voltage than 1IN− demands shorter output pulses. Connection guidance Ground in the open-loop pulse example.
1IN−	Error amplifier 1 inverting input	Reference input for the first error amplifier. Connection guidance Connect to REF14 in the open-loop example.
FEEDBACK	PWM feedback node	Shared error-amplifier output and PWM control node; increasing it suppresses pulses. Connection guidance Leave externally unconnected in this DTC-controlled demonstration. Do not short this node to ground while an amplifier is trying to drive it HIGH.
DTC	Dead-time control	Increasing this input shortens the conduction interval independently of the error amplifiers. Connection guidance Connect to the wiper of a 10 kΩ potentiometer between REF14 and GND. Start with the wiper near REF for outputs OFF, then reduce it slowly.
CT	Oscillator capacitor	Charges and discharges to form the internal timing ramp. Connection guidance Connect 1 nF to GND; keep the loop short.
RT	Oscillator resistor	Sets the timing capacitor charging current. Connection guidance Connect 100 kΩ to GND.
GND	Common return	Reference for control, oscillator and supply. Connection guidance Join bypass, timing and scope returns.
C1	Output transistor 1 upper contact	Uncommitted output contact; the example uses it as a pulled-up switching output. Connection guidance Connect 4.7 kΩ to +12 V and a high-impedance scope channel. Output goes LOW when its transistor conducts.
E1	Output transistor 1 lower contact	Return-side contact of output transistor 1. Connection guidance Ground in this sinking-output example.
E2	Output transistor 2 lower contact	Return-side contact of output transistor 2. Connection guidance Ground in this sinking-output example.
C2	Output transistor 2 upper contact	Second uncommitted output contact. Connection guidance Connect its own 4.7 kΩ to +12 V and the second scope channel.
VCC	Control supply	Supplies the controller and reference regulator. Connection guidance Apply +12 V with 100 nF and local bulk decoupling to GND.
OUTPUT CTRL	Output mode selection	LOW selects simultaneous single-ended operation; REF selects alternating push-pull operation. Connection guidance Tie to GND in the main example. Change modes only with power removed. This mode pin is not intended as a PWM switching input.
REF	Five-volt reference output	Regulated reference for bias and control networks. Connection guidance Bypass with 100 nF; connect the control potentiometer and amplifier inverting inputs. Reference current is limited; it does not supply motors or power loads.
2IN−	Error amplifier 2 inverting input	Reference input for the second amplifier. Connection guidance Connect to REF14 in the open-loop example.
2IN+	Error amplifier 2 noninverting input	A higher voltage than 2IN− demands shorter pulses. Connection guidance Ground in the open-loop example.

Operating conditions

TL494C selected variants

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
Control supply	7–40 V	12 V bench circuit
Ambient temperature	0 to +70°C	C grade; I grade is a different ordering choice
Oscillator frequency	1–300 kHz	Recommended range
Timing resistor	1.8–500 kΩ	RT to ground
Timing capacitor	0.47–10000 nF	CT to ground
Amplifier input common mode	−0.3 V to VCC−2 V	Do not exceed the valid range
Output current	Up to 200 mA per transistor	Check voltage drop, thermal conditions and external limits

Output current capability does not mean the IC includes a safe power-stage current limiter.

Reference and feedback

Specified test conditions

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
REF at 1 mA	4.75–5.25 V; 5 V typical	Specified supply and temperature conditions
Reference external load	Up to 10 mA available for bias	Includes the potentiometer and other external loads
Feedback input sink	0.3 mA minimum, 0.7 mA typical	FEEDBACK = 0.7 V
PWM zero-duty threshold	3.4 V typical, 4.5 V maximum	Feedback control test
Error amplifier offset	2 mV typical, 10 mV maximum	Specified electrical test
Error amplifier gain	80 dB typical, 70 dB minimum	Specified load and output range

The reference is for control bias; it is not a general-purpose supply rail.

Output modes

Configure OUTPUT CTRL as a fixed logic level

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Pin 13 to GND	Single-ended / simultaneous	Both outputs can conduct during the same oscillator cycle
Pin 13 to REF	Push-pull / alternating	Each output receives every other oscillator cycle
Single-ended frequency	fOUT ≈ fOSC	Same period per channel
Push-pull frequency	fOUT ≈ fOSC / 2	Twice the period per channel
Grounded DTC	Maximum allowed conduction	Internal blanking still prevents an ideal 100% duty
Increasing DTC	Shorter conduction pulses	Around 3.3 V can command zero duty under specified conditions

At the pulled-up C outputs used here, transistor conduction appears as a LOW pulse.

Resistor-loaded pulse circuit

No external power stage

Manufacturer-referenced values9 parameters

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Parameter	Value	Conditions / notes
VCC12 / GND7	+12 V / common GND	100 nF and local bulk bypass
REF14	100 nF to GND	Feeds both inverting amplifier inputs and 10 kΩ pot
Amplifier inputs	1 / 16 to GND; 2 / 15 to REF	Keeps the error amplifiers from demanding shutdown
FEEDBACK3	No external connection	Internal amplifier/bias network still determines its voltage
DTC4	Potentiometer wiper	Pot ends REF and GND; start HIGH
CT5 / RT6	1 nF / 100 kΩ to GND	Nominal 10 kHz design equation
Mode13	GND	Simultaneous operation
Outputs	E1-9 / E2-10 to GND	C1-8 and C2-11 each pull up to +12 V through 4.7 kΩ
Measurement	High-impedance two-channel scope	Observe each C output relative to GND

Do not attach a motor or transformer to this demonstration; output loads are deliberately small.

Frequency and example calculations

First-order design values

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
Oscillator	1/(100000 Ω × 1 nF) = 10 kHz	Nominal approximation
Oscillator period	100 µs	Inverse of 10 kHz
Single-ended output period	100 µs	Same as oscillator
Push-pull per-output period	200 µs	5 kHz on each output
Approximate pulled-up load	12 V / 4.7 kΩ = 2.55 mA	Ignoring switch voltage drop
Worst resistor power at continuous ON	12² / 4700 ≈ 31 mW	Use suitable voltage and power ratings
Potentiometer reference load	5 V / 10 kΩ = 0.5 mA	Plus other reference loads

Real timing varies with component tolerances and oscillator characteristics.

Layout and integration

Keep control wiring distinct from a power stage

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Timing loop	Short CT/RT ground return	Keep away from switching nodes
Reference bypass	Close to REF14 and GND7	Avoid loading the reference excessively
Supply bypass	Close to VCC12 and GND7	Add suitable local bulk capacitance
Feedback compensation	Application-specific	Needed for stable closed-loop regulation
Output polarity	LOW at C when sinking	An external follower connection has a different waveform
Power switch drive	Separate design task	Check gate charge, edge speed and protection

A clear bench waveform alone does not validate a complete switching converter.

Package and stress limits

TL494CN · PDIP-16

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
PDIP	TL494CN · N package	16 pins, 2.54 mm pitch
SOIC	TL494CDR · D package	16 pins, 1.27 mm pitch
Supply stress	41 V absolute maximum	Normal operation maximum is 40 V
Output current stress	250 mA absolute maximum	Recommended current maximum is 200 mA with conditions
Storage	−65 to +150°C	Unpowered
Outputs C/E	Keep the manufacturer pin names	The current revision describes the switching output implementation separately from legacy terminology

Use the selected orderable and datasheet revision rather than mixing limits from different manufacturers.