TL780-15KCS Equivalent & Substitute Parts

Part Overview

The TL780-15KCS is a linear voltage regulator IC manufactured by Texas Instruments, delivering a fixed positive 15V output at 1.5A in a TO-220-3 package. This device is classified as Last Time Buy, indicating limited future availability. The TL780-15KCS provides essential voltage regulation for power management applications requiring stable 15V supply with integrated protection features including over-current, over-temperature, reverse polarity, and short-circuit protection.

Alternative models are necessary due to the Last Time Buy status, which restricts long-term procurement. Substitute parts maintain electrical and mechanical compatibility while offering improved availability and, in some cases, enhanced performance characteristics.

Key Parameters

Parameter	TL780-15KCS
Output Voltage (Fixed)	15V
Output Current	1.5A
Input Voltage (Max)	30V
Voltage Dropout (Max)	2V @ 1A
PSRR	85dB (120Hz)
Operating Temperature	0°C ~ 125°C
Package / Case	TO-220-3
Protection Features	Over Current, Over Temperature, Reverse Polarity, Short Circuit
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Output voltage matching at 15V fixed
Output current capability (minimum 1.5A for direct replacement)
Package compatibility (TO-220-3 form factor)
Input voltage rating (minimum 30V tolerance)
Operating temperature range overlap (0°C ~ 125°C minimum)
Protection feature set (over-temperature and short-circuit protection required)
RoHS3 compliance

Substitute parts are categorized as follows:

MFR Recommended (Direct Replacement): Parts with identical or superior electrical specifications and Active product status, ensuring long-term availability and performance equivalence.

Parametric Equivalent: Parts meeting all critical electrical parameters with Last Time Buy status, suitable for applications where availability constraints are acceptable.

Functional Equivalent: Parts with reduced output current (1A) or modified protection features, applicable only when design margins permit current derating.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	PSRR (120Hz)	Product Status	Protection Features	Inventory
TL780-15KCS	Texas Instruments	1.5A	30V	85dB	Last Time Buy	OC, OT, RP, SC	1307 Pcs
LM7815CT/NOPB	Texas Instruments	1A	35V	70dB	Active	OC, OT, SC	3400 Pcs
LM340T-15/NOPB	Texas Instruments	1.5A	35V	80dB	Active	OT, SC	5091 Pcs
UA7815CKCSE3	Texas Instruments	1.5A	30V	78dB	Last Time Buy	OC, OT, RP, SC	2186 Pcs
L7815ACV-DG	STMicroelectronics	1.5A	35V	58dB	Active	OT, SC	4100 Pcs
L78S15CV	STMicroelectronics	2A	35V	46dB	Obsolete	OC, OT, SC	6170 Pcs
MC7815ABTG	onsemi	1A	35V	80dB	Active	OT, SC	24809 Pcs
MC7815ACTG	onsemi	1A	35V	80dB	Active	OT, SC	1989 Pcs
MC7815BTG	onsemi	1A	35V	58dB	Active	OT, SC	20100 Pcs
MC7815CTG	onsemi	1A	35V	58dB	Active	OT, SC	158550 Pcs
NCV7815BTG	onsemi	1A	35V	58dB	Obsolete	OT, SC	906 Pcs

Legend: OC = Over Current, OT = Over Temperature, RP = Reverse Polarity, SC = Short Circuit

Engineering Selection Recommendations

Tier 1 - Direct Replacement (Recommended):

LM340T-15/NOPB is the primary substitute. It maintains 1.5A output current matching the original specification, operates at 35V maximum input voltage (exceeding the 30V requirement), and holds Active product status ensuring indefinite availability. Texas Instruments manufacturing provides supply chain continuity. The 80dB PSRR is acceptable for most applications, with only 5dB reduction from the original.

Tier 2 - Parametric Equivalent:

UA7815CKCSE3 provides identical electrical performance to the TL780-15KCS, including 1.5A output current, 30V input rating, and comprehensive protection features (over-current, over-temperature, reverse polarity, short-circuit). However, Last Time Buy status limits future procurement windows. This option is suitable for immediate replacement when inventory availability is critical.

Tier 3 - Functional Equivalent (Current Derating Required):

MC7815ABTG, MC7815ACTG, MC7815BTG, and MC7815CTG are onsemi alternatives rated at 1A output current. These parts are suitable only when circuit design permits 33% current reduction from the original 1.5A specification. MC7815CTG offers the highest inventory (158,550 Pcs), providing maximum supply security. All onsemi variants maintain Active status and 35V input voltage rating.

Not Recommended:

L78S15CV (Obsolete status) and NCV7815BTG (Obsolete status) should not be selected for new designs despite available inventory. LM7815CT/NOPB (1A output) requires current derating and lacks over-current protection present in the original design.

Frequently Asked Questions (FAQ)

Q: Can LM340T-15/NOPB directly replace TL780-15KCS without circuit modification?

A: Yes. LM340T-15/NOPB maintains identical output voltage (15V), matching output current (1.5A), compatible TO-220-3 package, and exceeds input voltage rating (35V vs. 30V). Both devices are RoHS3 compliant. No circuit changes are required.

Q: What is the impact of using MC7815CTG instead of TL780-15KCS?

A: MC7815CTG reduces output current from 1.5A to 1A, representing a 33% derating. This substitution is valid only if the application circuit draws maximum 1A. The TO-220-3 package remains compatible. PSRR reduces from 85dB to 58dB, acceptable for non-audio applications. Over-current protection is not available in MC7815CTG.

Q: Why is L78S15CV listed despite Obsolete status?

A: L78S15CV is included for reference only. Its 2A output current exceeds the original 1.5A specification, but Obsolete status restricts procurement to existing inventory only. New designs should not depend on this part.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain RoHS3 compliance, matching the original TL780-15KCS certification status.

Q: What is the difference between UA7815CKCSE3 and LM340T-15/NOPB for 15V 1.5A applications?

A: Both parts deliver 1.5A at 15V in TO-220-3 packages. LM340T-15/NOPB is Active status with 35V input rating and 5091 Pcs inventory. UA7815CKCSE3 is Last Time Buy status with 30V input rating and 2186 Pcs inventory. LM340T-15/NOPB is preferred for long-term designs due to Active status.

Q: Can reverse polarity protection be sacrificed in the application?

A: The original TL780-15KCS includes reverse polarity protection. Most substitute parts (LM340T-15/NOPB, MC7815 series) do not provide this feature. If reverse polarity protection is required, UA7815CKCSE3 maintains this capability. Circuit-level protection should be evaluated if substituting to parts without this feature.

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