KA78RH33RTM Linear Voltage Regulator 3.3V 800mA Equivalent & Substitute Parts

Part Overview

The KA78RH33RTM is a linear voltage regulator IC manufactured by onsemi, delivering a fixed 3.3V output at 800mA in a TO-252-3 (DPAK) surface mount package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The regulator provides positive fixed output with integrated over-current and over-temperature protection, suitable for applications requiring stable 3.3V power delivery from input sources up to 15V.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	800mA
Input Voltage (Max)	15V
Dropout Voltage	1.4V @ 800mA
Quiescent Current	10mA
PSRR	55dB (120Hz)
Protection Features	Over Current, Over Temperature
Operating Temperature	-25°C to 125°C
Package	TO-252-3 (DPAK)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitute parts for the KA78RH33RTM are selected based on strict electrical and mechanical compatibility criteria. The following parameters must align for direct substitution:

Output voltage: 3.3V fixed
Package type: TO-252-3 (DPAK, 2 Leads + Tab)
Surface mount configuration
Input voltage rating: 15V maximum
Protection features: Over-current and over-temperature capability
Output current capability: minimum 800mA

Substitutes are grouped into two categories based on output current rating:

Category 1: 800mA Output Current – Direct pin-compatible replacements with identical current specifications (LD1117DT33CTR, LD1117DT33TR, LM1117DT-3.3/NOPB, LM1117DTX-3.3/NOPB, LM1117IDT-3.3/NOPB, LM1117IDTX-3.3/NOPB, TLV1117-33CKVURG3)

Category 2: 1A Output Current – Pin-compatible upgrades with higher current capability (AZ1117D-3.3TRE1, LMS8117ADT-3.3/NOPB, LMS8117ADTX-3.3/NOPB)

Parameter Comparison

Part Number	Manufacturer	Output Current	Dropout Voltage	Quiescent Current	PSRR (120Hz)	Operating Temp	Product Status	RoHS Status
KA78RH33RTM	onsemi	800mA	1.4V @ 800mA	10mA	55dB	-25°C to 125°C	Obsolete	Not specified
AZ1117D-3.3TRE1	Diodes Incorporated	1A	1.25V @ 1A	10mA	75dB	-40°C to 125°C	Active	ROHS3 Compliant
LD1117DT33CTR	STMicroelectronics	800mA	1.3V @ 800mA	10mA	75dB	-40°C to 125°C	Active	ROHS3 Compliant
LD1117DT33TR	STMicroelectronics	800mA	1.2V @ 800mA	10mA	75dB	0°C to 125°C	Active	ROHS3 Compliant
LM1117DT-3.3/NOPB	Texas Instruments	800mA	1.2V @ 800mA	5mA	75dB	0°C to 125°C	Active	ROHS3 Compliant
LM1117DTX-3.3/NOPB	Texas Instruments	800mA	1.2V @ 800mA	5mA	75dB	0°C to 125°C	Active	ROHS3 Compliant
LM1117IDT-3.3/NOPB	Texas Instruments	800mA	1.2V @ 800mA	5mA	75dB	-40°C to 125°C	Active	ROHS3 Compliant
LM1117IDTX-3.3/NOPB	Texas Instruments	800mA	1.2V @ 800mA	5mA	75dB	-40°C to 125°C	Active	ROHS3 Compliant
LMS8117ADT-3.3/NOPB	Texas Instruments	1A	1.25V @ 1A	5mA	60-75dB	0°C to 125°C	Active	ROHS3 Compliant
LMS8117ADTX-3.3/NOPB	Texas Instruments	1A	1.25V @ 1A	5mA	60-75dB	0°C to 125°C	Active	ROHS3 Compliant
TLV1117-33CKVURG3	Texas Instruments	800mA	1.3V @ 800mA	10mA	75dB	0°C to 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts are active products with ROHS3 compliance, providing long-term availability and regulatory alignment for new designs. The KA78RH33RTM's obsolete status necessitates migration to active alternatives.

For direct 800mA replacement with extended temperature range: LM1117IDT-3.3/NOPB or LM1117IDTX-3.3/NOPB (Texas Instruments) maintain the -40°C to 125°C operating range and are widely available.

For direct 800mA replacement with standard temperature range: LD1117DT33CTR (STMicroelectronics) or LM1117DT-3.3/NOPB (Texas Instruments) are suitable for 0°C to 125°C applications with improved dropout voltage performance.

For higher current capability (1A): AZ1117D-3.3TRE1 (Diodes Incorporated), LMS8117ADT-3.3/NOPB, or LMS8117ADTX-3.3/NOPB (Texas Instruments) provide 1A output current in the same TO-252-3 package, enabling design flexibility for increased load requirements.

All substitutes maintain identical package geometry (TO-252-3 DPAK), pin configuration, and protection features (over-current and over-temperature), ensuring direct PCB compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can I use a 1A rated regulator as a direct replacement for the 800mA KA78RH33RTM?

A: Yes. The 1A-rated parts (AZ1117D-3.3TRE1, LMS8117ADT-3.3/NOPB, LMS8117ADTX-3.3/NOPB) are pin-compatible and maintain identical TO-252-3 package geometry. They provide higher current capability without affecting circuit operation at 800mA or below. No PCB modifications are required.

Q: What is the difference between the LM1117 variants (DT, DTX, IDT, IDTX)?

A: The suffix indicates packaging format: DT = Tube packaging, DTX = Cut Tape & Digi-Reel, IDT = Tube packaging (industrial grade), IDTX = Cut Tape & Digi-Reel (industrial grade). All variants are electrically identical with the same TO-252-3 package and pin configuration. Selection depends on procurement and assembly requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed active substitute parts carry ROHS3 compliance certification, meeting current regulatory requirements for new product designs and manufacturing.

Q: What is the significance of dropout voltage differences between substitutes?

A: Dropout voltage determines the minimum input-to-output voltage differential required for regulation. Lower dropout voltage (1.2V vs. 1.4V) allows operation with lower input voltages or provides better efficiency in power-constrained applications. For most standard applications, the difference is not critical.

Q: Can I substitute the KA78RH33RTM with LD1117DT33TR if my application operates below 0°C?

A: No. LD1117DT33TR is rated 0°C to 125°C. For applications requiring -25°C operation, use LM1117IDT-3.3/NOPB or LM1117IDTX-3.3/NOPB, which maintain the -40°C to 125°C range.

Q: Are there inventory considerations for selecting a substitute?

A: Yes. Inventory levels vary significantly. LM1117DTX-3.3/NOPB (25,400 units), LD1117DT33CTR (124,512 units), and AZ1117D-3.3TRE1 (174,050 units) offer substantial stock availability for production requirements.

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