AMS1117-3.3

Part: AMS1117 series (Manufacturer not specified)

Type: Low Dropout Voltage Regulator

Key Specs:

• Output Current: 1A
• Dropout Voltage: 1.3V Max.
• Line Regulation: 0.2% Max.
• Load Regulation: 0.4% Max.
• Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 2.85V, 3.3V, 5.0V
• Input Voltage (Absolute Max): 15V
• Operating Junction Temperature Range: -40°C to 125°C

Features:

• Three Terminal Adjustable or Fixed Voltages
• High Efficiency Linear Regulators
• Operates Down to 1V Dropout
• On-chip trimming adjusts reference voltage to 1.5%
• Current limit set to minimize stress under overload conditions
• Pin compatible with other three-terminal SCSI regulators

Applications:

• Post Regulators for Switching Supplies
• Battery Chargers
• Active SCSI Terminators
• Battery Powered Instrumentation
• 5V to 3.3V Linear Regulator
• Power Management for Notebook

Package:

• SOT-223
• TO-252
• SO-8 (8L SOIC)

• • Output Current of 1A • 5V to 3.3V Linear Regulator
• • Load Regulation: 0.4% Max. • Power Management for Notebook

GENERAL DESCRIPTION

The The AMS1117 series of adjustable and fixed voltage regulators are designed to provide up to1A output current and to operate down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V, decreasing at lower load currents.

On-chip trimming adjusts the reference voltage to 1.5%. Current limit is set to minimize the stress under overload conditions on both the regulator and power source circuitry.

The AMS1117 devices are pin compatible with other three-terminal SCSI regulators and are offered in the low profile surface mount SOT-223 package, in the 8L SOIC package and in the TO-252 (DPAK) plastic package.

ORDERING INFORMATION:

^*For additional available fixed voltages contact factory.

8L SOIC Top View

• • Output Current of 1A • 5V to 3.3V Linear Regulator
• • Load Regulation: 0.4% Max. • Power Management for Notebook

GENERAL DESCRIPTION

The The AMS1117 series of adjustable and fixed voltage regulators are designed to provide up to1A output current and to operate down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V, decreasing at lower load currents.

On-chip trimming adjusts the reference voltage to 1.5%. Current limit is set to minimize the stress under overload conditions on both the regulator and power source circuitry.

The AMS1117 devices are pin compatible with other three-terminal SCSI regulators and are offered in the low profile surface mount SOT-223 package, in the 8L SOIC package and in the TO-252 (DPAK) plastic package.

ORDERING INFORMATION:

^*For additional available fixed voltages contact factory.

8L SOIC Top View

Electrical Characteristics at IOUT = 0 mA, and T^J = +25°C unless otherwise specified.

Power Dissipation Internally limited Soldering information Input Voltage 15V Lead Temperature (25 sec) 265°C

Operating Junction Temperature Range Thermal Resistance

Control Section -40°C to 125°C SO-8 package ϕ JA= 160°C/W Power Transistor -40°C to 125°C TO-252 package ϕ JA= 80°C/W

Storage temperature - 65°C to +150°C SOT-223 package ϕ JA= 90°C/W*

* With package soldering to copper area over backside ground plane or internal power plane ϕ JA can vary from 46°C/W to >90°C/W depending on mounting technique and the size of the copper area.

The AMS1117 series have internal power and thermal limiting circuitry designed to protect the device under overload conditions. However maximum junction temperature ratings of 125°C should not be exceeded under continuous normal load conditions.

Careful consideration must be given to all sources of thermal resistance from junction to ambient. For the surface mount package SOT-223 additional heat sources mounted near the device must be considered. The heat dissipation capability of the PC board and its copper traces is used as a heat sink for the device. The thermal resistance from the junction to the tab for the AMS1117 is 15°C/W. Thermal resistance from tab to ambient can be as low as 30°C/W.

The total thermal resistance from junction to ambient can be as low as 45°C/W. This requires a reasonable sized PC board with at least on layer of copper to spread the heat across the board and couple it into the surrounding air.

Experiments have shown that the heat spreading copper layer does not need to be electrically connected to the tab of the device. The PC material can be very effective at transmitting heat between the pad area, attached to the pad of the device, and a ground plane layer either inside or on the opposite side of the board. Although the actual thermal resistance of the PC material is high, the Length/Area ratio of the thermal resistance between layers is small. The data in Table 1, was taken using 1/16" FR-4 board with 1 oz. copper foil, and it can be used as a rough guideline for estimating thermal resistance.

For each application the thermal resistance will be affected by thermal interactions with other components on the board. To determine the actual value some experimentation will be necessary.

The power dissipation of the AMS1117 is equal to:

$$P_D = (V_{IN} - V_{OUT})(I_{OUT})$$

Maximum junction temperature will be equal to:

TJ = TA(MAX) + PD(Thermal Resistance (junction-to-ambient))

Maximum junction temperature must not exceed 125°C.