AMS1117CD

Part: AMS1117-3.3 — Advanced Monolithic Systems

Type: Low Dropout (LDO) Linear Voltage Regulator, Fixed 3.3 V

Description: 1 A low dropout fixed 3.3 V linear regulator with 1.3 V max dropout at 0.8 A, 1.5% on-chip reference trim and current/thermal limiting.

Operating Conditions:

• Supply voltage: output set by V(IN) − V(OUT) differential of up to 12 V (line regulation tested at 1.5 V ≤ V(IN) − V(OUT) ≤ 12 V); absolute max input 15 V
• Operating junction temperature: -40 to 125 °C
• Output current: up to 1 A
• Output capacitor: 22 μF solid tantalum recommended for stability

Absolute Maximum Ratings:

• Max input voltage: 15 V
• Operating junction temperature: -40 °C to 125 °C
• Storage temperature: -65 °C to +150 °C
• Lead temperature (soldering, 25 sec): 265 °C
• Power dissipation: internally limited

Key Specs:

• Output voltage (V(IN) = 4.8 V, T(J) = 25 °C): 3.300 V typ, 3.251–3.349 V
• Line regulation: 0.5 mV typ, 10 mV max (1.5 V ≤ V(IN) − V(OUT) ≤ 12 V)
• Load regulation (V(IN) = 4.75 V, 0 ≤ I(OUT) ≤ 0.8 A): 3 mV typ, 15 mV max
• Dropout voltage (I(OUT) = 0.8 A, 1% output change): 1.1 V typ, 1.3 V max
• Current limit (V(IN) − V(OUT) = 1.5 V): 900 mA min, 1,100 mA typ, 1,500 mA max
• Quiescent current (V(IN) − V(OUT) = 1.5 V): 5 mA typ, 11 mA max
• Ripple rejection (120 Hz, I(OUT) = 1 A, V(IN) = 4.75 V): 60 dB min, 72 dB typ
• Thermal resistance junction-to-case: 15 °C/W max (all packages)

Features:

• Fixed 3.3 V output (family also offers adjustable, 1.5 V, 1.8 V, 2.5 V, 2.85 V, 5.0 V)
• Output current of 1 A
• Operates down to 1 V dropout
• Line regulation 0.2% max, load regulation 0.4% max (adjustable version)
• On-chip trimming of the reference to 1.5%
• Short-circuit current limiting and thermal shutdown (junction temperature above 165 °C)
• No protection diodes needed on the adjust pin
• RoHS compliant

Applications:

• High efficiency linear regulators
• Post regulators for switching supplies
• 5 V to 3.3 V linear regulator
• Battery chargers
• Active SCSI terminators
• Power management for notebooks
• Battery powered instrumentation

Package:

• SOT-223 (3-lead)
• TO-252 (DPAK)
• 8L SOIC

• Three Terminal Adjustable or Fixed Voltages* 1.5V, 1.8V, 2.5V, 2.85V, 3.3V and 5.0V
• Output Current of 1A
• High Efficiency Linear Regulators
• Post Regulators for Switching Supplies
• 5V to 3.3V Linear Regulator
• Operates Down to 1V Dropout
• Battery Chargers
• Line Regulation: 0.2% Max.
• Active SCSI Terminators
• Load Regulation: 0.4% Max.
• Power Management for Notebook
• SOT-223, TO-252 and SO-8 package available
• Battery Powered Instrumentation

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

(Note 1)

Power Dissipation

Internally limited

Input Voltage

15V

Operating Junction Temperature Range

Control Section

-40 ° C to 125 ° C

Power Transistor

-40 ° C to 125 ° C

Storage temperature

• 65 ° C to +150 ° C

Soldering information

Lead Temperature (25 sec)

265 ° C

Thermal Resistance

SO-8 package

ϕ JA= 160 ° C/W

TO-252 package

ϕ JA= 80 ° C/W

SOT-223 package

ϕ JA= 90 ° C/W*

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.

Table 1.

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.

TO-252 PLASTIC PACKAGE (D)

3 LEAD SOT-223 PLASTIC PACKAGE

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted (Continued).