MIC5205-3.3

Part: MIC5205, Micrel Type: 150mA Low-Noise LDO Regulator

Key Specs:

• Output Current: 150mA (Guaranteed)
• Dropout Voltage: 17mV (typical at light loads), 165mV (typical at 150mA)
• Ground Current: 600µA (typical at 100mA output)
• Initial Accuracy: Better than 1%
• Output Noise: 260 nV/√Hz (typical)
• Quiescent Current (shutdown): 0.01 µA (typical)
• Current Limit: 320 mA (typical)

Features:

• Ultra-low-noise output
• High output voltage accuracy
• Guaranteed 150mA output
• Low quiescent current
• Low dropout voltage
• Extremely tight load and line regulation
• Very low temperature coefficient
• Current and thermal limiting
• Reverse-battery protection
• "Zero" off-mode current
• Logic-controlled electronic enable

Applications:

• Cellular telephones
• Laptop, notebook, and palmtop computers
• Battery-powered equipment
• PCMCIA VCC and VPP regulation/switching
• Consumer/personal electronics
• SMPS post-regulator/dc-to-dc modules
• High-efficiency linear power supplies

Package:

• SOT-23-5: No dimensions specified

• Ultra-low-noise output
• High output voltage accuracy
• Guaranteed 150mA output
• Low quiescent current
• Low dropout voltage
• Extremely tight load and line regulation
• Very low temperature coefficient
• Current and thermal limiting
• Reverse-battery protection
• "Zero" off-mode current
• Logic-controlled electronic enable

• Cellular telephones
• Laptop, notebook, and palmtop computers
• Battery-powered equipment
• PCMCIA VCC and VPP regulation/switching
• Consumer/personal electronics
• SMPS post-regulator/dc-to-dc modules
• High-efficiency linear power supplies

MIC5205-x.xBM5/YM5 MIC5205BM5/YM5 Fixed Voltages Adjustable Voltages

VIN = VOUT + 1V; IL = 100µA; CL = 1.0µF; VEN ≥ 2.0V; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.

Notes:

• 1. Exceeding the absolute maximum rating may damage the device.
• 2. The device is not guaranteed to function outside its operating rating.
• 3. The maximum allowable power dissipation at any TA (ambient temperature) is PD(max) = (TJ(max) TA) ⎟ ⎝JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The ⎝JA of the MIC5205-xxBM5 (all versions) is 220°C/W mounted on a PC board (see "Thermal Considerations" section for further details).
• 4. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
• 5. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
• 6. Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential.
• 7. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of the load current plus the ground pin current.
• 8, Thermal regulation is defined as the change in output voltage at a time "t" after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 150mA load pulse at VIN = 16V for t = 10ms.

The MIC5205 is designed to provide 150mA of continuous current in a very small package. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation:

$$P_{D(max)} = \frac{\left(T_{J(max)} - T_{A}\right)}{\theta_{JA}}$$

$T_{J(max)}$ is the maximum junction temperature of the die, 125°C, and TA is the ambient operating temperature. $\theta_{JA}$ is layout dependent; Table 1 shows examples of junction-toambient thermal resistance for the MIC5205.

Table 1. SOT-23-5 Thermal Resistance

The actual power dissipation of the regulator circuit can be determined using the equation:

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

Substituting PD(max) for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. For example, when operating the MIC5205-3.3BM5 at room temperature with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows:

$$P_{D(max)} = \frac{(125^{\circ}C - 25^{\circ}C)}{220^{\circ}C/W}$$

$$P_{D(max)} = 455mW$$

The junction-to-ambient thermal resistance for the minimum footprint is 220°C/W, from Table 1. The maximum power dissipation must not be exceeded for proper operation. Using the output voltage of 3.3V and an output current of 150mA, the maximum input voltage can be determined. From the Electrical Characteristics table, the maximum ground current for 150mA output current is 2500µA or 2.5mA.

$$455\text{mW} = (V_{\text{IN}} - 3.3\text{V}) \ 150\text{mA} + V_{\text{IN}} \cdot 2.5\text{mA}$$

$455\text{mW} = V_{\text{IN}} \times 150\text{mA} - 495\text{mW} + V_{\text{IN}} \cdot 2.5\text{mA}$
$950\text{mW} = V_{\text{IN}} \times 152.5\text{mA}$

$$V_{IN(max)} = 6.23V$$

Therefore, a 3.3V application at 150mA of output current can accept a maximum input voltage of 6.2V in a SOT-23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the Regulator Thermals section of Micrel's Designing with Low-Dropout Voltage Regulators handbook.