MIC4043 MICREL | Alldatasheet

Document overview

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Technical content

Features

  • Ideal for 1.8V switching converters
  • Low-voltage operation 400mV maximum saturation over operating temperature range
  • Easy to use voltage in, current out
  • 2% voltage tolerance over operating temperature range

Applications

  • Optically isolated low-volage power supplies
  • Low-voltage discrete regulator control Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

Pin Number Pin Name Pin Function 1 IN Input: Supply voltage input. 2 SNK Sink (Output): NPN open collector output.

3 GND Ground

4 FB Feedback (Input): 1.245V feedback input from external voltage-divider network. Pin Configuration FB GND SNK Part Identification IN RBxx MIC4043

Ordering Information

Part Number Marking Voltage Tolerance Configuration Temperature Range Package MIC4043BM4 RBAD 1.245V 1% Open Collector –40°C to +85°C SOT-143 Absolute Maximum Ratings (Note 1) ESD Rating, Note 3 Operating Ratings (Note 2)

Electrical Characteristics

TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted Parameter Condition Min Typ Max Units Reference Voltage 1.245 V Reference Voltage Tolerance ±1% ±2 % Supply Current I SNK = 0mA 35 65 µA 70 µA Transconductance 1mA < I SNK < 15mA 3.5 150 S ∆ISINK/∆VIN 2 S Output Transistor I SNK = 15mA 160 250 mV Saturation Voltage 400 mV Output Leakage V SNK = 5V, output transistor off 0.5 µA 1 µA Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Test Circuits IN R A 33k C FB 2700pF 50Ω GND FB SNKOUT RETURN MIC4043 Floating Bench Supply R R OUTPUT R A A A * Compensation element Do Not Ground! Analyzer V TUO 1R2 R V8.1k 27k 33 V5.2k 33k 33 V3.3k 02k 33 Test Circuit 1. Compensation (Bode Plot) Circuit IN1k 33k C1* 1000pF C2* 2700pF GND FB SNKOUT RETURN MIC4043Supply * Compensation components Test Circuit 2. Transient Response Circuit

Transient Response 1a. 1.8V Output Without Compensation VINVREGVOUT Transient Response 1b. 1.8V Output With Compensation VINVREGVOUT Transient Response 2a. 2.5V Output Without Compensation VINVREGVOUT Transient Response 2b. 2.5V Output With Compensation VINVREGVOUT Transient Response 3a. 3.3V Output Without Compensation VINVREGVOUT Transient Response 3b. 3.3V Output With Compensation VINVREGVOUT

1.245V GND MIC4043 Functional Description The MIC4043 combines a Gm amplifier, precision 1.245V reference, and a pass transistor in a single package. The operation of the MIC4043 is similar to conventional shunt regulators such as the industry standard ’431. In a closed loop system, the MIC4043 maintains the desired feedback voltage at the FB pin by sinking current onto the SNK pin proportional to the error voltage at the FB pin. The ratio of sink current to error voltage is the transconductance of the device. Reference The MIC4043 uses a high-side reference. External voltage dividers providing feedback to the MIC4043 will be inverted when compared to those used with ’431-equivalent devices. Behavior The external feedback voltage is compared to the internal high-side 1.245V reference. If the feedback voltage, V FB , is less than VIN – VREF , the amplifier provides no drive to the sink transistor. If the feedback voltages is greater than V IN – VREF , the amplifier drives the pass transistor which sinks current to ground.

Package Information

0.150 (0.0059) 0.089 (0.0035)8° 0.400 (0.016) TYP 3 PLACES 2.50 (0.098) 2.10 (0.083) 1.40 (0.055) 1.20 (0.047) 0.950 (0.0374) TYP 3.05 (0.120) 2.67 (0.105) 0.800 (0.031) TYP 1.12 (0.044) 0.81 (0.032) 0.10 (0.004) 0.013 (0.0005) DIMENSIONS: MM (INCH) 0.41 (0.016) 0.13 (0.005) CL CL SOT-143 (M4)

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated