SLUS872E January   2009  – February 2019 UC1842A-SP , UC1844A-SP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Electrical Characteristics (Radiation-Improved Devices)
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 UVLO
      2. 8.3.2 Reference
      3. 8.3.3 Totem-Pole Output
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Oscillator
        2. 9.2.2.2 Current Sensing and Limiting
        3. 9.2.2.3 Error Amplifier
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Feedback Traces
      2. 11.1.2 Input/Output Capacitors
      3. 11.1.3 Compensation Components
      4. 11.1.4 Traces and Ground Planes
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.6 Electrical Characteristics (Radiation-Improved Devices)

VCC = 15 V, RT = 10 kΩ, CT = 3.3 nF, TA = TJ = –55°C to 125°C (unless otherwise noted) (1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
REFERENCE
Output voltage TJ = 25°C, IO = 1 mA 4.94 5 5.06 V
Line regulation VCC = 12 to 25 V 6 20 mV
Load regulation IL = 1 to 20 mA 6 25 mV
Total output variation Over line, load, and temperature 4.9 5.1 V
Output noise voltage 10 Hz ≤ ƒ ≤ 10 kHz, TJ = 25°C 50 μV
Short-circuit output current –30 –100 –180 mA
OSCILLATOR
Initial accuracy TJ = 25°C 47 52 57 kHz
Voltage stability VCC = 12 to 25 V 0.2% 1%
Temperature stability TJ = –55°C to 125°C 5%
Amplitude VRT/CT peak to peak 1.7 V
Discharge current(5) TJ = 25°C, VRT/CT = 2 V 7.8 8.3 8.8 mA
VRT/CT = 2 V 7.5 8.8
ERROR AMPLIFIER
Input voltage VComp = 2.5 V 2.45 2.50 2.55 V
Input bias current –0.3 –1 μA
Open-loop voltage gain VO = 2 to 4 V 65 90 dB
Unity-gain bandwidth TJ = 25°C(2) 0.7 1 MHz
PSRR VCC = 12 to 25 V 60 70 dB
Output sink current VFB = 2.7 V, VComp = 1.1 V 2 6 mA
Output source current VFB = 2.3 V, VComp = 5 V –0.5 –0.8 mA
High-level output voltage VFB = 2.3 V, RL = 15 kΩ to ground 5 6 V
Low-level output voltage VFB = 2.7 V, RL = 15 kΩ to VREF 0.7 1.1 V
CURRENT SENSE
Gain(3)(4) 2.85 3 3.15 V/V
Maximum input signal VComp = 5 V(3) 0.9 1 1.1 V
PSRR VCC = 12 to 25 V(3) 70 dB
Input bias current –2 –10 μA
Delay to output VISENSE = 0 to 2 V (2) 150 300 ns
OUTPUT
Output low-level voltage ISINK = 20 mA 0.1 0.4 V
ISINK = 200 mA 1.5 2.2
Output high-level voltage ISOURCE = 20 mA 13 13.5 V
ISOURCE = 200 mA 12 13.0
Rise time CL = 1 nF, TJ = 25°C(2) 50 150 ns
Fall time CL = 1 nF, TJ = 25°C(2) 50 150 ns
UVLO saturation VCC = 5 V, ISINK = 10 mA 0.7 1.2 V
UNDERVOLTAGE LOCKOUT
Start threshold 7.8 8.4 9 V
Minimum operation voltage after turnon 7 7.6 8.2 V
PWM
Maximum duty cycle 94% 96% 100%
Minimum duty cycle 0%
TOTAL STANDBY CURRENT
Start-up current 0.3 0.5 mA
Operating supply current VFB = VISENSE = 0 V 11 17 mA
VCC Zener voltage ICC = 25 mA 30 34 V
(1) Electrical table applicable to radiation-improved 5962-8670409 device type
(2) Parameters ensured by design and/or characterization, if not production tested.
(3) Parameter measured at trip point of latch with VFB = 0 V.
(4) Gain defined as: G = ΔVComp/ΔVISENSE; VISENSE = 0 to 0.8 V.
(5) This parameter is measured with RT = 10 kΩ to VREF. This contributes approximately 300 μA of current to the measurement. The total current flowing into the RT or CT pin will be approximately 300 μA higher than the measured value.