SLUSAQ9B December   2011  – December 2015 UC1875-SP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and 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
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  CLKSYNC
      2. 8.3.2  E/AOUT
      3. 8.3.3  CS+
      4. 8.3.4  FREQSET
      5. 8.3.5  DELSETA-B, DELSETC-D
      6. 8.3.6  EA-
      7. 8.3.7  EA+
      8. 8.3.8  GND
      9. 8.3.9  OUTA - OUTD
      10. 8.3.10 PWRGND
      11. 8.3.11 RAMP
      12. 8.3.12 SLOPE
      13. 8.3.13 SOFTSTART
      14. 8.3.14 VC
      15. 8.3.15 VIN
      16. 8.3.16 VREF
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Undervoltage Lockout Section
      2. 9.1.2 Synchronizing the Oscillator
      3. 9.1.3 Syncing to External TTL/CMOS
      4. 9.1.4 Delay Blocks and Output Stages
      5. 9.1.5 Output Switch Orientation
      6. 9.1.6 Fault/Soft Start
      7. 9.1.7 Slope/Ramp Pins
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  Phase-Shifted Fundamentals
        2. 9.2.2.2  Circuit Schematic and Description
        3. 9.2.2.3  Initial Conditions (Time: t = t(0))
        4. 9.2.2.4  Right Leg Resonant Transition Interval (Time: t(0) < t < t(1))
        5. 9.2.2.5  Clamped Freewheeling Interval (Time: t(1) < t < t(2))
        6. 9.2.2.6  Left Leg Transition Interval (Time: t(2) < t < t(3))
        7. 9.2.2.7  Power Transfer Interval (Time: t(3) < t < t(4))
        8. 9.2.2.8  Switch Turn Off (Time: t(4))
        9. 9.2.2.9  Resonant Tank Considerations
        10. 9.2.2.10 Resonant Circuit Limitations
        11. 9.2.2.11 Stored Inductive Energy
        12. 9.2.2.12 Resonant Circuit Summary
        13. 9.2.2.13 Stored Energy Requirements
        14. 9.2.2.14 Minimum Primary Current
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Ground (GND)
      2. 11.1.2 Bias Supply (VCC)
      3. 11.1.3 Feedback Traces
      4. 11.1.4 Compensation Components
      5. 11.1.5 Traces and Ground Planes
      6. 11.1.6 Current Transformer
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
Supply voltage (VC, VIN) 20 V
Output current, source or sink DC 0.5 A
Pulse (0.5 µs) 3 A
Analog inputs (Pins 1, 2, 3, 4, 5, 6, 7, 15, 16, 17, 18, 19) –0.3 5.3 V
Maximum junction temperature, JTmax 150
Thermal Resistance, RθJC(top) J package 7 °C/W
W package 5.4
FK package 5.6
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) Pin references are to 20-pin packages. All voltages are with respect to ground. Currents are positive into, negative out of the device terminals.

7.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±1000 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
Supply Voltage Vin 10.75 12 18 V

7.4 Thermal Information

THERMAL METRIC(1) UC1875-SP UNIT
J (CDIP) FK (LCCC) W (CFP)
20 PINS 28 PINS 24 PINS
RθJC(top) Junction-to-case (top) thermal resistance 6.2 8.2 4.8 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

7.5 Electrical Characteristics

–55°C < TA < 125°C. VC = VIN = 12 V, R(FREQSET) = 12 kΩ, C(FREQSET) = 330 pF, R(SLOPE) = 12 kΩ, C(RAMP) = 200 pF,
C(DELAYSET A-B) = C(DELAYSET C-D) = 0.01 µF, I(DELAYSET A-B) = I(DELAYSET C-D) = –500 µA, TA = TJ, unless otherwises stated.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
UNDERVOLTAGE LOCKOUT
Start threshold 10.75 11.75 V
UVLO hysteresis 0.5 1.25 2 V
SUPPLY CURRENT
IIN Startup VIN = 8 V, VC = 20 V, R(SLOPE) open,
I(DELAY) = 0		 150 600 μA
IC Startup VIN = 8 V, VC = 20 V, R(SLOPE) open,
I(DELAY) = 0		 10 100 µA
IIN 30 44 mA
IC 15 30 mA
VOLTAGE REFERENCE
Output voltage TJ = 25°C 4.92 5 5.08 V
Line regulation 11 V < VIN < 20 V 1 10 mV
Load regulation IVREF = –10 mA 5 20 mV
Total variation Line, Load, Temperature 4.9 5.1 V
Noise Voltage 10 Hz to 10 kHz 50 µVrms
Long Term Stability TJ = 125°C, 1000 hours 2.5 mV
Short circuit current VREF = 0 V, TJ = 25°C 60 mA
ERROR AMPLIFIER
Offset voltage 5 15 mV
Input bias current 0.6 3 μA
AVOL 1 V < V(E/AOUT) < 4 V 60 90 dB
CMMR 1.5 V < VCM < 5.5 V 75 95 dB
PSRR 11 V < VIN < 20 V 85 100 dB
Output sink current V(E/AOUT) = 1 V 1 2.5 mA
Output source current I(E/AOUT) = 4 V –1.3 –0.5 mA
Output voltage high I (E/AOUT) = –0.5 mA 4 4.7 5 V
Output voltage low I(E/AOUT) = 1 mA 0 0.5 1 V
Unity Gain BW See (7) 01 device 5 MHz
02 device 7
Slew rate See (7) 6 11 V/μs
PWM COMPARATOR
RAMP offset voltage TJ = 25°C(2) 1.3 V
Zero phase shift voltage See (3) 0.55 0.9 V
PWM phase shift (1)(6) V(E/AOUT) > (Ramp Peak + Ramp Offset) 01 device 98% 99.5% 102%
02 device 96% 100% 104%
V(E/AOUT) < Zero Phase Shift Voltage 0% 0.5% 2%
Output skew (1) (6) V(E/AOUT) > 1 V 5 ±20 ns
Ramp to output delay (5) (7) 65 125
OSCILLATOR
Initial accuracy TA = 25°C 01 device 0.85 1 1.15 MHz
02 device 0.85 1 1.19
Voltage stability 11 V < VIN < 20 V 0.2% 2%
Total variation Line, Temperature 0.8 1.2 MHz
Sync pin threshold TJ = 25°C 3.8 V
Clock out peak TJ = 25°C 4.3 V
Clock out low TJ = 25°C 3.3 V
Clock out pulse width R(CLOCKSYNC) = 3.9 kΩ 30 100 ns
Maximum frequency (6) R(FREQUEST) = 5 kΩ 2 MHz
RAMP GENERATOR/SLOPE COMPENSATION
Ramp current, minimum I(SLOPE) = 10 µA, V(FREQSET) = VREF –11 –14 µA
Ramp current, maximum I(SLOPE) = 1 mA, V(FREQSET) = VREF –0.8 –0.95 mA
Ramp valley 0 V
Ramp peak - clamping level R(FREQSET) = 100 kΩ 3.8 4.1 5 V
CURRENT LIMIT
Input bias VCS+ = 3 V 2 5 μA
Threshold voltage 2.4 2.5 2.6 V
Delay to output (7) 85 150 ns
SOFT START/RESET DELAY
Charge current V(SOFTSTART) = 0.5 V –20 –9 –3 μA
Discharge current V(SOFTSTART) = 1 V 120 230 µA
Restart threshold 4.3 4.7 V
Discharge level 300 mV
OUTPUT DRIVERS
Output low level IOUT = 50 mA 0.2 0.4 V
Output high level IOUT = –50 mA 1.5 2.5 V
DELAY SET
Delay set voltage I(DELAY) = –500 µA 2.3 2.4 2.6 V
Delay time (7) I(DELAY) = –250 µA (4) 150 250 600 ns
(1) Phase shift percentage (0% = 0 , 100% = 180 ) is defined as UC1875-SP eq_note1_lus230.gif where is the phase shift, and and T are defined in Figure 1. At 0% phase shift, is the output skew.
(2) Ramp offset voltage has a temperature coefficient of about –4 mV/°C.
(3) The zero phase shift voltage has a temperature coefficient of about –2 mV/°C.
(4) Delay time can be programmed via resistors from the delay set pins to ground. Delay time = UC1875-SP q_625x10_lusaq9.gif .
Where I(DELAY) = UC1875-SP q_delay_set_lusaq9.gif. The Recommended range for I(DELAY) is 25 µA ≤ I(DELAY) ≤ 1 mA.
(5) Ramp delay to output time is defined in Figure 1
(6) Not production tested at –55·C.
(7) Not production tested.
UC1875-SP duty_cycle1_lusaq9.gif
Duty Cycle = t/T, Period = T
TDHL (A to C) = TDHL (B to D) = Φ
Figure 1. Phase Shift, Output Skew and Delay Time Definitions
UC1875-SP duty_cycle2_lusaq9.gif Figure 2. Ramp to Delay Output