SLVSC76E February   2014  – May 2018 TPS92630-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application Schematic
  5. 5 Revision History
  6. 6 Description (Continued)
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Constant LED-Current Setting
      2. 10.3.2 PWM Control
      3. 10.3.3 FAULT Diagnostics
      4. 10.3.4 Short-Circuit Detection
      5. 10.3.5 Open-Load Detection
      6. 10.3.6 Thermal Foldback
    4. 10.4 Device Functional Modes
      1. 10.4.1 Thermal Information
      2. 10.4.2 Operation With V(VIN) < 5 V (Minimum V(VIN))
      3. 10.4.3 Operation With 5 V < V(VIN) < 9 V (Lower-Than-Normal Automotive Battery Voltage)
  11. 11Applications and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Applications
      1. 11.2.1 Stoplight and Taillight Application With PWM Generator
        1. 11.2.1.1 Design Requirements
        2. 11.2.1.2 Detailed Design Procedure
          1. 11.2.1.2.1 Step-by-Step Design Procedure
            1. 11.2.1.2.1.1 R(REF)
            2. 11.2.1.2.1.2 Duty Cycle
            3. 11.2.1.2.1.3 Input and Output Capacitors
        3. 11.2.1.3 PWM Dimming Application Curve
      2. 11.2.2 Simple Stop-Light and Taillight Application
        1. 11.2.2.1 Design Requirements
        2. 11.2.2.2 Detailed Design Procedure
          1. 11.2.2.2.1 Step-by-Step Design Procedure
            1. 11.2.2.2.1.1 R(REF)
            2. 11.2.2.2.1.2 R(Stop)
            3. 11.2.2.2.1.3 Input and Output Capacitors
      3. 11.2.3 Parallel Connection
        1. 11.2.3.1 Design Requirements
        2. 11.2.3.2 Detailed Design Procedure
          1. 11.2.3.2.1 Step-by-Step Design Procedure
            1. 11.2.3.2.1.1 R(REF)
            2. 11.2.3.2.1.2 Input and Output Capacitors
      4. 11.2.4 Alternate Parallel Connection
        1. 11.2.4.1 Design Requirements
        2. 11.2.4.2 Detailed Design Procedure
          1. 11.2.4.2.1 Step-by-Step Design Procedure
            1. 11.2.4.2.1.1 R(REF)
            2. 11.2.4.2.1.2 Input and Output Capacitors
      5. 11.2.5 High-Side PWM Dimming
        1. 11.2.5.1 Design Requirements
        2. 11.2.5.2 Detailed Design Procedure
          1. 11.2.5.2.1 Step-by-Step Design Procedure
            1. 11.2.5.2.1.1 Ratio of Resistors, R1 / R2
            2. 11.2.5.2.1.2 R1 and R2 Selection
            3. 11.2.5.2.1.3 Input and Output Capacitors
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Receiving Notification of Documentation Updates
    3. 14.3 Community Resources
    4. 14.4 Trademarks
    5. 14.5 Electrostatic Discharge Caution
    6. 14.6 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

10.3.5 Open-Load Detection

Detection of an open-load condition occurs when the voltage across the channel, V(VIN) – V(IOUTx), is less than the open-load detection voltage, V(OLV). When this condition is present for more than the open-load-detection deglitch (2 ms when PWM is 100% on or one PWM on-time is more than 2 ms, or seven continuous PMW duty cycles when in PWM dimming mode), the FAULT pin goes low, keeping the open channel on and turning the other channel off. With the FAULT pin tied high, all channels remain turned on. The channel recovers on removal of the open condition. Note that the device can detect an open load if the sum of the forward voltages of the LEDs in a string is close to or greater than the supply voltage on VIN.

Table 1. Fault Table(1)(2)

FAILURE MODE JUDGMENT CONDITION DIAGNOSTIC OUTPUT PINS ACTION FAULT AND FAULT_S(3) DEVICE REACTION FAILURE
REMOVED		 SELF-
CLEARING
DETECTION
VIN VOLTAGE		 CHANNEL STATUS DETECTION MECHANISM
Short circuit:
1 or several LED strings		 V(VIN)> 5 V ON V(IOUTx)< 0.9 V FAULT Pulled low Externally
pulled high		 Failing strings turned off, other channels on Toggle EN,
power cycle		 No
Floating All strings turned OFF Toggle EN,
power cycle
Single-LED short circuit:
1 or several LED strings		 V(VIN)> 9 V ON V(VSNSx)< 1.222 V FAULT_S Pulled low Externally
pulled high		 All strings stay ON Toggle EN,
power cycle		 No
Floating All strings stay ON Toggle EN,
power cycle
Open load:
1 or several LED strings		 V(VIN)> 5 V ON V(VIN) – V(IOUTx)
< 100 mV		 FAULT Pulled low Externally
pulled high		 All strings stay ON Yes
Floating Failing string stays ON, other channels turned OFF
Short to battery:
1 or several LED strings		 V(VIN)> 5 V ON or OFF V(VIN) – V(IOUTx)
< 100 mV		 FAULT Pulled low Externally
pulled high		 All strings stay ON Yes
Floating Failing string stays ON, other channels turned OFF
Thermal shutdown V(VIN)> 5 V ON or OFF Temperature > 170°C FAULT Pulled low Externally
pulled high		 All strings turned OFF Temperature < 155°C Yes
Leave open
Thermal foldback V(VIN)> 5 V ON or OFF Temperature > 110°C N/A None N/A All strings with
reduced current		 Temperature < 100°C Yes
Reference resistor
open or shorted 		V(VIN)> 5 V ON or OFF R(REF)> 57 kΩ
or
R(REF)< 350 Ω		 FAULT Pulled low N/A All strings turned OFF Toggle EN,
power cycle		 No
(1) With diagnostic pins FAULT and FAULT_S tied high externally, pullup must be strong enough to override internal pulldown.
(2) To achieve single-LED short circuit to turn off all strings, FAULT_S and FAULT pins must be connected together.
(3) Pulling FAULT and FAULT_S high externally changes the behavior of the device reaction. If not externally forced high, the device pulls the pins low based on the failure mode.