SNVS867 June   2014 LM3633

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Control Bank Mapping
        1. 7.3.1.1 High-Voltage Control Banks (A and B)
        2. 7.3.1.2 Low-Voltage Control Banks (C, D, E, F, G, and H)
      2. 7.3.2 Pattern Generator
      3. 7.3.3 PWM Input
      4. 7.3.4 HWEN Input
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 High-Voltage LED Control
        1. 7.4.1.1  High-Voltage Boost Converter
        2. 7.4.1.2  High-Voltage Current Sinks (HVLED1, HVLED2 and HVLED3)
        3. 7.4.1.3  High-Voltage Current String Biasing
        4. 7.4.1.4  Boost Switching-Frequency Select
        5. 7.4.1.5  Automatic Switching Frequency Shift
        6. 7.4.1.6  Brightness Register Current Control
          1. 7.4.1.6.1 8-Bit Control (Preferred)
          2. 7.4.1.6.2 11-Bit Control
        7. 7.4.1.7  PWM Control
          1. 7.4.1.7.1 PWM Input Frequency Range
          2. 7.4.1.7.2 PWM Input Polarity
          3. 7.4.1.7.3 PWM Zero Detection
        8. 7.4.1.8  Start-up/Shutdown Ramp
        9. 7.4.1.9  Run-Time Ramp
        10. 7.4.1.10 High-Voltage Control A/B Ramp Select
        11. 7.4.1.11 LED Current Mapping Modes
        12. 7.4.1.12 Exponential Mapping
          1. 7.4.1.12.1 8-Bit Code Calculation
          2. 7.4.1.12.2 11-Bit Code Calculation
        13. 7.4.1.13 Linear Mapping
          1. 7.4.1.13.1 8-Bit Code Calculation
          2. 7.4.1.13.2 11-Bit Code Calculation
      2. 7.4.2 Low-Voltage LED Control
        1. 7.4.2.1  Integrated Charge Pump
        2. 7.4.2.2  Charge Pump Disabled
        3. 7.4.2.3  Automatic Gain
        4. 7.4.2.4  Automatic Gain (Flying Capacitor Detection)
        5. 7.4.2.5  1X Gain
        6. 7.4.2.6  2X Gain
        7. 7.4.2.7  Low-Voltage Current Sinks (LVLED1 to LVLED6)
        8. 7.4.2.8  Low-Voltage LED Biasing
        9. 7.4.2.9  Brightness Register Current Control
        10. 7.4.2.10 LED Current Mapping Modes
        11. 7.4.2.11 Exponential Mapping
        12. 7.4.2.12 Linear Mapping
        13. 7.4.2.13 Start-up/Shutdown Ramp
        14. 7.4.2.14 Run-Time Ramp
      3. 7.4.3 Low-Voltage LED Pattern Generator
        1. 7.4.3.1 Delay Time
        2. 7.4.3.2 Rise Time
        3. 7.4.3.3 Fall Time
        4. 7.4.3.4 High Period
        5. 7.4.3.5 Low Period
        6. 7.4.3.6 Low-Level Brightness
        7. 7.4.3.7 High-Level Brightness
      4. 7.4.4 Fault Flags/Protection Features
        1. 7.4.4.1 Open LED String (HVLED)
        2. 7.4.4.2 Shorted LED String (HVLED)
        3. 7.4.4.3 Open LED (LVLED)
        4. 7.4.4.4 Shorted LED (LVLED)
        5. 7.4.4.5 Overvoltage Protection (Inductive Boost)
        6. 7.4.4.6 Current Limit (Inductive Boost)
        7. 7.4.4.7 Current Limit (Charge Pump)
      5. 7.4.5 I2C-Compatible Interface
        1. 7.4.5.1 Start and Stop Conditions
        2. 7.4.5.2 I2C-Compatible Address
        3. 7.4.5.3 Transferring Data
    5. 7.5 Register Descriptions
      1. 7.5.1 Pattern Generator Registers
  8. Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Boost Converter Maximum Output Power (Boost)
          1. 8.2.2.1.1 Peak Current Limited
          2. 8.2.2.1.2 Output Voltage Limited
        2. 8.2.2.2 Boost Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Schottky Diode Selection
        5. 8.2.2.5 Input Capacitor Selection
        6. 8.2.2.6 Maximum Output Power (Charge Pump)
        7. 8.2.2.7 Charge Pump Flying Capacitor Selection
        8. 8.2.2.8 Charge Pump Output Capacitor Selection
        9. 8.2.2.9 Charge Pump Input Capacitor Selection
      3. 8.2.3 Application Performance Plots
    3. 8.3 Initialization Set Up
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines (Boost)
      1. 10.1.1 Boost Output Capacitor Placement
      2. 10.1.2 Schottky Diode Placement
      3. 10.1.3 Inductor Placement
      4. 10.1.4 Boost Input Capacitor Placement
    2. 10.2 Layout Guidelines (Charge Pump)
      1. 10.2.1 Flying Capacitor (CP) Placement
      2. 10.2.2 Output Capacitor (CPOUT) Placement
      3. 10.2.3 Charge Pump Input Capacitor Placement
    3. 10.3 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 Applications and Implementation

8.1 Application Information

The LM3633 provides a complete high-performance, high-voltage LED and low-voltage-indicator LED lighting solution for mobile handsets. The LM3633 is highly configurable and can support the high-voltage LED configurations summarized in Table 36. The LM3633 utilizes internal ramp-time generators to provide smooth 11-bit high-voltage LED dimming while requiring only an 8-bit command from the host controller. The LM3633EVM is available with GUI software to aid understanding of the LM3633 operation.

Table 36. Supported High-Voltage LED Configurations

NUMBER OF HIGH-VOLTAGE LED STRINGS MAXIMUM NUMBER OF SERIES HIGH-VOLTAGE LEDs
3 6
2 10
1 10

8.2 Typical Application

Application_Schematic.pngFigure 23. LM3633 Simplified Schematic

Table 37. Application Circuit Component List

COMPONENT MANUFACTURER VALUE PART NUMBER SIZE CURRENT/VOLTAGE RATING (Resistance)
L TDK 10 µH VLF302512MT-100M 2.5mm x 3.0mm x 1.2mm 620 mA/0.25 mΩ
COUT 1 µF C2012X5R1H105 0805 50 V
CIN 2.2 µF C1005X5R1A225 0402 10 V
CPOUT/CP 1 µF C1005X5R1A105 0402 10 V
WLED 312WBCW(A) 0603 30 mA/3.3 V (typ.)
Diode On-Semi NSR0240V2T1G SOD-523 40 V, 250 mA

8.2.1 Design Requirements

Table 38. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Full-scale current setting 20.2 mA
Minimum Input Voltage 3.0 V
LED series/parallel configuration 6s3p
LED maximum forward voltage (Vf) 3.5 V
Efficiency 80

The designer needs to know the following

  • Full-scale current setting
  • Minimum input voltage
  • LED series/parallel configuration
  • LED maximum Vf voltage
  • LM3633 Efficiency for LED configuration

The full-scale current setting, number of led strings, number of series LEDs, and minimum input voltage are needed in order to calculate the peak input current. This information guides the designer to make the appropriate inductor selection for the application.

The LM3633 boost converter output voltage (VOUT) is calculated as follows: number of series LEDs * Vƒ + 0.4V

The LM3633 boost converter output current (IOUT) is calculated as follows: number of parallel LED strings * Full-scale current

The LM3633 peak input current (I IN_PK) is calculated as follows: VOUT * IOUT / Minimum VIN / Efficiency

Equation 11. eq01_new_snosc2.gif

8.2.2 Detailed Design Procedure

8.2.2.1 Boost Converter Maximum Output Power (Boost)

Maximum output power of the LM3633 is governed by two factors: the peak current limit (ICL = 880 mA min), and the maximum output voltage (VOVP). When the application causes either of these limits to be reached it is possible that the proper current regulation and matching between LED current strings is not met.

8.2.2.1.1 Peak Current Limited

In the case of a peak current limited situation, the NFET switch turns off for the remainder of the switching period when the inductor current peak hits the LM3633 current limit. If this happens each switching cycle the LM3633 regulates the inductor current peak instead of the headroom across the current sinks. This can result in the dropout of the boost output connected current sinks, and the LED current dropping below its programmed level.

The peak current in a boost converter is dependent on the value of the inductor, total LED current in the boost (IOUT), the boost output voltage (VOUT) (which is the highest voltage LED string + VHR ), the input voltage (VIN), the switching frequency, and the efficiency (Output Power/Input Power). Additionally, the peak current is different depending on whether the inductor current is continuous during the entire switching period (CCM), or discontinuous (DCM) where it goes to 0 before the switching period ends. For Continuous Conduction Mode the peak inductor current is given by:

Equation 12. 30200329.gif

For Discontinuous Conduction Mode the peak inductor current is given by:

Equation 13. 30200330.gif

To determine which mode the circuit is operating in (CCM or DCM) it is necessary to perform a calculation to test whether the inductor current ripple is less than the anticipated input current (IIN). If ΔIL is less than IIN then the device operates in CCM. If ΔIL is greater than IIN then the device is operating in DCM.

Equation 14. 30200331.gif

Typically at currents high enough to reach the LM3633 peak current limit, the device operates in CCM.

The following figures show the output current and voltage derating for a 10-µH and a 22-µH inductor. These plots take equations (1) and (2) from above and plot VOUT and IOUT with varying VIN, a constant peak current of 880 mA (ICL_MIN), 500-kHz switching frequency, and a constant efficiency of 85%. Using these curves gives a good design guideline on selecting the correct inductor for a given output power requirement. A 10-µH inductor is typically a smaller device with lower on resistance, but the peak currents are higher. A 22-µH inductor provides for lower peak currents, but to match the DC resistance of a 10-µH inductor, a larger-sized device is required.

C052_SNVS867.pngFigure 24. Maximum Output Power (22 µH)
C051_SNVS867.pngFigure 25. Maximum Output Power (10 µH)

8.2.2.1.2 Output Voltage Limited

In the case of a output voltage limited situation (VOUT = VOVP), when the boost output voltage hits the LM3633 OVP threshold, the NFET turns off and stays off until the output voltage falls below the hysteresis level (typically 1 V below the OVP threshold). This results in the boost converter regulating the output voltage to the programmed OVP threshold (16 V, 24 V, 32 V, or 40 V), causing the current sinks to go into dropout. The default OVP threshold is set at 16 V. For LED strings higher than typically 4 series LEDs, the OVP has to be programmed higher after power-up or after a HWEN reset.

8.2.2.2 Boost Inductor Selection

The boost circuit operates using a 4.7-μH to 22-μH inductor. The inductor selected must have a saturation current greater than the peak operating current.

8.2.2.3 Output Capacitor Selection

The LM3633 inductive boost converter requires a 1.0-µF (X5R or X7R) ceramic capacitor to filter the output voltage. The voltage rating of the capacitor depends on the selected OVP setting. For the 16-V setting a 16-V capacitor must be used. For the 24-V setting a 25-V capacitor must be used. For the 32-V setting, a 35-V capacitor must be used. For the 40-V setting a 50-V capacitor must be used. Pay careful attention to the capacitor tolerance and DC bias response. For proper operation the degradation in capacitance due to tolerance, DC bias, and temperature, should stay above 0.4 µF. This might require placing two devices in parallel in order to maintain the required output capacitance over the device operating range, and series LED configuration.

8.2.2.4 Schottky Diode Selection

The Schottky diode must have a reverse breakdown voltage greater than the LM3633 maximum output voltage (see Overvoltage Protection (Inductive Boost) section). Additionally, the diode must have an average current rating high enough to handle the LM3633 maximum output current, and at the same time the diode peak current rating must be high enough to handle the peak inductor current. Schottky diodes are required due to their lower forward voltage drop (0.3 V to 0.5 V) and their fast recovery time.

8.2.2.5 Input Capacitor Selection

The input capacitor on the LM3633 filters the voltage ripple due to the switching action of the inductive boost and the capacitive charge-pump doubler. A ceramic capacitor of at least 2.2-µF (X5R or X7R) must be used to filter the input voltage.

8.2.2.6 Maximum Output Power (Charge Pump)

The maximum output power available from the LM3633 charge pump is determined by the maximum output voltage available from the charge pump. In 1X gain the charge pump operates in Pass Mode so the voltage at CPOUT tracks VIN (less the drop across the charge-pump pass switch). In this case the maximum output power is given as:

Equation 15. 30200393.gif

where RCP is the resistance from VIN to CPOUT and ILVLED_TOTAL is the maximum programmed current in the LVLED strings.

In 2X gain the voltage at CPOUT (VCPOUT_2X) is regulated to typically 4.4 V. In this case the maximum output power is given by:

Equation 16. 30200394.gif

Both equations assume there is sufficient headroom at the top side of the low-voltage current sinks to ensure the LED current remains in regulation (VHR_LV) in the electrical table.

8.2.2.7 Charge Pump Flying Capacitor Selection

The charge pump flying capacitor must quickly charge up to the input voltage and then supply the current to the output every switching cycle (1 MHz). This fast switching action requires a 1.0-µF (X5R or X7R) ceramic capacitor connected to the C+ and C– pins with a low inductive connection.

8.2.2.8 Charge Pump Output Capacitor Selection

The charge pump output capacitor filters the switched charge from the flying capacitor every switching cycle (1 MHz). This fast switching action requires a 1.0-µF (X5R or X7R) ceramic capacitor connected to the CPOUT pin with a low-inductive connection.

8.2.2.9 Charge Pump Input Capacitor Selection

The input capacitor for the LM3633 charge pump is the same one used for the LM3633 inductive boost converter (see Input Capacitor Selection).

8.2.3 Application Performance Plots

VIN = 3.6 V, VLED = 3.2 V @ 20 mA, Typical Application Circuit, TA = 25°C, Full-Scale Current = 20.2 mA unless otherwise specified. Efficiency is VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are (ΔILED_MAX/ILED_AVE). See Table 37.
C004_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 26. Efficiency vs VIN, Three String
C010_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 28. Efficiency vs VIN, Dual String
C016_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 30. Efficiency vs VIN, Single String
C003_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 32. Efficiency vs VIN, Three String
C009_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 34. Efficiency vs VIN, Dual String
C015_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 36. Efficiency vs VIN, Single String
C002_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 38. Efficiency vs VIN, Three String
C008_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 40. Efficiency vs VIN, Dual String
C014_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 42. Efficiency vs VIN, Single String
C022_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 44. Efficiency vs ILED
C028_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 46. Efficiency vs ILED
C021_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 48. Efficiency vs ILED
C027_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 50. Efficiency vs ILED
C020_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 52. Efficiency vs ILED
C026_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 54. Efficiency vs ILED
C070_SNVS867.png
ILED = 20 mA
Figure 56. HVLED Matching vs VIN, Temp
C074_SNVS867.png
Exponential Mapping
Figure 58. HVLED Current vs Code
C076_SNVS867.png
Linear Mapping
Figure 60. HVLED Matching vs Code
C077_SNVS867.png
Linear Mapping
Figure 62. LVLED Matching vs Code
C073_SNVS867.pngFigure 64. LVLED Current vs Current Sink Headroom Voltage
C081_SNVS867.png
50% Duty Cycle
Figure 66. LED Current Ripple vs fPWM
C080_SNVS867.png
1x Gain
Figure 68. Charge Pump Output Short Circuit Current Limit vs VIN

Startup_3p6_Linear.png
3x6 LEDs
Figure 70. Start-up Response
VIN_Step_1M.png
Typical Application Circuit 3 x 6 LEDs
Figure 72. Line Step Response
C007_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 27. Efficiency vs VIN, Three String
C013_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 29. Efficiency vs VIN, Dual String
C019_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 31. Efficiency vs VIN, Single String
C006_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 33. Efficiency vs VIN, Three String
C012_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 35. Efficiency vs VIN, Dual String
C018_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 37. Efficiency vs VIN, Single String
C005_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 39. Efficiency vs VIN, Three String
C011_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 41. Efficiency vs VIN, Dual String
C017_SNVS867.png
Top to Bottom: 1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Figure 43. Efficiency vs VIN, Single String
C025_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 45. Efficiency vs ILED
C031_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 47. Efficiency vs ILED
C024_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 49. Efficiency vs ILED
C030_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 51. Efficiency vs ILED
C023_SNVS867.png
Top to Bottom: 3x3, 3x4, 3x5, 3x6 (LEDs)
Figure 53. Efficiency vs ILED
C029_SNVS867.png
Top to Bottom: 2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Figure 55. Efficiency vs ILED
C071_SNVS867.png
ILED = 20 mA
Figure 57. LVLED Matching vs VIN, Temp
C075_SNVS867.png
Exponential Mapping
Figure 59. HVLED Matching vs Code
C078_SNVS867.png
Exponential Mapping
Figure 61. LVLED Matching vs Code
C072_SNVS867.png
Figure 63. HVLED Current vs Current Sink Headroom Voltage
C082_SNVS867.pngFigure 65. Closed Loop Current Limit vs VIN
C079_SNVS867.png
2x Gain
Figure 67. Charge Pump Output Short Circuit Current Limit vs VIN
C083_SNVS867.png
Pattern Generator Enabled on LVLED1, LVLED2, LVLED3
Figure 69. Idle State Supply Current
PWM_Step.png
D = 30% To 90% ƒPWM = 10 kHz
Figure 71. Response to Step Change in PWM Input Duty Cycle

8.3 Initialization Set Up

Table 39 shows the minimum number of register writes required for a two-parallel, seven-series LED configuration. This example uses the default settings for ramp times (2048 μsec), mapping mode (exponential) and full-scale current (20.2 mA). In this mode of operation the LM3633 controls the brightness LSBs to ramp between the 8-bit MSB brightness levels providing 11-bit dimming while requiring only 8-bit commands from the host controller.

Table 39. Control Bank A, 8-Bit Control, Two-String, Seven Series LED Configuration Example

REGISTER NAME ADDRESS DATA DESCRIPTION
HVLED Current Sink Output Configuration 0x10 0x04 HVLEDs 1 and 2 assigned to Control Bank A
HVLED Current SInk Feedback Enables 0x28 0x03 Enable feedback on HVLEDs 1 and 2, disable feedback on HVLED 3
Boost Control 0x2D 0x04 OVP = 32V, ƒsw = 500 kHz
Control Bank Enabled 0x2B 0x01 Enable Control Bank A
Control A Brightness LSB 0x40 0x00 Control A Brightness LSB written only once
Control A Brightness MSB 0x41 User Value Control A Brightness MSB updated as required

Table 40 shows the minimum number of register writes required for a two-parallel, six-series LED configuration with PWM Enabled. This example uses the default settings for ramp times (2048 μsec), mapping mode (exponential) and full-scale current (20.2 mA). In this mode of operation the host controller must update both the brightness LSB and MSB registers whenever a brightness change is required.

Table 40. Control Bank A, 11-Bit Control, Two-String, Six Series LED Configuration Example

REGISTER NAME ADDRESS DATA DESCRIPTION
HVLED Current Sink Output Configuration 0x10 0x04 HVLEDs 1 and 2 assigned to Control Bank A
HVLED Current SInk Feedback Enables 0x28 0x03 Enable feedback on HVLEDs 1 and 2, disable feedback on HVLED 3
Boost Control 0x2D 0x03 OVP = 24V, ƒsw = 1 MHz
PWM Configuration 0x2F 0x0D PWM Zero Detect = Enabled, PWM Polarity = Active HIgh, Control B PWM = Disabled, Control A PWM = Enabled
Control Bank Enabled 0x2B 0x01 Enable Control Bank A
Control A Brightness LSB 0x40 User Value Control A Brightness LSB written as required
(NOTE: The Brightness LSB change does not take effect until the Brightness MSB register is written.)
Control A Brightness MSB 0x41 User Value Control A Brightness MSB updated as required(1)
(1) Anytime the Brightness LSB is changed the Brightness MSB must be written for the Brightness LSB change to take effect.)

Table 41 shows the minimum number of register writes required for five low-voltage indicator LEDs. This example uses the default settings for ramp times (2048 μs), mapping mode (exponential) and charge pump and can be combined with either Table 39 or Table 40 above paying careful attention to the Brightness Configuration and Control Bank Enable registers (these registers control both high-voltage and low-voltage LEDs). In this mode of operation the host controller must update both Controls C and F brightness whenever a low-voltage LED brightness change is required. In this example the indicator LEDs is not synchronized due to the time delay between configuration of the Control C and Control F brightness settings. If synchronization of the indicator LED timing is required the user must enable the Control Bank after writing all Control Bank brightness registers.

Table 41. Control Bank A Enable with Control Bank C and Control Bank F Low-Voltage LED Configuration Example

REGISTER NAME ADDRESS DATA DESCRIPTION
LVLED Current Sink Output Configuration 0x11 0x20 LVLEDs 1, 2, and 3 assigned to Control Bank C
LVLED 4, 5 assigned to Control Bank F, LVLED 6 assigned to Control Bank H
Control C Full-Scale Current Setting 0x22 0x00 Set Full-Scale current to 5 mA
Control F Full-Scale Current Setting 0x25 0x00 Set Full-Scale current to 5 mA
LVLED Current SInk Feedback Enables 0x29 0x1F Enable feedback on LVLEDs 1, 2, 3, 4, 5; LVLED 6 disabled
Control Bank Enable 0x2B 0x25 Enable LVLED Control Banks F and C with HVLED Control Bank A
(If synchronization of indicator LEDs is required enable Control Bank after Control Banks C and F Brightness register configuration)
Control C Brightness 0x44 User Value Control C Brightness written as required
Control F Brightness 0x47 User Value Control F Brightness updated as required

Table 42 shows the minimum number of register writes required to configure the pattern generator for all six low-voltage indicator LEDs. This pattern sequences through all six indicator LEDs using a uniform delay time of 196.608 ms.

Table 42. Low Voltage LED Pattern Generator Configuration Example

REGISTER NAME ADDRESS DATA DESCRIPTION
LVLED Current Sink Output Configuration 0x11 0x36 All low-voltage LED current sinks assigned to independent Control Banks
Control C Start-up/Shutdown Ramp Time 0x14 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control D Start-up/Shutdown Ramp Time 0x15 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control E Start-up/Shutdown Ramp Time 0x16 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control F Start-up/Shutdown Ramp Time 0x17 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control G Start-up/Shutdown Ramp Time 0x18 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control H Start-up/Shutdown Ramp Time 0x19 0x33 Set Start-up and Shutdown Ramp time to 1.049 seconds
Control C//D/E Ramp Time 0x1C 0x33 Set Ramp Up/Down Transition time to 1.049 seconds
Control F/G/H Ramp Time 0x1D 0x33 Set Ramp Up/Down Transition time to 1.049 seconds
Control C Full-Scale Current Setting 0x22 0x00 Set Full-Scale current to 5 mA
Control D Full-Scale Current Setting 0x23 0x00 Set Full-Scale current to 5 mA
Control E Full-Scale Current Setting 0x24 0x00 Set Full-Scale current to 5 mA
Control F Full-Scale Current Setting 0x25 0x00 Set Full-Scale current to 5 mA
Control G Full-Scale Current Setting 0x26 0x00 Set Full-Scale current to 5 mA
Control H Full-Scale Current Setting 0x27 0x00 Set Full-Scale current to 5 mA
Control C Brightness 0x44 0xA5 Control C Brightness
Control D Brightness 0x45 0xA5 Control D Brightness
Control E Brightness 0x46 0xA5 Control E Brightness
Control F Brightness 0x47 0xA5 Control F Brightness
Control G Brightness 0x48 0xA5 Control G Brightness
Control H Brightness 0x49 0xA5 Control H Brightness
Control C Pattern Generator Delay Time 0x50 0x00 Set Control C Delay time to 16.384 ms
Control D Pattern Generator Delay Time 0x60 0x0C Set Control D Delay time to 212.992 ms
Control E Pattern Generator Delay Time 0x70 0x18 Set Control E Delay time to 409.6 ms
Control F Pattern Generator Delay Time 0x80 0x24 Set Control F Delay time to 606.208 ms
Control G Pattern Generator Delay Time 0x90 0x30 Set Control G Delay time to 802.816 ms
Control H Pattern Generator Delay Time 0xA0 0x3C Set Control H Delay time to 999.424 ms
Control C Pattern Generator Low Time 0x51 0x3A Set Control C Low Time to 950.27 ms
Control D Pattern Generator Low Time 0x61 0x3A Set Control D Low Time to 950.27 ms
Control E Pattern Generator Low Time 0x71 0x3A Set Control E Low Time to 950.27 ms
Control F Pattern Generator Low Time 0x81 0x3A Set Control F Low Time to 950.27 ms
Control G Pattern Generator Low Time 0x91 0x3A Set Control G Low Time to 950.27 ms
Control H Pattern Generator Low Time 0xA1 0x3A Set Control H Low Time to 950.27 ms
Control C Pattern Generator High Time 0x52 0x40 Set Control C High Time to 1507.33 ms
Control D Pattern Generator High Time 0x62 0x40 Set Control D High Time to 1507.33 ms
Control E Pattern Generator High Time 0x72 0x40 Set Control E High Time to 1507.33 ms
Control F Pattern Generator High Time 0x82 0x40 Set Control F High Time to 1507.33 ms
Control G Pattern Generator High Time 0x92 0x40 Set Control G High Time to 1507.33 ms
Control H Pattern Generator High Time 0xA2 0x40 Set Control H High Time to 1507.33 ms
Control C Pattern Generator Low-Level Brightness 0x53 0x01 Set Control C Low-Level Brightness
Control D Pattern Generator Low-Level Brightness 0x63 0x01 Set Control D Low-Level Brightness
Control E Pattern Generator Low-Level Brightness 0x73 0x01 Set Control E Low-Level Brightness
Control F Pattern Generator Low-Level Brightness 0x83 0x01 Set Control F Low-Level Brightness
Control G Pattern Generator Low-Level Brightness 0x93 0x01 Set Control G Low-Level Brightness
Control H Pattern Generator Low-Level Brightness 0xA3 0x01 Set Control H Low-Level Brightness
Pattern Generator Enables 0x2C 0xFC Enable Control Bank C/D/E/F/G/H Pattern Generators
Control Bank Enables 0x2B 0xFC Enable Control Banks C/D/E/F/G/H