SNOSCR5D March   2013  – December 2016 LP55231


  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  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Charge Pump Electrical Characteristics
    7. 6.7  LED Driver Electrical Characteristics
    8. 6.8  LED Test Electrical Characteristics
    9. 6.9  Logic Interface Characteristics
    10. 6.10 Recommended External Clock Source Conditions
    11. 6.11 Serial Bus Timing Parameters (SDA, SCL)
    12. 6.12 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Programming
      2. 7.3.2 LED Error Detection
      3. 7.3.3 Energy Efficiency
      4. 7.3.4 Temperature Compensation
      5. 7.3.5 Charge Pump Operational Description
        1. Overview
        2. Output Resistance
        3. Controlling The Charge Pump
        4. LED Forward Voltage Monitoring
        5. Gain Change Hysteresis
      6. 7.3.6 LED Driver Operational Description
        1. Overview
        2. Powering LEDs
        3. Controlling The High-Side LED Drivers
      7. 7.3.7 Automatic Power-Save Mode
      8. 7.3.8 PWM Power-Save Mode
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes Of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Control Interface
        1. Data Validity
        2. Start And Stop Conditions
        3. Transferring Data
      2. 7.5.2 I2C-Compatible Chip Address
        1. Control Register Write Cycle
        2. Control Register Read Cycle
        3. Auto-Increment Feature
    6. 7.6 Register Maps
      1. 7.6.1 Register Set
      2. 7.6.2 Control Register Details
      3. 7.6.3 Instruction Set
      4. 7.6.4 LED Driver Instructions
        1. Ramp
        2. Ramp Instruction Application Example
        3. Set_PWM
        4. Wait
      5. 7.6.5 LED Mapping Instructions
        1.  MUX_LD_START; MUX_LD_END
        2.  MUX_MAP_START
        3.  MUX_SEL
        4.  MUX_CLR
        5.  MUX_MAP_NEXT
        6.  MUX_LD_NEXT
        7.  MUX_MAP_PREV
        8.  MUX_LD_PREV
        9.  MUX_MAP_ADDR
        10. MUX_LD_ADDR
      6. 7.6.6 Branch Instructions
        1. BRANCH
        2. INT
        3. RST
        4. END
        5. TRIGGER
      7. 7.6.7 Arithmetic Instructions
        1. LD
        2. ADD
        3. SUB
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Using Two LP55231 in the Same Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      2. 8.2.2 Driving Haptic Feedback with LP55231
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 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 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

Application and Implementation


Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

Application Information

The LP55231 enables up to four parallel devices together, which can drive up to 12 RGB LEDs or 36 single LEDs. Figure 27 shows the connections for two LP55231 devices for six RGB LEDs. Note that D7, D8, and D9 outputs are used for the red LEDs. The SCL and SDA lines must each have a pullup resistor placed somewhere on the line (R3 and R4; the pullup resistors are normally located on the bus master.). In typical applications, values of 1.8 kΩ to 4.7 kΩ are used, depending on the bus capacitance, I/O voltage, and the desired communication speed. INT and TRIG are open-drain pins, which must have pullup resistors. Typical values for R1 and R2 are from 120 kΩ to 180 kΩ for two devices.

Typical Applications

Using Two LP55231 in the Same Application

LP55231 30198622.gif Figure 27. LP55231 Typical Application

Design Requirements

Input voltage range 2.7 V to 5.5 V
LED VF (maximum) 3.6 V
LED current 25.5 mA maximum
Input capacitor CIN1 = CIN2 = 1 μF
Output capacitor COUT1 = COUT2 = 1 μF
Charge pump fly capacitors C1 = C2 = C3 = C4 = 0.47 μF
Charge pump mode 1.5× or automatic

Detailed Design Procedure

The LP55231 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors are recommended. Tantalum and aluminium capacitors are not recommended because of their high ESR. For the flying capacitors (C1 and C2) multi-layer ceramic capacitors must always be used. These capacitors are small, inexpensive and have very low equivalent series resistance (ESR < 20 m typical). Ceramic capacitors with X7R or X5R temperature characteristic are preferred for use with the LP55231. These capacitors have tight capacitance tolerance (as good as ±10%) and hold their value over temperature (X7R: ±15% over −55°C to +125°C; X5R: ±15% over −55°C to +85°C). Capacitors with Y5V or Z5U temperature characteristic are generally not recommended for use with the LP55231. Capacitors with these temperature characteristics typically have wide capacitance tolerance (80%, −20%) and vary significantly over temperature (Y5V: 22%, −82% over −30°C to +85°C range; Z5U: 22%, −56% over 10°C to 85°C range). Under some conditions, a nominal 1-µF Y5V or Z5U capacitor could have a capacitance of only 0.1 µF. Such detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance requirements of the LP55231.

For proper operation it is necessary to have at least 0.24 μF of effective capacitance for each of the flying capacitors under all operating conditions. The output capacitor COUT directly affects the magnitude of the output ripple voltage. In general, the higher the value of COUT, the lower the output ripples magnitude. For proper operation it is recommended to have at least 0.50 μF of effective capacitance for CIN and COUT under all operating conditions. The voltage rating of all four capacitors should be 6.3 V; 10 V is recommended.

Table 9 lists suitable external components from some leading ceramic capacitor manufacturers. TI strongly recommends that the LP55231 circuit be thoroughly evaluated early in the design-in process with the mass-production capacitors of choice to help ensure that any variability in capacitance does not negatively impact circuit performance.

Table 9. Suitable External Components

1 µF for COUT and CIN
C1005X5R1A105K Ceramic X5R TDK 10 0402
LMK105BJ105KV-F Ceramic X5R Taiyo Yuden 10 0402
ECJ0EB1A105M Ceramic X5R Panasonic 10 0402
ECJUVBPA105M Ceramic X5R , array of two Panasonic 10 0504
0.47 µF for C1 and C2
C1005X5R1A474K Ceramic X5R TDK 10 0402
LMK105BJ474KV-F Ceramic X5R Taiyo Yuden 10 0402
ECJ0EB0J474K Ceramic X5R Panasonic 6.3 0402
LEDs User defined. Note that D7, D8, and D9 outputs are powered from VDD when specifying the LEDs.

Application Curves

LP55231 30198681.gif
1.5× to 1× 6 LEDs At 1 mA / 100% PWM
Figure 28. Line Transient and Charge Pump Automatic Gain Change
LP55231 30198682.gif
1.5× To 1× 6 LEDs At 1 mA / 100% PWM
Figure 29. Line Transient and Charge Pump Automatic Gain Change

Driving Haptic Feedback with LP55231

Figure 30 depicts an example schematic for LP55231 driving a vibra motor. A vibra motor can be used for haptic feedback with touch screens and also for normal vibra operation (call indication, and so forth). Battery-powered D8 and D9 outputs are used for controlling the H-Driver (Microchip TC442x series or equivalent), which drives the vibra motor. (The remaining outputs D1 to D7 can be used for LED driving.) With H-Driver the rotation direction of the vibra motor can be changed. For vibra operation user can load several programs to the LP55231 program memory in order to get interesting vibration effects, with changing frequency, ramps, etc.

LP55231 30198604.gif Figure 30. LP55231 Haptic Feedback Application

If the application processor has controls for a vibra motor they can be connected to H-Driver INA and INB as shown in Figure 30. In this case the vibra can be controlled directly with application processor and also with LP55231. If application processor control is not needed, then connect the 100-kΩ resistors to GND.

A simple waveform for H-driver control is shown in Figure 31. At first the motor rotates in CW direction for 30 ms, following a rotation of 30 ms in CCW direction. The sequence is started when the TRIG signal is pulled down (active low signal). the TRIG signal is received from the touch screen controller. After the sequence is executed, the LP55231 waits for another TRIG signal to start the sequence again. TRIG signal timing is not critical; it does not have to be pulled down for the whole sequence duration like in the example. For call indication, etc. purposes the program can be changed; for example, rotation times can be adjusted to get desired haptic reaction. Direct control of D8 and D9 output is also possible through the control registers, if programming is not desired.

LP55231 30198651.gif Figure 31. Control Waveform

Design Requirements

Input voltage range 2.7 V to 5.5 V
LED VF (maximum) 3.6 V
LED current 25.5 mA maximum
Input capacitor CIN1 = 1 μF
Output capacitor COUT = 1 μF
Charge pump fly capacitors C1 = C2 = 0.47 μF
Charge pump mode 1.5× or Automatic

Detailed Design Procedure

External component selection follows the earlier example (see Detailed Design Procedure above). H-Bridge must be selected to have high enough current capability for the vibra motor and control interface suitable for LP55231 LED outputs.

Application Curves

See Application Curves above.