SNVSA29 May   2015 LM36922

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 I2C Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Enabling the LM36922
        1. 7.3.1.1 Current Sink Enable
      2. 7.3.2 LM36922 Start-Up
      3. 7.3.3 Brightness Mapping
        1. 7.3.3.1 Linear Mapping
        2. 7.3.3.2 Exponential Mapping
      4. 7.3.4 PWM Input
        1. 7.3.4.1 PWM Sample Frequency
          1. 7.3.4.1.1 PWM Resolution and Input Frequency Range
          2. 7.3.4.1.2 PWM Sample Rate and Efficiency
            1. 7.3.4.1.2.1 PWM Sample Rate Example
        2. 7.3.4.2 PWM Hysteresis
        3. 7.3.4.3 PWM Step Response
        4. 7.3.4.4 PWM Timeout
      5. 7.3.5 LED Current Ramping
      6. 7.3.6 Regulated Headroom Voltage
    4. 7.4 Device Functional Modes
      1. 7.4.1 Brightness Control Modes
        1. 7.4.1.1 I2C Only (Brightness Mode 00)
        2. 7.4.1.2 PWM Only (Brightness Mode 01)
        3. 7.4.1.3 I2C + PWM Brightness Control (Multiply Then Ramp) Brightness Mode 10
        4. 7.4.1.4 I2C + PWM Brightness Control (Ramp Then Multiply) Brightness Mode 11
      2. 7.4.2 Boost Switching Frequency
        1. 7.4.2.1 Minimum Inductor Select
      3. 7.4.3 Auto Switching Frequency
      4. 7.4.4 Backlight Adjust Input (BL_ADJ)
        1. 7.4.4.1 Back-Light Adjust Input Polarity
      5. 7.4.5 Fault Protection/Detection
        1. 7.4.5.1 Overvoltage Protection (OVP)
          1. 7.4.5.1.1 Case 1 OVP Fault Only (OVP Threshold Hit and All Enabled Current Sink Inputs > 40 mV)
          2. 7.4.5.1.2 Case 2a OVP Fault and Open LED String Fault (OVP Threshold Occurrence and Any Enabled Current Sink Input ≤ 40 mV)
          3. 7.4.5.1.3 Case 2b OVP Fault and Open LED String Fault (OVP Threshold Duration and Any Enabled Current Sink Input ≤ 40 mV)
          4. 7.4.5.1.4 OVP/LED Open Fault Shutdown
          5. 7.4.5.1.5 Testing for LED String Open
        2. 7.4.5.2 LED String Short Fault
        3. 7.4.5.3 Overcurrent Protection (OCP)
          1. 7.4.5.3.1 OCP Fault
          2. 7.4.5.3.2 OCP Shutdown
        4. 7.4.5.4 Device Overtemperature (TSD)
          1. 7.4.5.4.1 Overtemperature Shutdown
    5. 7.5 Programming
      1. 7.5.1 I2C Interface
        1. 7.5.1.1 Start and Stop Conditions
        2. 7.5.1.2 I2C Address
        3. 7.5.1.3 Transferring Data
        4. 7.5.1.4 Register Programming
    6. 7.6 Register Maps
  8. 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 Component Selection
          1. 8.2.2.1.1 Inductor
          2. 8.2.2.1.2 Output Capacitor
          3. 8.2.2.1.3 Input Capacitor
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Input Supply Bypassing
  10. 10Layout
    1. 10.1 Layout Guidelines
      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 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

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
IN Input voltage –0.3 6 V
OUT Output overvoltage sense input –0.3 30 V
SW Inductor connection –0.3 30 V
LED1, LED2 LED string cathode connection –0.3 30 V
HWEN, PWM, SDA, SCL, BL_ADJ Logic I/Os –0.3 6 V
Maximum junction temperature, TJ_MAX 150 °C
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, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute–maximum–rated conditions for extended periods may affect device reliability.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±500
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Pins listed as ±2000 V may actually have higher performance.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Pins listed as ±500 V may actually have higher performance.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
IN Input voltage 2.5 5.5 V
OUT Overvoltage sense input 0 29.5 V
SW Inductor connection 0 29.5 V
LED1, LED2 LED string cathode connection 0 29.5 V
HWEN, PWM, SDA, SCL, BL_ADJ Logic I/Os 0 5.5 V

6.4 Thermal Information

THERMAL METRIC(1) YFQ (DSBGA) UNIT
12 PINS
RθJA Junction-to-ambient thermal resistance 88.9
 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 0.7
RθJB Junction-to-board thermal resistance 43.9
ΨθJT Junction-to-top characterization parameter 2.9
ΨθJB Junction-to-board characterization parameter 43.7
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

Limits apply over the full operating ambient temperature range (−40°C ≤ TA ≤ 85°C) and VIN = 3.6 V, typical values are at TA = 25°C (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
BOOST
IMATCH(1) LED current matching ILED1 to ILED2 50 µA ≤ ILED ≤ 25 mA, 2.7 V ≤ VIN ≤ 5 V (linear or exponential mode) –1% 0.1% 1%
Accuracy Absolute Accuracy (ILED1, ILED2) 50 µA ≤ ILED ≤ 25 mA, 2.7 V ≤ VIN ≤ 5 V (linear or exponential mode) –3% 0.1% 3%
ILED_MIN Minimum LED current (per string) PWM or I2C current control (linear or exponential mode) 50 µA
ILED_MAX Maximum LED current (per string) 25 mA
RDNL IDAC ratio-metric DNL exponential mode only 1/3
(0.3%) 		LSB
VHR Regulated current sink headroom voltage ILED = 25 mA 210 mV
ILED = 5 mA 100
VHR_MIN Current sink minimum headroom voltage ILED = 95% of nominal, ILED = 5 mA 35 50 mV
Efficiency Typical efficiency VIN = 3.7 V, ILED = 5 mA/string, typical application circuit (2x8 LEDs), POUT/PIN) 86%
RNMOS NMOS switch on resistance ISW = 250 mA 0.25 Ω
ICL NMOS switch current limit 2.7 V ≤ VIN ≤ 5 V OCP = 00 575 750 875 mA
OCP = 01 860 1000 1110
OCP = 10 1100 1250 1400
OCP = 11 1350 1500 1650
VOVP Output overvoltage protection ON threshold, 2.7 V ≤ VIN ≤ 5 V OVP = 00 16 17 17.5 V
OVP = 01 20 21 21.5
OVP = 10 24 25 25.5
OVP = 11 28 29 29.5
OVP Hysteresis 0.5 V
ƒSW Switching frequency 2.7 V ≤ VIN ≤ 5 V, boost frequency
shift = 0		 Boost frequency select = 0 475 500 525 kHz
Boost frequency select = 1 950 1000 1050
DMAX Maximum boost duty cycle 92% 94%
ISHDN Shutdown current Chip enable bit = 0, SDA = SCL = IN or GND, 2.7 V ≤ VIN ≤ 5 V 1.2 5 µA
TSD Thermal shutdown 135 °C
Hysteresis 15
PWM INPUT
Min ƒPWM 50 Hz
Max ƒPWM Sample rate = 24 MHz 50 kHz
tMIN_ON Minimum pulse ON time Sample rate = 24 MHz 183.3 ns
Sample rate = 4 MHz 1100
Sample rate = 800 kHz 5500
tMIN_OFF Minimum pulse OFF time Sample rate = 24 MHz 183.3 ns
Sample rate = 4 MHz 1100
Sample rate = 800 kHz 5500
tSTART-UP Turn-on delay from shutdown to backlight on PWM input active, PWM = logic high,HWEN input from low to high, ƒPWM = 10 kHz (50% duty cycle) 3.5 5 ms
PWMRES PWM input resolution 1.6 kHz ≤ ƒPWM ≤ 12 kHz, PWM hysteresis = 00, PWM sample rate = 11 11 bits
VIH Input logic high HWEN, BL_ADJ, SCL, SDA, PWM inputs 1.25 VIN V
VIL Input logic low HWEN, BL_ADJ, SCL, SDA, PWM inputs 0 0.4
tGLITCH PWM input glitch rejection PWM pulse filter = 00 0 15 ns
PWM pulse filter = 01 60 100 140
PWM pulse filter = 10 90 150 210
PWM pulse filter = 11 120 200 280
tPWM_STBY PWM shutdown period Sample rate = 24 MHz 0.54 0.6 0.66 ms
Sample rate = 4 MHz 2.7 3 3.3
Sample rate = 800 kHz 22.5 25 27.5
(1) LED Current Matching between strings is given as the worst case matching between any two strings. Matching is calculated as ((ILEDX – ILEDY)/(ILEDX + ILEDY) × 100.

6.6 I2C Timing Requirements

MIN TYP MAX UNIT
t1 SCL clock period 2.5 µs
t2 Data in setup time to SCL high 100 ns
t3 Data out stable after SCL low 0 ns
t4 SDA low Setup Time to SCL low (start) 100 ns
t5 SDA high hold time after SCL high (stop) 100 ns
LM36922 I2Ctime_diag.gifFigure 1. I2C Timing

6.7 Typical Characteristics

LM36922 C002_SNVSA30.png
Figure 2. OVP Hysteresis
LM36922 C004_SNVSA30.png
Figure 4. 21-V OVP Threshold
LM36922 C006_SNVSA30.png
Figure 6. 29-V OVP Threshold
LM36922 C008_SNVSA30.png
HWEN = GND
Figure 8. Shutdown Current
LM36922 C011_SNVSA30.png
ILED = 25 mA
Figure 10. VHR MIN
LM36922 C013_SNVSA30.png
Open Loop
Figure 12. 1000-mA OCP Current
LM36922 C015_SNVSA30.png
Open Loop
Figure 14. 1500-mA OCP Current
LM36922 C003_SNVSA30.png
Figure 3. 17-V OVP Threshold
LM36922 C005_SNVSA30.png
Figure 5. 25-V OVP Threshold
LM36922 C007_SNVSA30.png
Figure 7. RDSON
LM36922 C010_SNVSA30.png
fSW= 1 Mhz No Load
Figure 9. IQ Current (Switching)
LM36922 C012_SNVSA30.png
Open Loop
Figure 11. 750-mA OCP Current
LM36922 C014_SNVSA30.png
Open Loop
Figure 13. 1250-mA OCP Current