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  • TPS61181A White-LED Driver For Notebook Display

    • SLVSAN6B February   2011  – September 2016 TPS61181A

      PRODUCTION DATA.  

  • CONTENTS
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  • TPS61181A White-LED Driver For Notebook Display
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Supply Voltage
      2. 8.3.2 Boost Regulator
      3. 8.3.3 Enable and Start-Up
      4. 8.3.4 Overcurrent, Overvoltage, and Short-Circuit Protection
      5. 8.3.5 IFB Pin Unused
    4. 8.4 Device Functional Modes
      1. 8.4.1 Current Program and PWM Dimming
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inductor Selection
        2. 9.2.2.2 Output Capacitor Selection
        3. 9.2.2.3 Audible Noise Reduction
        4. 9.2.2.4 Isolation MOSFET Selection
      3. 9.2.3 Application Curves
    3. 9.3 Additional Application Circuits
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device And Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
  14. IMPORTANT NOTICE
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DATA SHEET

TPS61181A White-LED Driver For Notebook Display

1 Features

  • 4.5-V to 24-V Input Voltage
  • 38-V Maximum Output Voltage
  • Integrated 1.5-A/40-V MOSFET
  • 1-MHz Switching Frequency
  • Adaptive Boost Output to WLED Voltages
  • Small External Components
  • Integrated Loop Compensation
  • Six Current Sinks of 30 mA
  • Up to 10 WLED in Series
  • 1% Typical Current Matching and Accuracy
  • Up to 1000:1 PWM Brightness Dimming
  • Minimized Output Ripple Under PWM Dimming
  • Driver for Input/Output Isolation PFET
  • True Shutdown
  • Overvoltage Protection
  • WLED Open and Short Protection
  • Built-in Soft Start

2 Applications

  • Notebook LCD Display Backlight
  • UMPC LCD Display Backlight
  • Backlight for Media Form Factor LCD Display

3 Description

The TPS61181A device provides highly integrated solutions for media-size LCD backlighting. The six current sink regulators provide high-precision current regulation and matching. In total, the device can support up to 60 WLEDs.

The devices support pulse width modulation (PWM) brightness dimming. During dimming, the WLED current is turned on/off at the duty cycle and frequency, determined by the PWM signal input to the DCRTL pin. The TPS61181A device is designed to minimize the output AC ripple across a wide dimming duty cycle and frequency range and also reduces the audible noise from the output ceramic capacitors.

The TPS61181A device provides a driver output for an external PFET connected between the input and inductor. During short circuit or overcurrent conditions, the device turns off the external PFET and disconnects the battery from the WLEDs. The PFET is also turned off during device shutdown (thereby giving true shutdown) to prevent any leakage current from the battery. The device integrates overvoltage protection, soft-start and thermal shutdown and has a built-in linear regulator for the device supply.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
TPS61181A WQFN (16) 3.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

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TPS61181A Typical Application

TPS61181A app_sch_lvsan6.gif

4 Revision History

Changes from A Revision (March 2011) to B Revision

  • Added Device Information and Pin Configuration and Functions sections, Device Comparison and ESD Ratings tables, Feature Description, Device Functional Modes, Application and Implementation, Power Supply Recommendations, Layout, Device and Documentation Support, and Mechanical, Packaging, and Orderable Information sections; minor changes to page 1 to delete redundant contentGo
  • Deleted the Ordering Information table, see POA at the end of the data sheet Go

Changes from * Revision (February) to A Revision

  • Deleted Voltage Range spec for "all other pins" in the Absolute Maximum Ratings table.Go
  • Added FPWM spec. for PWM dimming frequency at DPWM ≥ 1% and DPWM ≥ 5%Go

5 Device Comparison Table

TPS61181A TPS61180
Input voltage range 5 V to 24 V 5 V to 24 V
Number of LED channels 6 6
LED current/channel 30 25
I2C/SPI support No No

6 Pin Configuration and Functions

RTE Package
16-Pin WQFN
Top View
TPS61181A po_lvsan6.gif

Pin Functions

PIN I/O DESCRIPTION
NO. NAME
1 PGND I Power ground of the device. Internally, it connects to the source of the PWM switch.
2 SW I This pin connects to the drain of the internal PWM switch, external Schottky diode and inductor.
3 VBAT I This pin is connected to the battery supply. It provides the pullup voltage for the Fault pin and battery voltage signal. This is also the input to the internal LDO.
4 VO O This pin monitors the output of the boost regulator. Connect this pin to the anode of the WLED strings.
5 ISET I The resistor on this pin programs the WLED output current.
6 Cin I Supply voltage of the device. It is the output of the internal LDO. Connect 0.1-μF bypass capacitor to this pin.
7, 8, 9
12, 13, 14		 IFB1-IFB3
IFB4-IFB6		 I Current sink regulation inputs. They are connected to the cathode of WLEDs. The PWM loop regulates the lowest VIFB to 400  mV. Each channel is limited to 30-mA current.
10 GND I Signal ground of the device.
11 DCTRL I Dimming control logic input. The dimming frequency range is 100 Hz to 1 kHz.
15 EN I The enable pin to the device. A logic high signal turns on the internal LDO and enables the device. Therefore, do not connect the EN pin to the Cin pin.
16 Fault I Gate driver output for an external PFET used for fault protection. It can also be used as signal output for system fault report.

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted) (1)
MIN MAX UNIT
Voltage range(2) VBAT and Fault –0.3 24 V
CIN and ISET –0.3 3.6
SW and VO –0.3 40
IFB1 to IFB6, EN and DCTRL –0.3 20
Continuous power dissipation See Thermal Information
Operating junction temperature range –40 150 °C
Storage temperature range –65 150
(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) All voltage values are with respect to network ground terminal.

7.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±3000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±200
Machine mode (MM) 1000
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

MIN NOM MAX UNIT
VBAT Battery input voltage range 4.5 24 V
VO Output voltage range Vin 38 V
L Inductor 4.7 10 μH
CO Output capacitor 2.2 10 μF
FPWM PWM dimming frequency at DPWM ≥ 1% 0.1 1 kHz
PWM dimming frequency at DPWM ≥ 5% 1 5
TA Operating ambient temperature –40 85 °C
TJ Operating junction temperature –40 125 °C

7.4 Thermal Information

THERMAL METRIC(1) TPS61181A UNIT
RTE (WQFN)
16 PINS
RθJA Junction-to-ambient thermal resistance 43.1 °C/W
RθJCtop Junction-to-case (top) thermal resistance 38.3 °C/W
RθJB Junction-to-board thermal resistance 14.6 °C/W
RψJT Junction-to-top characterization parameter 0.4 °C/W
RψJB Junction-to-board characterization parameter 14.4 °C/W
RθJCbot Junction-to-case (bottom) thermal resistance 3.6 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

7.5 Electrical Characteristics

VBAT = 10.8 V, 0.1 μF at Cin, EN = logic high, IFB current = 20 mA, IFB voltage = 500 mV, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY CURRENT
VBAT Battery input voltage range 4.5 24 V
Vcin Cin pin output voltage 2.7 3.15 3.6 V
Iq_bat Operating quiescent current into VBAT Device enable, switching no load,
VIN = 24 V		 3 mA
IQ_sw Operating quiescent current into VO VO = 35 V 60 μA
ISD Shutdown current EN=GND 2 18 μA
Vbat_UVLO VBAT undervoltage lockout threshold VBAT rising 4.45 V
VBAT falling 3.9
Vbat_hys VBAT undervoltage lockout hysteresis VBAT rising – VBAT falling 220 mV
EN AND DCTRL
VH EN pin logic high voltage 2 V
VL EN pin logic low voltage 0.8 V
VH DCTRL pin logic high voltage 2 V
VL DCTRL pin logic low voltage 0.8 V
RPD Pulldown resistor on both pins VEN, DCTRL = 2 V 400 800 1600 kΩ
CURRENT REGULATION
VISET ISET pin voltage 1.204 1.229 1.253 V
KISET Current multiple Iout/ISET ISET current = 20 μA 970 1000 1030
IFB Current accuracy ISET current = 20 µA 19.4 20 20.6 mA
Km (Imax – Imin) / IAVG ISET current = 20 μA 1% 2.5%
Ileak IFB pin leakage current IFB voltage = 20 V on all pins 3 μA
IIFB_MAX Current sink max output current IFB = 500 mV 30 mA
BOOST OUTPUT REGULATION
VIFB_L VO dial up threshold ISET current = 20 μA 400 mV
VIFB_H VO dial down threshold ISET current = 20 μA 700 mV
Vreg_L Min VO regulation voltage 16 V
Vo_step VO stepping voltage 100 150 mV
POWER SWITCH
RPWM_SW PWM FET on-resistance 0.2 0.45 Ω
Rstart Start up charging resistance VO = 0 V 100 300 Ω
Vstart_r Isolation FET start-up threshold VIN – VO, VO ramp up 1.2 2 V
ILN_NFET PWM FET leakage current VSW = 35 V 1 μA
OSCILLATOR
fS Oscillator frequency 0.9 1 1.2 MHz
Dmax Maximum duty cycle IFB = 0 V 94%
Dmin Minimum duty cycle 7%
OS, SC, OVP AND SS
ILIM N-channel MOSFET current limit D = Dmax 1.5 3 A
Vovp VO overvoltage threshold Measured on the VO pin 38 39 40 V
Vovp_IFB IFB overvoltage threshold Measured on the IFBx pin 15 17 20 V
Vsc Short-circuit detection threshold VIN – VO, VO ramp down 1.7 2.5 V
Vsc_dly Short-circuit detection delay during start up 32 ms
FAULT OUTPUT
Vfault_high Fault high voltage Measured as VBAT – VFault 0.1 V
Vfault_low Fault low voltage Measured as VBAT – VFault, sink 0.1 mA
VIN = 15 V		 6 8 10 V
THERMAL SHUTDOWN
Tshutdown Thermal shutdown threshold 160 °C
Thysteresis Thermal shutdown threshold hysteresis 15 °C

7.6 Typical Characteristics

Table 1. Table of Graphs

Description (Reference to application circuit in Figure 16) Figure
Dimming Linearity Vbat = 10.8 V; VO=28.6 V, 9 LEDs; Iset= 20 μA; PWM Freq = 1 kHz Figure 1
Dimming Linearity Vbat = 10.8 V; VO=28.6 V, 9 LEDs; Iset= 20 μA; PWM Freq = 200 Hz Figure 2
Output Ripple VO = 28.6 V; Iset= 20 μA; PWM Freq = 200 Hz; Duty = 50% Figure 3
Switching Waveform Vbat = 10.8 V; Iset= 20μA Figure 4
Output Ripple at PWM Dimming Vbat = 10.8 V; Iset = 20 μA; PWM Freq = 200 Hz; Duty = 50%; CO = 4.7 μF Figure 5
Short Circuit Protection Vbat = 10.8 V; Iset = 20 μA Figure 6
Open WLED Protection Vbat = 10.8 V; Iset = 20 μA Figure 7
Startup Waveform Vbat = 10.8 V; Iset = 20 μA Figure 8
DC Load Efficiency Vbat = 5 V, 10.8 V, 19 V; VO = 28.6 V, 9 LEDs; L = 10 µH Figure 10
DC Load Efficiency Vbat = 5V, 10.8 V, 19 V; VO = 31.7 V, 10 LEDs; L =10 µH Figure 11
PWM Dimming Efficiency Vbat = 5V, 10.8 V and 19 V; VO = 25.5 V, 8 LEDs; PWM Freq = 1 kHz Figure 12
PWM Dimming Efficiency Vbat = 5V, 10.8 V and 19 V; VO = 28.6 V, 9 LEDs; PWM Freq = 1 kHz Figure 13
PWM Dimming Efficiency Vbat = 5V, 10.8 V and 19 V; VO = 31.7 V, 10 LEDs; PWM Freq = 1 kHz Figure 14
PWM Dimming Efficiency Vbat = 5V, 10.8 V and 19 V; VO=34.8 V, 11 LEDs; PWM Freq = 1 kHz Figure 15
TPS61181A dim_lin1_lvsan6.gif
1 kHz
Figure 1. PWM Dimming Linearity
TPS61181A out_rip_lvsan6.gif
COUT = 4.7 μF
Figure 3. PWM Dimming Output Ripple vs Input Voltage
TPS61181A outb_rip_dim_lvs801.gif
COUT = 4.7 μF
Figure 5. Output Ripple at PWM Dimming
TPS61181A openb_wield_lvs801.gif
Figure 7. Open WLED Protection
TPS61181A dim_lin2_lvsan6.gif
200 Hz
Figure 2. PWM Dimming Linearity
TPS61181A swtb_wf_lvs801.gif
Figure 4. Switching Waveform
TPS61181A outb_shrt_lvs801.gif
Figure 6. Output Short Protection
TPS61181A startup_lvs801.gif
Figure 8. Start-up Waveform

 
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