Power Electronics Group

Power Electronics

◈ Power management integrated circuits (PMICs)

◇ Introduction

- Recently, most of electronic systems require that the power consumption is reduced and the reliability is enhanced.
Power management integrated circuits (PMICs) are a system block in a system-on-a-chip (SoC) device for managing power
consumption. PMICs are often used in liquid crystal display (LCD) applications using light-emitting diode (LED) backlight or
battery operated devices such as mobile phones and portable media players. PMICs include a DC-DC converter, an AC-DC
rectifier, a DC-AC invertor, and an AC-AC cycloconvertor. In mobile devices, the potable battery is used and DC-DC converters
are applied to generate required DC voltages. In many consumer electronics, a AC-DC rectifier is used to generate DC voltage
and the generated DC voltage is converted to required DC voltages by DC-DC converters. Many PMICs are often fabricated by
bipolar-CMOS-DMOS (BCD) process to sustain high voltage.

- Power management group in IELAB researches LED backlight driving system for notebooks and LCD TVs, PMIC for mobile
devices, battery management integrated circuit (BMIC) for mobile devices, AC-DC rectifier for LED lighting applications and
BCD process for PMIC.

    ◇ Research area
      · LED backlight driving system
          - LED backlight driving system for laptops
          - LED backlight driving system for LCD TVs
      · PMIC and BMIC for mobile devices
          - DC-DC converter
          - Low drop-out (LDO) regulator
          - Battery charger
          - Battery protection
      · AC-DC rectifier for LED lighting applications
          - AC-DC rectifier with LED control circuit
      · BCD device and process for PMIC
          - Lateral double diffused MOSFET (LDMOSFET) design
          - Modeling LDMOSFET
          - BCD process integration
          - Reliability


LCD television (TV) with LED backlight	Power management IC for mobile device	LED lighting for smart grid

    ◇ Research results
      · LED backlight driving system
          - LED backlight driving system for laptops

    ◇ Specifications
          - Process : 0.35-μm 5 V-60 V BCD process
          - V_in : 6 V ~ 27 V
          - V_out (max) : 60 V
          - I_LED (max) : 30 mA
          - Number of channels : 6
          - Rising time of I_LED : 86 ns
          - Resolution : 8-bit


Block diagram	Prototype


Measured results	Chip microphotograph

    ◇ Research results
      · LED backlight driving system
          - LED backlight driving system for LCD TVs

    ◇ Specifications
          - Process : 0.35-μm 5 V-60 V BCD process
          - V_in : 10 V ~ 36 V
          - V_out (max) : 60 V
          - I_LED (max) : 30 mA
          - Number of channels : 48
          - Rising time of I_LED : 4.8 ns
          - Resolution : 12-bit
          - Current uniformity < 2 %


Block diagram	Prototype


Measured results	Layout diagrams

    ◇ Research results
      · PMIC and BMIC for mobile devices
          - Single inductor multi-output (SIMO) DC-DC converter

    ◇ Specifications
          - V_in : 2.7 V ~ 4.2 V (Li-ion Battery)
          - Number of output : 5
          - Efficiency (max) : 88 %


Block diagram	Timing diagram	Simulated results

    ◇ Research results
      · PMIC and BMIC for mobile devices
          - Battery management system

    ◇ Specifications
          - Battery charger
          - Over voltage protection
          - Over current protection
          - Over temperature protection


Block diagram	Timing diagram


Layout diagram	Simulated results

    ◇ Research results
      · LED lighting
          - AC-DC rectifier with LED control circuit

    ◇ Specifications
          - V_in : 220 V / 110 V (AC 60 Hz)
          - P_output : 4 W ~ 20 W
          - Power efficiency (max) : 92 %
          - Power factor (min) : 97 %
          - Power line communication (PLC)


Block diagram	Board layout

Simulated results

    ◇ Research results
      · Device and process for PMIC
          - BCD process integration with 85 V LDMOSFET

    ◇ Specifications (85 V high voltage LDMOSFET)
          - Breakdown voltage : 120 V
          - R_on,sp of LDMOSFET : 1.5 mΩ·cm²
          - Second breakdown voltage : 92 V (@ V_gs = 12 V)


Cross section of BCD process	Measured results of 85 V LSD LDMOSFET

    ◇ Research results
      · Device and process for PMIC
          - 60 V LDMOSFET modeling

    ◇ Specifications
          - Peak accuracy < 10 %
          - RMS accuracy < 5 %


DC model of 60 V LDMOSFET	AC model of 60 V LDMOSFET


Measured results of DC characteristics	Measured results of AC characteristics

    ◇ Research results
      · Device and process for PMIC
          - Reliability (SOA)

    ◇ Specifications
          - V_out (max) : 100 V, Iout (max) : 10 A
          - SOA evaluation and UIS / CIS test


SOA test board	Measured results for SOA test	Measured results for UIS test

          - Reliability (ESD)

    ◇ Specifications
          - (LV / HV) input/output clamp and power clamp
          - HBM 3000 V & MM 300 V


Block diagram for ESD protection system	Measured results for HBM test