FIND Vol.23 No.5 2005 27 MB39C011 A -INE1 7 VB VB VB step-down VB << CH1 >> (1.8u) (0.8u) Error Amp1 (1.8u) (0.8u) PWM Comp1 + + + A Vo1 (3.3V) OUT1-1 Drive1-1 Pch 2 6 Drive1-2 Nch 3 10 << CH2 >> AST - 1.0V FB1 Vcc OUT1-2 step-down -INE2 Error Amp2 + + VIN (6V to 17V) + - 1.0V FB2 B PWM Comp2 Vo2 (2.0V) OUT2-1 Drive2-1 Pch 15 Drive2-2 Nch 14 AST B OUT2-2 11 VB SCP Comp1 (1.7V) + CSCP2 (0.7V) (1.7V) 1.9V + VB 9 4 (0.7V) VB SCP Comp2 2.0V + VH (Vcc-5V) VH 1.9V CSCP1 8 Bias Voltage + - 16 SR Latch Reset 2.0V UVLO VB (5V) VCC OSC bias 1 ErrorAmp Ref. (1.0V) Bias Voltage VR1 Power ON/OFF CTL CT 5 CTL H:ON (Power ON) L:OFF(Standby mode) VTH=1.4V 12 RT 28 13 GND FIND Vol.23 No.5 2005 MB39C011 A -INE1 7 VB VB VB step-down VB Vcco << CH1 >> Error Amp1 (1.8u) (0.8u) PWM Comp1 + + + 1.0V FB1 Vo1 (3.3V) OUT1-1 Drive1-1 - A 21 Pch 1 Drive1-2 Nch 2 AST (1.8u) (0.8u) 5 OUT1-2 step-down -INE2 12 Error Amp2 + + VIN (6V to 17V) + PWM Comp2 - 1.0V FB2 B << CH2 >> Vo2 (2.0V) OUT2-1 Drive2-1 Pch 18 Drive2-2 Nch 17 AST B OUT2-2 13 PGND 15 VB SCP Comp1 (1.7V) + CSCP2 (0.7V) (1.7V) 1.9V + VB 11 3 (0.7V) VB SCP Comp2 2.0V + VH (Vcc-5V) VH 1.9V CSCP1 8 Bias Voltage + - 20 SR Latch Reset 2.0V UVLO VB (5V) VCC OSC bias 22 ErrorAmp Ref. (1.0V) Bias Voltage VR1 Power ON/OFF CTL CT 4 Vol.23 No.5 2005 CTL H:ON (Power ON) L:OFF(Standby mode) VTH=1.4V 14 RT FIND 16 GND 29 MB39C011 30 FIND Vol.23 No.5 2005