FUJITSU SEMICONDUCTOR DATA SHEET DS04-27217-5E ASSP For Power Supply Applications Pentium® DC/DC Converter IC MB3828 ■ DESCRIPTION The FUJITSU MB3828 is a pulse width modulation (PWM) DC/DC converter IC chip that provides a selection of 1.3 V to 3.5 V output voltages for Pentium®* CPU’s, using a 5-bit input signal information. The MB3828 utilizes synchronous rectification for high efficiency and features a soft-start/discharge control function for ease in designing power supplies in multi-supply systems, making it ideal for Pentium® power supply systems. * : Pentium is the registered trademark of Intel Corporation. ■ FEATURES • • • • • • • • Highly efficient for using synchronous rectification scheme On-chip soft-start/discharge control circuit High precision output voltage: ±1.2% 5-bit, 32-step DAC: 3.5 V to 2.1 V in 100 mV steps 2.05 V to 1.3 V in 50 mV steps Frequency range: 100 kHz to 500 kHz using variable resistance (on-chip frequency setting capacitance) Standby current: 0 µA TYP On-chip PWRGOOD circuit for output voltage state detection Timer-latch short-circuit protection circuit, and overvoltage protection circuit for output protection ■ PACKAGE 24-pin Plastic SSOP (FPT-24P-M03) MB3828 ■ PIN ASSIGNMENT (Top view) RT : 1 24 : VREF RS : 2 23 : VCC SGND : 3 22 : CSCP CS : 4 21 : PWRGOOD –IN : 5 20 : VSENSE FB : 6 19 : CTL ENB : 7 18 : VD4 OUT1 : 8 17 : VD3 VS : 9 16 : VD2 CB : 10 15 : VD1 OUT2 : 11 14 : VD0 PGND : 12 13 : VB (FPT-24P-M03) 2 MB3828 ■ PIN DESCRIPTION Pin no. Symbol I/O Descriptions 1 RT — Triangular wave frequency setting resistor connection pin 2 RS — Discharging resistor connection pin for soft start capacitor 3 SGND — Ground pin 4 CS — Soft start capacitor connection pin (Also used for discharge control) 5 –IN I Error amplifier inverted input pin 6 FB O Error amplifier output pin 7 ENB I Discharge control function enable/disable switch control pin 8 OUT1 O Totem-pole output pin (External main-side FET gate drive) 9 VS — External main-side FET source-side connection 10 CB — Output bootstrap pin Insert a capacitor between the CB and VS pins, to bootstrap the IC internal output transistor. 11 OUT2 O Totem-pole output pin (External synchronous rectifier-side FET gate drive) 12 PGND — Ground pin 13 VB — Output circuit power supply pin 14 VD0 I 5-bit digital input pin used to set DC/DC converter output voltage 15 VD1 I 5-bit digital input pin used to set DC/DC converter output voltage 16 VD2 I 5-bit digital input pin used to set DC/DC converter output voltage 17 VD3 I 5-bit digital input pin used to set DC/DC converter output voltage 18 VD4 I 5-bit digital input pin used to set DC/DC converter output voltage 19 CTL I Power supply control pin The CTL pin is set to “L” level to place the IC in standby mode. 20 VSENSE I PWRGOOD circuit input pin 21 PWRGOOD O PWRGOOD output pin (open-drain output) Outputs a “H” level signal when the output voltage is within the range from VTLOW to VTHIGH. 22 CSCP — Timer-latch short-circuit protection capacitor connection pin 23 VCC — Power supply pin for reference power and control circuit 24 VREF O Reference voltage output pin 3 MB3828 ■ BLOCK DIAGRAM VSENSE PWRGOOD 21 20 POWERGOOD PWRGD CS –IN FB – + + 5 (±10%) 13 Overvoltage protection (17.5%) OVP PWM Comp.1 + + DTC – Error Amp. 10 Drive 1 6 PWM Comp.2 VB RS VB CB OUT1 8 9 VS + 2 – CS Drive 2 4 OUT2 11 12 PGND + VD0 14 VD1 15 VD2 16 VCS D/A CS Comp. bias 19 CTL 7 ENB (5-bit) SCP Comp. VD3 17 bias + VD4 18 OSC SCP VSCP CT (40 pF) 1 RT 4 CTL LOGIC – – UVLO Ref Power ON/OFF CTL (3.5 V) 22 CSCP 24 3 VREF SGND VCC 23 MB3828 ■ OUTPUT VOLTAGE SETTING CODE VD4 VD3 VD2 VD1 VD0 VD (DC/DC converter output voltage) (V) 1 0 0 0 0 3.500 1 0 0 0 1 3.400 1 0 0 1 0 3.300 1 0 0 1 1 3.200 1 0 1 0 0 3.100 1 0 1 0 1 3.000 1 0 1 1 0 2.900 1 0 1 1 1 2.800 1 1 0 0 0 2.700 1 1 0 0 1 2.600 1 1 0 1 0 2.500 1 1 0 1 1 2.400 1 1 1 0 0 2.300 1 1 1 0 1 2.200 1 1 1 1 0 2.100 1 1 1 1 1 0 (output OFF) 0 0 0 0 0 2.050 0 0 0 0 1 2.000 0 0 0 1 0 1.950 0 0 0 1 1 1.900 0 0 1 0 0 1.850 0 0 1 0 1 1.800 0 0 1 1 0 1.750 0 0 1 1 1 1.700 0 1 0 0 0 1.650 0 1 0 0 1 1.600 0 1 0 1 0 1.550 0 1 0 1 1 1.500 0 1 1 0 0 1.450 0 1 1 0 1 1.400 0 1 1 1 0 1.350 0 1 1 1 1 1.300 5 MB3828 ■ ABSOLUTE MAXIMUM RATINGS Parameter Symbol Condition Value Unit Power supply voltage VCC — 20 V Bias voltage VB — 20 V Boot voltage VCB — 32 V Control input voltage VCTL — 20 V PWRGOOD output voltage VPWRGD — 17 V Output current IO — 50 mA Peak output current IO Duty ≤ 5% (t = 1/fOSC × Duty) 500 mA Allowable dissipation PD Ta ≤ +25°C 740* mW Storage temperature Tstg –55 to +125 °C — * : When mounted on a 10 cm-square dual-sided epoxy base board WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. 6 MB3828 ■ RECOMMENDED OPERATING CONDITIONS Parameter Symbol Condition Value Min. Typ. Max. Unit Power supply voltage VCC — 4.6 5 18 V Bias voltage VB — — 5 18 V Boot voltage VCB — — — 30 V Reference voltage output current IOR — –1 — 0 mA VIN –IN pin 0 — VCC – 0.9 V VIN CTL, ENB, VD4 to VD0 pins 0 — 18 V VIN VSENSE 0 — VCC V IO OUT pin –30 — 30 mA IPG PWRGOOD pin — — 1 mA Peak output current IO Duty ≤ 5% (t = 1/fOSC × Duty) –300 — 300 mA Oscillator frequency fOSC — 100 200 500 kHz Timing resistance RT — 51 130 270 kΩ Boot capacitance CB — — 0.1 1.0 µF Reference voltage output capacitance CREF — — 0.1 1.0 µF Soft start capacitance CS — — 4700 10000 pF Discharge control resistance RS — — 100 470 kΩ Short detection capacitance CSCP — — 2200 10000 pF Operating temperature Ta — –30 +25 +85 °C Input voltage Output current WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device’s electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within the recommended operating conditions. Operation outside these ranges may adversely affect reliability and could result in device failure. No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representative beforehand. 7 MB3828 ■ ELECTRICAL CHARACTERISTICS (Ta = +25°C, VCC = 5 V) Parameter Reference voltage block (Ref) Under voltage lockout circuit block (UVLO) Soft start block (CS) Symbol Min. Typ. Max. Unit 24 VREF = 0 mA Output voltage temperature regulation ∆VREF /VREF 24 Ta = –30°C to +85°C* — 0.5 — % Input stability Line 24 VCC = 4.6 V to 18 V — 1 10 mV Load stability Load 24 IO = 0 mA to –1 mA — 3 10 mV Short circuit output current IOS 24 VREF = 1 V –20 –10 –3 mA Threshold voltage VTH 4 VCC = 3.4 3.7 4.0 V Hysteresis voltage VH 4 — — 0.18 0.21 V Reset voltage VRST 4 — 1.7 2.1 — V Charge current ICS 4 — –2.8 –2.0 –1.2 µA 4 — 0.63 0.68 0.73 V 22 — –2.8 –2.0 –1.2 µA 0.50 0.75 1.34 ms 180 200 220 kHz — 1 — % 22 CSCP = 2200 pF Oscillator frequency fOSC 8, 11 RT = 130 kΩ Frequency temperature regulation 8, 11 Ta = –30°C to +85°C* ∆f/fdt 3.465 3.500 3.535 V VTH1 6 FB = 1.6 V, VD4 to VD0 = 00101 1.7784 1.8000 1.8216 V VTH2 6 FB = 1.6 V, VD4 to VD0 = 11010 2.4700 2.5000 2.5300 V VTH temperature regulation ∆VT/VT 6 Ta = –30°C to +85°C* — 0.5 — % Input bias current IB 5 –IN = 0 V –200 –50 — nA Voltage gain AV 6 DC 60 100 — dB Frequency bandwidth BW 6 AV = 0 dB* — 800 — kHz VOH 6 — 2.18 3.5 — V VOL 6 — — 0.8 1.0 V Output source current ISOURCE 6 FB = 1.6 V — –90 –45 µA Output sink current ISINK 6 FB = 1.6 V 3.0 12.0 — mA Output voltage * : Standard design value 8 Value VREF Threshold voltage Error amplifier block (Error Amp.) Condition Output voltage Threshold voltage VTH Short circuit Input source current ICSCP protection comparator block Short detection (SCP) tSCP interval Triangular wave oscillator block (OSC) Pin no. (Continued) MB3828 (Ta = +25°C, VCC = 5 V) Parameter PWM comparator blocks (PWM Threshold voltage Comp.1, 2) Symbol Pin no. Condition Typ. Max. Unit 8, 11 Duty cycle = 0% 1.2 1.3 — V VTH 8, 11 Duty cycle = Dtr — 1.86 2.0 V 85 90 95 % — V 8 RT = 130 kΩ VOH 8 OUT1 = –30 mA, VB = 5 V, CB = 20 V, VS = 15 V VOL 8 OUT1 = 30 mA, VB = 5 V, CB = 22 V, VS = 15 V Output voltage (main side) Output blocks (Drive1, 2) CB – 1.4 CB – 1.1 — VS + 1.1 VS + 1.4 V VB – 1.4 VB – 1.1 — V Output voltage (synchronized rectifier side) VOH 11 OUT2 = –30 mA, VB = 5 V VOL 11 OUT2 = 30 mA, VB = 5 V — 0.1 0.5 V Diode voltage VDIODE 13 IDIODE = 10 mA — 1.0 1.1 V VIH 24 IC operating mode 2.0 — 18 V VIL 24 IC standby mode 0 — 1.0 V ICTL 19 CTL = 5 V — 100 160 µA VTLOW 21 VD4 to VD0 setting, VSENSE = 0.88 × VD 0.90 × VD 0.92 × VD V VTHIGH 21 VD4 to VD0 setting, VSENSE = 1.08 × VD 1.10 × VD 1.12 × VD V Hysteresis voltage VH 21 3 30 50 mV Output leak current ILEAK 21 PWRGOOD = 5 V — — 40 µA Output voltage VOL 21 PWRGOOD = 1 mA — 0.06 0.4 V VTH 24 CS = — 0.05 0.07 V VIH 24 Discharge control ON 2.0 — 18 V VIL 24 Discharge control OFF 0 — 1.0 V IENB 7 ENB = 0 V –1.0 –0.05 — µA CTL input voltage Input current PWRGOOD comparator protection block (PWRGD) Min. VTL Dead time control Maximum duty cycle Dtr block (DTC) Control block (CTL) Value Threshold voltage Discharge control comparator (CS Threshold voltage Comp.) Discharge control ENB input voltage ON/OFF block (CTL LOGIC) Input current — (Continued) 9 MB3828 (Continued) (Ta = +25°C, VCC = 5 V) Parameter Threshold voltage Over voltage protection comparator block Hysteresis voltage (OVP) VSENSE pin input current Pin no. Condition VTH 8, 11 VSENSE = VD = 1.3 V VH 8, 11 ISENSE 20 , — VSENSE = 0 V Value Min. 1.15 × VD Typ. Max. 1.175 1.20 × VD × VD Unit V 3 30 50 mV –10 –0.1 — µA D/A input voltage VIH 14 to 18 — 2.0 — 18 V D/A (VD4 to VD0 D/A input voltage pin) (D/A) VIL 14 to 18 — 0 — 1.0 V Input current ID 14 to 18 VD4 to VD0 = 5 V — 0.05 1.0 µA Standby current ICCS 23 CTL = 0 V — 0 10 µA Power supply current ICC 23 — 4.0 6.0 mA General 10 Symbol — MB3828 ■ TYPICAL CHARACTERISTICS 5.0 Reference voltage vs. Power supply voltage characteristics 5.0 Ta = +25°C VB = 5 V Reference voltage VREF (V) Power supply current ICC (mA) Power supply current vs. Power supply voltage characteristics 4.0 3.0 2.0 1.0 0 4.0 3.0 2.0 1.0 0 0 5.0 10.0 15.0 20.0 25.0 0 4.0 8.0 12.0 16.0 20.0 Power supply voltage VCC (V) Power supply voltage VCC (V) VREF vs. Temperature characteristics Reference voltage, CTL pin current vs. Control voltage 3.55 3.50 3.45 3.40 –40.0 –20.0 5.0 0.0 20.0 40.0 60.0 Ta = +25°C VB = 5 V VREF 4.0 500.0 400.0 3.0 300.0 ICTL 2.0 200.0 1.0 100.0 Control pin current ICTL (µA) VCC = 16 V, VB = 5 V, RT = 130 kΩ Reference voltage VREF (V) Reference voltage VREF (V) 3.60 80.0 100.0 Temperature Ta (°C) 0 0 5.0 10.0 15.0 20.0 0 25.0 Control voltage VCTL (V) 3.60 VCC = 16 V, VB = 5 V, RT = 130 kΩ 3.55 3.50 3.45 3.40 –40.0 –20.0 0.0 20.0 40.0 60.0 80.0 100.0 Temperature Ta (°C) ERR threshold (2.0 V setting) vs. Temperature characteristics ERR threshold (2.0 V setting) (V) ERR threshold (3.5 V setting) (V) ERR threshold (3.5 V setting) vs. Temperature characteristics 2.04 VCC = 16 V, VB = 5 V, RT = 130 kΩ 2.02 2.00 1.98 196 1.94 –40.0 –20.0 0.0 20.0 40.0 60.0 80.0 100.0 Temperature Ta (°C) (Continued) 11 MB3828 ERR threshold (1.3 V setting) (V) ERR threshold (1.3 V setting) vs. Temperature characteristics 1.34 VCC = 16 V, VB = 5 V, RT = 130 kΩ 1.32 1.30 1.28 1.26 1.24 –40.0 –20.0 0.0 20.0 40.0 60.0 80.0 100.0 Temperature Ta (°C) Error Amp. gain, Phase vs. Frequency characteristics Error Amp. 40 30 φ Gain AV (dB) 20 10 180 90 45 AV 0 3V 135 0 –10 –45 –20 –90 –30 –135 –40 –180 1K 10 K 100 K 1M 240 kΩ 10 kΩ Phase φ (°) Ta = +25°C VCC = 16 V VB = 5 V IN 1 µF 2.4 kΩ VREF – + + OUT 10 kΩ 1.5 V 10 M Frequency f (HZ) (Continued) 12 MB3828 (Continued) Triangular wave oscillator frequency vs. Timing resistance characteristics Oscillator Frequency fosc (kHz) 220 VB = 5 V, RT = 130 kΩ 210 200 190 180 1000 VCC = 16 V, VB = 5 V 100 10 10 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 100 1000 Timing resistance RT (kΩ) Power supply voltage VCC (V) Triangular wave oscillator frequency vs. Temperature characteristics Oscillator frequency fosc (kHz) Oscillator frequency fosc (kHz) Triangular wave oscillator frequency vs. Power supply voltage characteristics 220 VCC = 16 V, VB = 5 V, RT = 130 kΩ 210 200 190 180 –40.0 –20.0 0.0 20.0 40.0 60.0 80.0 100.0 Temperature Ta (°C) 13 MB3828 ■ FUNCTION DESCRIPTION 1. Switching Regulator Function (1) Reference voltage circuit (Ref) The reference voltage circuit uses the voltage supply from the VCC pin (pin 23) to generate a temperature compensated reference voltage (≅ 3.5 V) for use as the reference voltage for the internal circuits of the IC chip. It is also possible to supply a reference voltage output of up to 1 mA to external circuits through the VREF pin (pin 24). (2) Triangular wave oscillator (OSC) The triangular wave form is generated using an on-chip frequency selection capacitor, plus the frequency selection resistance connected to the RT pin (pin 1). The triangular wave is input to the PWM comparator circuits on the IC. (3) Error amplifier (Error Amp.) The error amplifier circuit is used to detect the output voltage from the DC/DC converter for output as the PWM control signal. The in-phase input range covers the full range from 0 V to VCC – 0.9 V. By connecting a feedback resistance and capacitor between the FB pin (pin 6) and –IN pin (pin 5), it is possible to create any desired level of loop gain, thereby providing stable phase compensation to the system. Also, it is possible to prevent current spikes at power supply start-up by connecting a soft start capacitor to the CS pin (pin 4), the non-inverting input pin for Error Amp. The use of Error Amp. for soft start detection makes it possible for a system to operate on a fixed soft start time that is independent of the output load on the DC/ DC converter. (4) PWM comparators (PWM Comp.1, PWM Comp.2) PWM Comp.1 and PWM Comp.2 are voltage-pulse width converters that control output voltage according to input voltage. PWM Comp.1 controls the pulse width on the main-side output circuit, and PWM Comp.2 controls the pulse width on the synchronous rectifier side output circuit. The triangular wave generated by the triangular wave oscillator is compared with the output voltage from Error Amp., and during intervals when Error Amp. output is higher than the triangular wave, the main-side output transistor is switched on and the synchronous rectifier side output transistor is turned off. PWM Comp.1 is set to a maximum duty cycle of approximately 90%. (5) Output circuits (Drive1, Drive2) The output circuits on both the main-side and synchronous rectifier-side have a totem-pole configuration, and are capable of driving an external N-ch. MOS FET. (6) Power supply control circuit (CTL) This circuit is able to control power supply ON/OFF switching from the CTL pin (pin 19). (During standby mode, supply current is 0 µA TYP.) (7) DAC circuit (D/A) This circuit controls the output voltage to the CPU between 1.3 V and 3.5 V, as selected by the 5-bit (32-step) input signal information. The output voltage can be set in 100 mV steps between 3.5 V and 2.1 V, and in 50 mV steps between 2.05 V and 1.3 V. When all D/A input pins VD4 through VD0 (pin 18 through pin 14) are set to “H” level, the DC/DC converter output voltage is 0 V. 14 MB3828 2. Protection Functions (1) VCC under voltage lockout circuit (UVLO) Power surges at power-on, or momentary under-voltage situations can cause abnormal operation in the MB3828, which may lead to damage or deterioration in systems. This circuit prevents abnormal operation during times of low voltage by using the supply voltage to detect the level of the internal reference voltage, and fixes output pins OUT1 (pin 8) and OUT2 (pin 11) to “L” level. Once the supply voltage recovers to a level above the threshold voltage of the under voltage lockout circuit, operation is restored. (2) Timer-latch short-circuit protection circuit (SCP) This circuit detects the output voltage level from Error Amp. and activates the timer circuit, charging the external capacitor from the CSCP pin (pin 22) when Error Amp. output voltage level reaches or exceeds about 2.1 V. If Error Amp. output does not return to the normal voltage range before the capacitor voltage reaches about 0.68 V, the latch circuit is activated and the output pins (OUT1, OUT2) are held at “L” level. Once the protector circuit is activated, it can be reset by switching the power supply off and on again. (3) Overvoltage protection circuit (OVP) When the DC/DC converter output voltage (VO) exceeds the output voltage set by the VD4 to VD0 pins by more than +17.5%, the overvoltage protection circuit output signal goes to “H” level causing one output pin (OUT1) to be held at “L” level and the other output pin (OUT2) to be held at “H” level. (4) PWRGOOD comparator detection circuit (PWRGD) The PWRGOOD pin (pin 21) outputs an “H” level signal as long as the VSENSE pin (pin 20) is receiving the DC/DC converter output voltage (VO) within the range of 0.9 to 1.1 times the output voltage set by the VD4 to VD0 pins. 3. Soft Start/Discharge Control (1) Soft start circuit (CS) Connecting a capacitor to the CS pin (pin 4) prevents the inrush current at power turnon. Using an Error Amp. for detecting the soft error allows the soft start time to be initiated independent of output load from the DC/DC converter. (2) Discharge control ON/OFF circuit (CTL LOGIC) Entering an “L” level signal at the CTL pin while an “H” level signal is input at the ENB pin causes the discharge control ON/OFF circuit (CTL LOGIC) to switch the soft start circuit (CS) from charging to discharging. The resistance (RS) connected to the RS pin (pin 2) charges the soft start capacitor (CS), so that Error Amp. provides control over the DC/DC converter output voltage in the same way as during a soft start. This makes it possible to control voltage drop independently of output load. When the CS pin voltage reaches the discharge control comparator circuit (CS Comp.) threshold voltage (≅ 50 mV), the discharge control is canceled. When an “L” level signal is input at the ENB pin (pin 7), the DC/DC converter output voltage discharge time control is switched OFF. 15 MB3828 ■ METHOD OF SETTING THE SOFT START TIME At startup of the MB3828, the capacitor (CS) connected to the CS pin begins charging. This produces a soft start, by providing output voltage from Error Amp. that is proportional to the CS pin voltage regardless of the DC/DC converter load current. Soft start time (time to output setting voltage VD) tS (sec) ~ VD × CS (µF) 2 (µA) ■ TIME SETTING BY SHORT DETECTION When load conditions change rapidly with the reduced output voltage, as when a load fault occurs, the Capacitor Cscp connected to the CSCP pin (pin 22) is charged to threshold voltage (VTH:=0.68V) and sets a latch, the external FET is turned off (inactive interval 100%). Short detection time tPE (sec) ~ 0.68 × CSCP (µF) / 2 (µA) ■ OSCILLATOR FREQUENCY SETTING The oscillator frequency can be set by connecting resistance to the RT pin (pin 1). Oscillator frequency fOSC (kHz) ~ 26250 / RT (kΩ) ■ METHOD OF SETTING THE DISCHARGE TIME • An “L” level CTL signal while the ENB pin is set to “H” level causes the resistance (RS) connected to the RS pin to discharge electrical charge the capacitor (CS) connected to the CS pin, causing the output voltage to fall gradually regardless of the DC/DC converter load current. Discharge time (time to 0.05 V output voltage) toff (msec) ~ RS (kΩ) × CS (µF) × ln ( VD ) VTH (CS COMP) • As long as the ENB pin is set to “L” level, the discharge control function is switched OFF. ■ D/A BLOCK VD4 to VD0 SWITCHING • Switching of the VD4 to VD0 pin signal during the MB3828 operation may cause transient fluctuation in output voltage from the DC/DC converter. The resulting voltage instability may cause an “L” level from the PWRGOOD block, activating the OVP protection and shutting off the output from the DC/DC converter. To switch VD4 to VD0 pin settings, first input an “L” level control signal to the CTL pin to place the MB3828 in standby status. • When all VD4 to VD0 pin signals are set to “H” level, the DC/DC converter output is switched OFF. 16 MB3828 ■ PWRGOOD COMPARATOR CIRCUIT, OVP CIRCUIT OPERATION TIMING CHART CTL signal DC/DC output voltage VD × 1.1 VD × 0.9 VD × 1.175 VD × 0.9 PWRGOOD signal OUT1 signal OUT2 signal Operation when ENB signal is “High”. VD × 1.175 DC/DC output voltage VD × 1.1 VD × 0.9 Hysteresis voltage 30 mV Hysteresis voltage 30 mV Hysteresis voltage 30 mV PWRGOOD OUT2 17 MB3828 ■ CTL LOGIC CIRCUIT OPERATION TIMING CHART CTL signal ENB signal VREF output voltage CS pin voltage DC/DC output voltage 0.05 V ts toff ■ DC/DC CONVERTER INPUT VOLTAGE (Vin) AND VB VOLTAGE SETTING The voltage at the CB pin is bootstrapped from the VS pin voltage by an amount equivalent to the VB pin voltage, as a result of the bootstrap capacitance (CB) between the CB pin and VS pin. Therefore, either the Vin voltage or VB pin voltage should be adjusted so that the sum of the DC/DC converter block input voltage Vin plus the VB pin voltage does not exceed the recommended operating conditions for the CB pin boot voltage (VCB). VB 13 *1 10 Drive 1 8 9 DC/DC converter block CB *2 OUT1 VS CB Vin VB VO Drive 2 OUT2 *2 11 PGND 12 *1: To connect the external low VF diode (Schottky barrier diode) makes VB pin voltage drop reduced and then can perform the higher efficiency. *2: The switching noise can be reduced (0Ω to 5Ω) by connecting the resistance when the external MOSFET gate input capacitance (Ciss) is large, caused by the external MOSFET gate drive current limiting resistance. 18 MB3828 ■ DC/DC CONVERTER SWITCHING OPERATION WAVEFORMS <VCC = 5 V, VB = 5 V, Vin = 15V> VD4–VD0 = 00101 (1.8 V) load: 2 A fosc = 200 kHz setting VS (V) 20 OUT1 (V) OUT2 (V) 15 60 30 50 25 10 40 20 5 30 15 0 20 10 −5 10 5 0 0 −10 −5 VS 5 V 10 V OUT1 OUT2 1 µs 5V 0 4 2 6 8 10 t (µs) expansion VS (V) 1 OUT1 (V) OUT2 (V) 0.5 60 30 50 25 0 40 20 −0.5 30 15 −1 20 10 10 5 0 0 −10 −5 10 V 500 mV 500 mV 10 V VS VS OUT1 OUT1 OUT2 5V 0 0.2 OUT2 5V 100 ns 0.4 0.6 0.8 Synchronous rectifier length: 250 ns (typ) OUT1 tf: 60 ns (typ) OUT2 tr: 130 ns (typ) 1.0 0 t (µs) 100 ns 0.2 0.4 0.6 0.8 1.0 t (µs) Synchronous rectifier length: 200 ns (typ) OUT1 tr: 130 ns (typ) OUT2 tf: 100 ns (typ) 19 20 VIN 15 V VB 5V 5 2 VD4 18 VD3 17 VD2 16 VD1 15 VD0 14 4 4700 pF CS 100 kΩ RS 12000 pF FB 6 10 kΩ 2.4 kΩ –IN D/A (5-bit) CS – + + OSC Error Amp. VSENSE C (40 pF) 20 1 RT 130 kΩ VSCP VB – + – + SCP Comp. VCS PWM Comp.2 Over voltage protection (17.5%) OVP PWM + Comp.1 + DTC – POWERGOOD PWRGD (±10%) PWRGOOD 21 CS Comp. 22 2200 pF CSCP SCP – + 4.7 kΩ UVLO 24 0.1 µF VREF (3.5 V) 3 SGND Power ON/OFF CTL bias Ref bias CTL LOGIC Drive 2 Drive 1 10 PGND OUT2 0.1 µF VS OUT1 CB 23 VCC 100 µF Si4410DY 0.1 µF 4.7 µF VO 150 µF × 6 7.6 µH RB051L - 40 (24 pins) 220 µF Si4410DY VS Note: Si4410DY : Product of Siliconix Co. RB415D : Product of ROHM Co., LTD. RB051L-40 : Product of ROHM Co., LTD. 0.1 µF 7 ENB 19 CTL 12 11 9 8 VB RB415D 13 MB3828 ■ APPLICATION EXAMPLE Output voltage setting signals MB3828 ■ REFERENCE DATA Conversion efficiency vs. Load current characteristics (Output voltage = 1.8 V ) 100 95 Conversion efficiency η (%) 90 85 80 75 Vin = 15 V Vin = 11 V Vin = 22 V 70 Vin = 7 V 65 60 55 50 0.01 0.10 1.00 10.00 Load current (A) Conversion efficiency vs. Load current characteristics (Output voltage = 3.3 V ) 100 95 Conversion efficiency η (%) 90 85 80 Vin = 15 V Vin = 22 V Vin = 11 V 75 Vin = 7 V 70 65 60 55 50 0.01 0.10 1.00 10.00 Load current (A) (Continued) 21 MB3828 Transient response for CTL ON/OFF < Output = 1.8 V, nonload > CS = 4700 pF ENB = VCC 1V VO (V) 3 2 1 0 10 CTL (V) 5 0 2 mS 5V 0 4 8 12 16 20 t (ms) Transient response for CTL ON/OFF < Output = 3.3 V, nonload > VO (V) CS = 2700 pF ENB = VCC 1V 3 2 1 0 10 CTL (V) 5 0 2 mS 5V 0 4 8 12 16 20 t (ms) (Continued) 22 MB3828 (Continued) Transient response for CTL ON/OFF (Output = 1.8 V) VO (mV) 100 50 mV 50 0 IO(A) −50 4 2 0 −2 100µs 10 mV 0 200 400 600 800 1000 t (µs) Transient response for load abrupt change (Output = 3.3 V) VO (mV) 100 50 mV 50 0 IO(A) −50 4 2 0 −2 100µs 10 mV 0 200 400 600 800 1000 t (µs) 23 MB3828 ■ USAGE PRECAUTIONS 1. Device settings must not exceed absolute maximum ratings. Usage under conditions exceeding absolute maximum ratings may permanently damage LSI devices. Note also that in normal operation usage within recommended operating conditions is preferred, and that the reliability of LSI devices may be adversely affected when used outside these conditions. 2. Devices should be used within recommended operating conditions. Recommended operating conditions are recommended values within which the LSI device is warranted to operate normally. Rated values of electrical characteristics are warranted within the range of recommended operating conditions and within the conditions listed in the condition column for each parameter. 3. Printed circuit board ground lines should be designed in consideration of common impedance values. 4. Observe precautions against static electricity. • Containers in which semiconductors are placed should either be protected against static electricity, or be of conductive material. • After mounting of devices, use conductive bags or conductive containers when storing or transporting printed circuit boards. • Working surfaces, tools and instruments should be properly grounded. • Workers should be grounded by a ground line with 250 kΩ to 1 MΩ resistance in series between the worker and ground. ■ ORDERING INFORMATION Part number MB3828 PFV-G-BND 24 Package 24-pin Plastic SSOP (FPT-24P-M03) Remarks MB3828 ■ PACKAGE DIMENSION 24-pin Plastic SSOP (FPT-24P-M03) *: These dimensions do not include resin protrusion. +0.20 * 7.75±0.10(.305±.004) 1.25 –0.10 +.008 .049 –.004 (Mounting height) 0.10(.004) * 5.60±0.10 INDEX 0.65±0.12(.0256±.0047) (.220±.004) +0.10 C 1994 FUJITSU LIMITED F24018S-2C-2 6.60(.260) NOM "A" +0.05 0.22 –0.05 0.15 –0.02 +.004 –.002 .006 –.001 .009 7.15(.281)REF 7.60±0.20 (.299±.008) Details of "A" part +.002 0.10±0.10(.004±.004) (STAND OFF) 0 10° 0.50±0.20 (.020±.008) Dimensions in mm (inches) 25 MB3828 FUJITSU LIMITED For further information please contact: Japan FUJITSU LIMITED Corporate Global Business Support Division Electronic Devices KAWASAKI PLANT, 4-1-1, Kamikodanaka Nakahara-ku, Kawasaki-shi Kanagawa 211-8588, Japan Tel: 81(44) 754-3763 Fax: 81(44) 754-3329 http://www.fujitsu.co.jp/ North and South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street San Jose, CA 95134-1804, USA Tel: (408) 922-9000 Fax: (408) 922-9179 Customer Response Center Mon. - Fri.: 7 am - 5 pm (PST) Tel: (800) 866-8608 Fax: (408) 922-9179 http://www.fujitsumicro.com/ Europe FUJITSU MIKROELEKTRONIK GmbH Am Siebenstein 6-10 D-63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122 http://www.fujitsu-ede.com/ Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE LTD #05-08, 151 Lorong Chuan New Tech Park Singapore 556741 Tel: (65) 281-0770 Fax: (65) 281-0220 http://www.fmap.com.sg/ F9903 FUJITSU LIMITED Printed in Japan 26 All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU sales representatives before ordering. The information and circuit diagrams in this document are presented as examples of semiconductor device applications, and are not intended to be incorporated in devices for actual use. Also, FUJITSU is unable to assume responsibility for infringement of any patent rights or other rights of third parties arising from the use of this information or circuit diagrams. FUJITSU semiconductor devices are intended for use in standard applications (computers, office automation and other office equipment, industrial, communications, and measurement equipment, personal or household devices, etc.). CAUTION: Customers considering the use of our products in special applications where failure or abnormal operation may directly affect human lives or cause physical injury or property damage, or where extremely high levels of reliability are demanded (such as aerospace systems, atomic energy controls, sea floor repeaters, vehicle operating controls, medical devices for life support, etc.) are requested to consult with FUJITSU sales representatives before such use. The company will not be responsible for damages arising from such use without prior approval. Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under the Foreign Exchange and Foreign Trade Law of Japan, the prior authorization by Japanese government will be required for export of those products from Japan.