MB3785A Fujitsu, MB3785A Datasheet
MB3785A
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MB3785A Summary of contents
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... MB3785A DESCRIPTION The MB3785A is a PWM-based 4-channel switching regulator controller featuring high-precision, high-frequency capabilities. All of the four channels of circuits allow their outputs to be set in three modes: step-down, step-up, and inverted. The third and fourth channels are suited for DC motor speed control. ...
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... MB3785A PIN ASSIGNMENT Cb1 48 Ca1 1 Cb2 2 Ca2 3 DTC1 4 FB1 5 IN1 (E) 6 IN1 (E) 7 IN1 (C) 8 DTC2 9 FB2 10 IN2 (E) 11 IN2 ( IN2(C) (Note) The alphabetic characters in parenthesis indicate the following input pins. (C) : comparator (E) : error amp 2 (TOP VIEW) OUT1 OUT2 GND OUT3 VE1 ...
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... Ca4 and the Cb4 terminals, then set the output transistor OFF-cur- 37 Cb4 — rent. 30 +IN4(E) I CH4 error amp non-inverted input terminal. CH4 31 –IN4(E) I CH4 error inverted input terminal. 32 FB4 O CH4 error amp output terminal. 29 –IN4(C) I CH4 comparator inverted input terminal. MB3785A Description (Continued) 3 ...
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... MB3785A (Continued) Pin No. Symbol I/O 33 DTC4 I CH4 38 VE4 I 39 OUT4 O — 14 OSC IN — 15 OSC OUT — — — — GND — REF 23 SCP — 20 CTL1 I 21 CTL2 I 22 CTL3 I 4 Description CH4 dead time control terminal. CH4 output current setting terminal. ...
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... DTC 1.2 V Comparator 3 V REF Under Voltage S R Triangular-Wave Lock-out SR Latch Oscillator Circuit Protection Circuit OSC OSC OUT Ceramic Resonator MB3785A Ca1 1 Cb1 OFF Current Setting OUT1 46 47 2.5 V VE1 3 Ca2 2 Cb2 OFF Current Setting OUT2 44 43 2.5 V VE2 34 Ca3 ...
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... MB3785A FUNCTIONAL DESCRIPTION 1. Switching Regulator Function (1) Reference voltage circuit The reference voltage circuit generates a temperature-compensated reference voltage ( : = 2.50 V) using the voltage supplied from the power supply terminal (pin 18). This voltage is used as the operating power supply for the internal circuits of the IC. The reference voltage can also be supplied to an external device from the V terminal (pin 19) ...
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... Channel Control Function The MB3785A allows the four channels of power supply circuits to be controlled independently. Set the voltage levels on the CTL1 (pin 20), CTL2 (pin 21), and CTL3 (pin 22) terminals to turn the circuit of each channel “ON” or “OFF”, as listed below. Table 1 Channel by Channel On/Off Setting Conditions. ...
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... MB3785A ABSOLUTE MAXIMUM RAGINGS (See WARNING) Parameter Power supply voltage Control input voltage Power dissipation Operating ambient temperature Storage temperature *: The packages are mounted on the epoxy board (4 cm 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. ...
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... — ICM V — tPC V — STB V — — lbpc 300 pF 6.2 k OSC –30°C to +85°C dT MB3785A ( + Value Unit Min. Typ. Max. 2.500 2.525 V –2 ±0 –10 – –10 – –25 –8 –3 mA — 2.72 — V — 2.60 — ...
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... MB3785A (Continued) Parameter Input offset voltage Input bias current Common mode input voltage range Voltage gain Frequency bandwidth Input threshold voltage Input bias current Latch mode source current Latch input voltage Input threshold voltage Input bias current Latch mode source current ...
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... Control voltage V (V) CTL1 2. Reference voltage vs. Supply voltage Reference voltage vs. Ambient temperature 2. 2.54 4 2.52 3 2. 2.46 2. Ambient temperature Control current vs. Control voltage 500 400 300 200 100 MB3785A Ta= Supply voltage V ( CTL1 1mA 100 Control voltage V (V) CTL1 (Continued) 11 ...
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... MB3785A (Continued) 7. Triangular wave maximum amplitude voltage vs. Timing capacitance 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0 Timing capacitance C 9. Triangular wave cycle vs. Timing capacitance 100 0.5 0 Timing capacitance C 11. Rate of change in triangular wave frequency vs. Ambient temperature (Not using ceramic resonator) ...
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... Power dissipation vs. Ambient temperature 1000 800 600 LQFP 550 400 200 0 –30 – Ambient temperature 14. Error amp maximum output voltage vs. Frequency 3.0 180 2 100 500 Triangular wave frequency f OUT Error amp 60 80 100 MB3785A 100 k 500 (Hz) OSC 13 ...
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... MB3785A METHODS OF SETTING THE OUTPUT VOLTAGE 1. Method of Connecting CH1 and CH2: When Output Voltage (V V REF Method of Connecting CH1 and CH2: When Output Voltage (V V REF OUT REF R V – – REF – – – – V OUT ) is Positive Negative REF 1 ...
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... Method of Connecting CH3 and CH4: When Output Voltage (V V REF Method of Connecting CH3 and CH4: When Output Voltage (V V REF OUT REF – REF – – – – V OUT MB3785A ) is Positive Negative REF 15 ...
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... Figure 1. CH1 to CH4 Output Circuit Drive transistor C B OFF-current setting block Figure 3. Voltage and Current Waveforms on Output Pin (CH1 0 Figure 2. Output Current Waveform OFF-current 0 ON-current Figure 4. Measuring Circuit Diagram 200 ns 1000 pF 1 MB3785A 1.2 1.6 2.0 ON-current OFF-current pin 8 2.7 46 570 pin 82 ...
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... Simultaneously, the dead time is extended to 100% and the output voltage on the SCP terminal (pin 23) is held “L” result, the S-R latch input is closed and C Figure 5. Protection Latch Circuit Comparator 1 – Comparator 2 – – Q Comparator – Comparator comparator Latch U.V.L MB3785A (externally fitted to the SCP PE is discharged. 2.5 V OUT PWM 17 ...
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... MB3785A TREATMENT WHEN NOT USING SCP When you do not use the timer/latch-actuated short-circuiting protection circuit, connect the SCP terminal (pin 23) to GND with the shortest distance possible. Also, connect the comparator’s input terminal for each channel to the V terminal (pin 18). ...
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... Figure 8. When Using Ceramic Resonator Ceramic resonator terminal (pin 15) open. This makes it possible OUT and OSC OSC OUT Open and OSC as shown below, you can set the oscillation IN OUT are required. Determine the values OSC OSC OUT MB3785A and R so that the oscillation ...
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... MB3785A <Precautions> When the oscillation rise time at power switch-on is compared between a ceramic and a crystal resonator known that the crystal resonator is about 10 to 100 times slower to rise than the ceramic resonator. Therefore, when a crystal resonator is used, system operation as a switching regulator at power switch-on becomes unstable ...
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... V and triangular-wave maximum voltage : = 1 given below. 1.9 – Duty (OFF) 100 [%], V 0.6 When you do not use these DTC terminals, connect them to V voltage so you can easily set the output transistor’s REF R 2 100 [%], REF Figure 10. When Not Using DTC REF REF MB3785A DTC1 (DTC2) 21 ...
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... MB3785A Figure 11. When Using DTC to Set Dead Time DTC3 (DTC4) Vdt R 2 <Precautions> When you use a ceramic resonator, pay attention when setting the dead time because the triangular-wave amplitude is determined by the values Figure 12. When Not Using DTC REF and REF DTC3 ...
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... Soft start time (time until output ON duty 1.6 ts ( 2.5 Figure 13. Setting Soft Start for CH1 and CH2 19 V REF Cdt DTC1 Rdt (DTC2) 50%) 0.446 C ( 50%) ) 1.022 C ( Figure 14. Setting Soft Start for CH3 and CH4 Rdt Cdt MB3785A 19 V REF DTC3 (DTC4) 23 ...
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... MB3785A It is also possible to set soft start simultaneously with the dead time by configuring the DTC terminals as shown below. For figure 15 Soft start time (time until output ON duty For figure 16 Soft start time (time until output ON duty Figure 15. Setting Dead Time and Soft Start ...
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... A smoothing capacitor with a low ESR reduces system stability. Use care when using low ESR electrolytic capacitors (OS-CON TM ) and tantalum capacitors. Note: OS-CON is the trademark of Sanyo Electnic Co., Ltd Gain vs. Frequency ( ( 100 1 k Frequency f (Hz) DC/DC Converter Basic Circuit Phase vs. Frequency 0 90 ( (1) 180 10 k 100 k 10 MB3785A (2) ( 100 100 k Frequency f (Hz) 25 ...
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... MB3785A Reference data If an aluminum electrolytic smoothing capacitor ( 1 replaced with a low ESR electrolytic capacitor (OS-CON 0.2 ), the phase margin is reduced by half (see Fig. 37 and 38). DC/DC Converter A FB DC/DC Converter 5 V output Gain vs. Phase 100 1 k Figure 38 DC/DC Converter 5 V output Gain vs. Phase ...
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... CH1 OUT 46 1000 pF 47 250 1000 CH2 OUT 44 1000 pF 43 250 1000 CH3 OUT 40 1000 pF 41 250 1000 OUT CH4 39 1000 pF 38 250 GND 300 pF CTL1 CTL2 CTL3 R T 6.2 k Output Control Signals MB3785A 8 motor 8 motor 8 ...
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... Ground the workbenches, tools, and measuring equipment to earth. • Make sure that operators wear wrist straps or other appropriate fittings grounded to earth via a resistance of 250 placed in series between the human body and earth. ORDERING INFORMATION Part number MB3785APFV 28 Package 48-pin plastic LQFP (FPT-48P-M05) ...
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... Details of "A" part 0.08(.003) 13 "A" 0.50±0.20 0.08(.003) M (.020±.008) 0.60±0.15 (.024±.006) MB3785A +0.20 1.50 –0.10 (Mounting height) +.008 .059 –.004 0.10±0.10 (.004±.004) 0°~8° (Stand off) 0.25(.010) ...
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... MB3785A FUJITSU LIMITED 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, ...