MB3889

Manufacturer Part NumberMB3889
Description2-channel Dc/dc Converter Ic With Overcurrent Protection Symmetrical-phase Type
ManufacturerFujitsu Microelectronics, Inc.
MB3889 datasheet
 


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FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP
For Power Supply Applications (General Purpose DC/DC Converter)
2-Channel DC/DC Converter IC
with Overcurrent Protection Symmetrical-Phase Type
MB3889
DESCRIPTION
The MB3889 is a symmetrical-phase type of two-channel, DC/DC converter IC using pulse width modulation
(PWM) , incorporating an overcurrent protection circuit (requiring no current sense resistor) and an overvoltage
protection circuit. Providing high output driving capabilities, the MB3889 is suitable for down-conversion.
The MB3889 adopts both synchronous rectification to provide high efficiency and symmetrical phasing (two anti-
phase triangular waves) which contributes to making the input capacitor small.
The MB3889 contains a 5-volt regulator resulting in a reduced number of components used. It also contains a
variety of protection features which output the protection status upon detection of an overvoltage or overcurrent
while reducing the number of external protective devices required.
The result is an ideal built-in power supply for driving products with high speed CPU’s such as home TV game
devices and notebook PC’s.
This product is covered by US Patent Number 6,147,477.
FEATURES
• Built-in timer-latch overcurrent protection circuit (requiring no current sense resistor)
• Built-in timer-latch overvoltage protection circuit
• Synchronous rectification system providing high efficiency
• Power supply voltage range: 5.5 V to 18 V
• PWRGOOD terminals (open-drain) to output the protection status
• Symmetrical-phase system reducing the input capacitor loss
• Built-in channel control function
• Reference voltage: 3.5 V
PACKAGE
1
30-pin plastic TSSOP
(FPT-30P-M04)
DS04-27229-2E
(Continued)

MB3889 Summary of contents

  • Page 1

    ... The MB3889 adopts both synchronous rectification to provide high efficiency and symmetrical phasing (two anti- phase triangular waves) which contributes to making the input capacitor small. The MB3889 contains a 5-volt regulator resulting in a reduced number of components used. It also contains a variety of protection features which output the protection status upon detection of an overvoltage or overcurrent while reducing the number of external protective devices required. The result is an ideal built-in power supply for driving products with high speed CPU’ ...

  • Page 2

    ... MB3889 (Continued) • Error amplifier threshold voltage: 1.23 V • Support for frequency setting using an external resistor (Frequency setting capacitor integrated) • Oscillation frequency range: 100 kHz to 500 kHz • Built-in circuit for load-independent soft-start and discharge control • Built-in totem-pole output for Nch MOS FET ...

  • Page 3

    ... PIN ASSIGNMENT INE1 : 1 FB1 : 2 CS1 : 3 N. CTL : 6 SGND : 7 VREF : 8 CTL1 : 9 CTL2 : 10 CSCP : 11 PWRGOOD : 12 CS2 : 13 FB2 : 14 INE2 : 15 (TOP VIEW CB1 29 : OUT1 VS1 27 : OUT2 PGND1 25 : ILIM1 24 : VCC 23 : ILIM2 N. PGND2 19 : OUT2 VS2 17 : OUT1 CB2 (FPT-30P-M04) MB3889 3 ...

  • Page 4

    ... MB3889 PIN DESCRIPTION Pin No. Symbol I/O 1 INE1 I 2 FB1 O 3 CS1 4 N. CTL I 7 SGND 8 VREF O 9 CTL1 I 10 CTL2 I 11 CSCP 12 PWRGOOD O 13 CS2 14 FB2 O 15 INE2 I 16 CB2 17 OUT1 VS2 19 OUT2 PGND2 21 N. ILIM2 I 24 VCC ...

  • Page 5

    ... H: at OVP H: at OCP H: at SCP protection operation R 3.0 V CT1 1 Error amp reference 3.0 V bias 1.23 V CT2 1.8 V OSC VREF VR1 VREF SGND MB3889 5 CB1 29 OUT1-1 28 VS1 27 OUT2-1 26 PGND1 25 ILIM1 16 CB2 17 OUT1-2 18 VS2 19 OUT2-2 20 PGND2 23 ILIM2 ...

  • Page 6

    ... MB3889 ABSOLUTE MAXIMUM RATINGS Parameter Symbol Power-supply voltage V CC Boot voltage V CB Output current I O Peak output current I OP Power dissipation P D Storage temperature T STG * : The packages are mounted on the dual-sided epoxy board (10 cm WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc ...

  • Page 7

    ... CTL terminal V PWRGOOD terminal Duty Duty) OSC f OSC VREF terminal REF C VB terminal SCP R LIM Ta MB3889 Value Unit Min Typ Max 5 1 REF ...

  • Page 8

    ... MB3889 ELECTRICAL CHARACTERISTICS Parameter Symbol Output voltage 1. Reference Voltage Input stability Block [REF] Load stability Short-circuit output current 2. Bias Voltage Output voltage Block [VB] Oscillation 3. Triangular frequency Waveform Frequency/ Oscillator temperature Block [OSC] variation Threshold 4. Undervolt- voltage age (VCC) Lockout Circuit Hysteresis ...

  • Page 9

    ... OL1 OUT2 0 V, 19, 27 Duty Duty) OSC OUT2 5.1 V, 19, 27 Duty Duty) OSC MB3889 0 mA, VREF 0 mA Value Unit Min Typ Max 1.221 1.230 1.239 V 1.218 1.230 1.242 V 730 110 nA 60 100 dB 1.5* MHz 3 ...

  • Page 10

    ... MB3889 (Continued) Parameter Output voltage (synchronous rectification side) Diode voltage 13. Output Block [Drive] Dead time Output ON condition Output OFF 14. Control condition Block Output ON (CTL, CTL1, condition CTL2) Output OFF [CTL] condition Input current Standby current 15. General Power-supply current *: Standard design value ...

  • Page 11

    ... V 1.0 0.5 0.0 0.5 1.0 1.5 2 Ambient temperature Triangular Wave Oscillation Frequency 5 1000 100 MB3889 CTL 5 V VREF (V) CC VCC 12 V CTL 5 V VREF 100 vs. Timing Resistor Ta +25 C VCC ...

  • Page 12

    ... MB3889 Triangular Wave Oscillation Frequency vs. Power Supply Voltage 330 325 320 315 310 305 300 295 290 285 280 275 270 Power supply voltage V Error Amplifier Threshold Voltage vs. Ambient Temperature 1.244 1.242 1.240 1.238 1.236 1.234 1.232 1.230 1.228 1.226 1 ...

  • Page 13

    ... Power Dissipation vs. Ambient Temperature 1600 1400 1390 1200 1000 800 600 400 200 Ambient temperature MB3889 100 13 ...

  • Page 14

    ... MB3889 FUNCTIONS 1. DC/DC Converter Functions (1) Reference voltage block (Ref) The reference voltage circuit generates a temperature-compensated reference voltage (typically 3.5 V) using the voltage supplied from the power supply terminal (pin 24) . The voltage is used as the reference voltage for the IC’s internal circuitry. The reference voltage can be used to supply a load current external device through the VREF terminal (pin 8) ...

  • Page 15

    ... CTL1 terminal (pin 9) and CTL2 terminal (pin 10) to the “L” level. (See “2. Setting Time Constant for Timer-Latch Short-Circuit Protection Circuit” in Channel On/Off Setting Conditions Power CH1 CH2 OFF OFF OFF ON OFF OFF ON ON OFF ON OFF ABOUT TIMER-LATCH PROTECTION CIRCUIT.) ABOUT TIMER-LATCH PROTECTION CIRCUIT.) MB3889 VB PWRGOOD OFF OFF ...

  • Page 16

    ... MB3889 (4) Timer-latch overvoltage protection circuit block (OVP) When the overvoltage detection comparator (OVP Comp.) provided for each channel detects the DC-DC con- verter’s output voltage level exceeding its threshold voltage, the timer-latch overvoltage protection circuit actuates the timer circuit and starts charging the capacitor CSCP connected to the CSCP terminal (pin 11). If the over- voltage remains applied beyond the predetermined period of time, the circuit sets the latch to turn off the FET on the main side of each channel while setting the PWRGOOD terminal (pin 12) to the “ ...

  • Page 17

    ... CS1 3 SETTING THE TRIANGULAR OSCILLATION FREQUENCY The triangular oscillation frequency is determined by the timing capacitor connected to the timing resistor (R connected to the RT terminal (pin 5). Triangular oscillation frequency: f OSC 14100 f (kHz OSC 1.23 Error Amp V ( 1.23 V < CH1, CH2 > MB3889 (R1 R2 ...

  • Page 18

    ... MB3889 SETTING THE SOFT-START AND DISCHARGE TIMES To prevent rush currents when the IC is turned on, you can set a soft-start by connecting soft-start capacitors (C and the CS1 terminal (pin 3) for channel 1 and the CS2 terminal (pin 13) for channel 2, respectively Setting the each control terminals (CTL1 and CTL2) from “L” to “OPEN” switches SW1 and SW2 from ...

  • Page 19

    ... When the soft-start function is not used, the CS1 terminal (pin 3) and CS2 terminal (pin 13) should be left open. < Operation Without Soft-start Setting > L priority 1.23 V VREF 3 A 100 K 10 Buff A SW1 (SW2 CTL1 <Soft-start circuit> 3 CS1 13 CS2 MB3889 Error Amp Soft-start Discharge 19 ...

  • Page 20

    ... MB3889 ABOUT TIMER-LATCH PROTECTION CIRCUIT 1. Setting Timer-Latch Overcurrent Protection Detection Current The overcurrent protection circuit is actuated upon completion of the soft-start period. When an overcurrent flows, the circuit detects the increase in the voltage between the main-side FET’s drain and source using the main-side FET ON resistor (RON), actuates the timer circuit, and starts charging the capacitor CSCP connected to the CSCP terminal (pin 11) ...

  • Page 21

    ... CTL1 terminal (pin 9) and CTL2 terminal (pin 10) to the “L” level. (FB2 INE2) INE1 R2 CSCP <Timer-latch short-circuit protection circuit> FB1 2 15 Error 1 Amp 1.23 V SCP Comp. 3 CTL CTL1 CTL2 11 VREF S R UVLO Latch Latch2 MB3889 PWRGOOD 12 21 ...

  • Page 22

    ... MB3889 3. Setting Overvoltage Detection by the Timer-Latch Overvoltage Protection Circuit An overvoltage output from the DC-DC converter can be detected by connecting external resistors from the DC- DC converter output to the noninverted input terminal (-INE1 terminal (pin 1) and -INE2 terminal (pin 15)) of the overvoltage comparators (OVP Comp. 1 and 2). ...

  • Page 23

    ... Operation Without Using the CSCP Terminals TREATMENT OF UNUSED PWRGOOD TERMINALS When the PWRGOOD terminal is not used, the PWRGOOD terminal (pin 12) should be shorted or open to the SGND terminal. <Operation Without Using the PWRGOOD Terminals> 25 ILIM1 23 ILIM2 7 SGND 7 SGND 11 CSCP 7 SGND "Open" 12 PWRGOOD 12 PWRGOOD MB3889 > 23 ...

  • Page 24

    ... MB3889 OUTPUT STATES DURING PROTECTION CIRCUIT OPERATION The table below lists the output states with each protection circuits actuated. Output terminal Protection circuit Overcurrent protection circuit Short-circuit protection Overvoltage protection circuit Under voltage lockout protection circuit RESETTING THE LATCH OF EACH PROTECTION CIRCUIT When the overvoltage, overcurrent, or short-circuit protection circuit detects each abnormality, it sets the latch to fix the output at the " ...

  • Page 25

    ... B (V) I (A) V ( CB1 Crss2 Crss1 OUT1 Ciss1 VS1 Ciss2 OUT2-1 27 PGND1 26 t Bias current Ibias1 : = Bias current Ibias1 : = MB3889 O1 25 ...

  • Page 26

    ... MB3889 Power Consumption vs. Input Voltage (Qg Parameter) 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Power Consumption vs. Input Voltage (f 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Input voltage Vin ( Input voltage Vin ( ...

  • Page 27

    ... V CT1 1 Error amp reference 3 bias 1.23 V CT2 VCC 1.8 V Power OSC VREF VR1 ON/OFF CTL VREF SGND C15 0.1 F MB3889 CB1 0 V/ OUT1 VS1 C25 C18 C4 C5 0.1 0.1 F OUT2 150 F F PGND1 ...

  • Page 28

    ... MB3889 PARTS LIST COMPONENT ITEM Q1, Q2 Dual FETKY D1, D2 Diode L1, L2 Coil C3, C6 Ceramics Condenser C4 OS-CON TM C5, C8 Ceramics Condenser C7 OS-CON TM C9 Ceramics Condenser C10 Ceramics Condenser C11, C13 Ceramics Condenser C12 Ceramics Condenser C14 Ceramics Condenser C15, C16 Ceramics Condenser C17, C18 ...

  • Page 29

    ... Load current IL (A) Vin = 8.5 V Vin = 10 V Vin = 3.3 V output CTL 5 V CTL1 Open CTL2 “L” level 1 10 Vin = 8.5 V Vin = 10 V Vin = output CTL 5 V CTL1 “L” level CTL2 Open 1 10 MB3889 (Continued) 29 ...

  • Page 30

    ... MB3889 V ( 120 160 200 240 280 320 30 Switching Waveform (CH1 Expansion Expansion ( 120 160 200 240 280 320 360 400 360 400 ...

  • Page 31

    ... VIN CTL “ ” CTL1 L Open CTL2 Expansion V ( 120 160 200 240 280 320 360 400 t (ns MB3889 level t (ns) (Continued) 31 ...

  • Page 32

    ... MB3889 (Continued ( (V) CTL ( (V) CTL Soft-start Operating Waveform (CH1 VIN 12 V CTL1 Open CTL2 “L”level CTL Soft-start Operating Waveform (CH2) ...

  • Page 33

    ... The worker must put on a grounding device containing 250 k • Do not apply a negative voltage. - Applying a negative voltage of 0 less to an LSI may generate a parasitic transistor, resulting in malfunction. ORDERING INFORMATION Part number MB3889PFT resistors in series. Package 30-pin plastic TSSOP (FPT-30P-M04) MB3889 Remarks 33 ...

  • Page 34

    ... MB3889 PACKAGE DIMENSION 30-pin plastic TSSOP (FPT-30P-M04) 7.80±0.10(.307±.004) INDEX 0.50(.020) 0.10(.004) 0.10(.004) 7.00(.276) 2001 FUJITSU LIMITED F30007SC-1 "A" +0.20 4.40 6.40±0.10 –0.10 (.252±.004) +.008 .173 –.004 0.20±0.03 0.127±0.03 (.008±.001) (.005±.001) 0.3865(.0152) 0.90± ...

  • Page 35

    ... MB3889 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, ...