Multi-Phase MPQ2908A with Thermal Balancing
12V Output DC/DC Converter for 48V Batteries
DOWNLOAD THE FULL REFERENCE DESIGN

Get valuable resources straight to your inbox - sent out once per month
We value your privacy
1 Overview
1.1 Description
New automotive designs are adopting 48V power systems to reduce the weight and power loss in the vehicle’s cable harnesses. Moreover, when the system must withstand high loads, the required power increases, which means it is vital to use power converter topologies with higher deliverable power, such as an interleaved topology. When using this topology, it is usually required to optimize thermal distribution to equalize the MOSFETs’ degradation and avoid overheating parts of the board. An excellent layout can help with these thermal constraints, as well as promoting good current sharing between both controllers by equally distributing the load current between all converters. Passing the same current through both phases, as well as creating a symmetrical layout, helps the MOSFETs experience an equal temperature rise, which means they will degrade at a similar speed.
This reference design showcases a 48V to 12V interleaved converter that can supply up to 20A of output load. To improve current sharing between both controllers, a thermal balancing circuit is implemented, and a frequency spread spectrum (FSS) modulator is added to reduce EMC.
1.2 Features
- Wide 4V to 60V Operating Input Range
- Dual N-Channel MOSFET Driver Phases
- 0.8V Reference Voltage with ±1.5% Accuracy for
Over-Temperature Conditions - Low-Dropout Operation: Maximum Duty Cycle at 99.5%
- 100kHz to 1000kHz Configurable Frequency
- 180° Out-of-Phase SYNCO Pin
- Configurable Soft Start (SS)
- Power Good (PG) Output Voltage (VOUT) Monitoring
- Selectable Cycle-by-Cycle Current Limit
- Output Over-Voltage Protection (OVP)
- Over-Current Protection (OCP)
- External Reverse-Polarity Protection (RPP)
- External Input OVP
- Forced Continuous Conduction Mode (CCM)
- External Frequency Spread Spectrum (FSS) Modulation
- Enable Phase Thermal Balancing
- Available in TSSOP20-EP and QFN-20 (3mmx4mm) Packages
- Available in a Wettable Flank Package
- Available in AEC-Q100 Grade 1

Figure 1: EVQ2908A_48V_L_02A
1.3 Applications
- Automotive and Industrial Power Systems
2 Reference Design
2.1 Block Diagram
Figure 2 shows the reference design block diagram. The MPQ2908A is a buck converter with 48V nominal input, 12V/20A output capability, input EMI filter, reverse-polarity protection (RPP), over-voltage protection (OVP), two-phase interleaving, frequency spread spectrum (FSS) modulation, and phase thermal balancing.

Figure 2: Block Diagram
2.2 Related Solutions
This reference design is based on the following MPS solution(s):
Table 1: MPS Solutions
MPS Integrated Circuit | Description |
MPQ2908A | 4V to 60V input, current mode, synchronous step-down controller, AEC-Q100 qualified |
2.3 System Specifications
Table 2: System specifications
Parameter | Specification |
Input voltage (VIN) range | 24VDC to 60VDC |
Output voltage (VOUT) | 12VDC |
Maximum output current (IOUT) | 20A (with 12V output) |
Switching frequency (fSW) | 225kHz |
Board form factor | 150mmx100mm |
Peak efficiency | 95.83% (13A load, 48V input) |
12V output ripple | 22mVPP |
2.4 Schematic

Figure 3: Schematic (Page 1)

Figure 4: Schematic (Page 2)

Figure 5: Schematic (Page 3)

Figure 6: Schematic (Page 4)
2.5 BOM
Table 3: Bill of Materials
Qty | Ref | Value | Description | Package | Manufacturer | Manufacturer PN |
3 | C1, C33, C51 | 1µF, 100V | 10%, X7S, MLCC | 0805 | Murata | GCM21BC72A105KE36L |
1 | C2 | 22nF, 100V | 5%, X7R, MLCC | 1206 | Kemet | C1206C223J1RACTU |
3 | C3, C17, C18 | 2.2µF, 100V | 10%, X7S, MLCC | 1206 | Murata | GCM31CC72A225KE02L |
6 | C4, C5, C14, C25, C34, C52 | 100nF, 100V | 10%, X7R, MLCC | 0603 | Murata | GCJ188R72A104KA01D |
4 | C10, C11, C21, C22 | 10µF, 100V | 10%, X7S, MLCC | 2210 | TDK | CGA9N3X7S2A106K230KE |
2 | C15, C16 | 47µF, 80V | Aluminium electrolytic capacitor | 10mm x 10mm | Panasonic | EEE-FN1K470UV |
2 | C19, C20 | 4.7µF, 100V | 10%, X7S, MLCC | 1210 | Murata | GCM32DC72A475KE02L |
1 | C26 | 1µF, 16V | 10%, X7R, MLCC | 0603 | Murata | GCM188R71C105KA64J |
1 | C27 | 6.8nF, 16V | 10%, X7R, MLCC | 0603 | Vishay Vitramon | VJ0603Y682KXJCW1BC |
2 | C28, C29 | 100nF, 25V | 10%, X7R, MLCC | 0603 | Kemet | C0603C104K3RAC7013 |
1 | C31 | 47µF, 6.3V | 20%, X5R, MLCC | 0603 | Taiyo Yuden | JMK107BBJ476MA-RE |
2 | C35, C53 | 220nF, 16V | 10%, X7R, MLCC | 0603 | Kemet | C0603X224K4RACTU |
4 | C36, C38, C54, C56 | 4.7µF, 16V | 10%, X5R, MLCC | 0603 | TDK | C1608X5R1C475K080AC |
4 | C37, C44, C45, C46 | 22µF 25V | 10%, X5R, MLCC | 1210 | Kemet | C1210C226K3PACTU |
2 | C42, C58 | 10nF, 16V | 5%, X7R, MLCC | 0603 | Kemet | C0603C103J4RACTU |
1 | C43 | 4.7nF, 16V | 10%, X7R, MLCC | 0603 | Kemet | C0603C472K4RACTU |
2 | C47, C48 | 100µF, 25V | Aluminium electrolytic capacitors | 10mm x 10mm | Panasonic | EEE-FN1E101UV |
6 | D1, D3, D4, D5, D7, D9 | 200V, 0.25A | General-purpose diode, VBREAK = 200V | SOD-323 | Nexperia | BAS321,115 |
1 | D2 | 10V, 5mA | Zener diode | SOD-523 | On Semiconductor | SZMM5Z10VT5G |
1 | D6 | 65V, 50nA | Zener diode | SOT-23 | On Semiconductor | SZBZX84C62LT1G |
2 | D8, D10 | 150V, 1A | Schottky rectifier diode | SOD-123FL | Rohm | RB168MM150TFTR |
4 | J1, J2, J3, J4 | M3, 50A | M3 through-hole terminal | 7mm x 7mm | Wurth | 74650073R |
2 | L2, L3 | 2.2µH, 8A | Fixed inductor | 7030 | Eaton Bussmann | HCMA0703-2R2-R |
2 | L6, L7 | 6.8µH, 11.6A | Fixed inductor | 13mm x 12.5mm | TDK | SPM12565VT-6R8M-D |
2 | Q1, Q2 | 80V | N-channel MOSFET, ID = 123A, VDSBREAK = 80V | SOIC-8 | On Semiconductor | NVMFS6H818NT1G |
1 | Q3 | NPN | NPN BJT | SOT-23-3 | Nexperia | BC846215 |
4 | Q4, Q5, Q6, Q7 | 80V | N-channel MOSFET, ID = 60A, VDSBREAK = 80V | SO-8L | Vishay Siliconix | SQJA82EP-T1_GE3 |
8 | R1, R6, R12, R13, R15, R16, R21, R26 | 1kΩ, 5% | Thick film resistor | 0603 | Yageo | RC0603JR-131KL |
1 | R2 | 1mΩ, 2% | Current-sense resistor | 1530 | Ohmite | FC4L76R001GER |
1 | R3 | 5.1kΩ, 1% | Thick film resistor | 0603 | Yageo | RC0603FR-075K1L |
4 | R4, R39, R43, R61 | 100kΩ, 5% | Thick film resistor | 0603 | Vishay | CRCW0603100KFKEBC |
2 | R5, R7 | 20kΩ, 1% | Thick film resistor | 0603 | Yageo | RC0603FR-1320KL |
1 | R19 | 1MΩ, 1% | Thick film resistor | 0603 | Yageo | RC0603FR-071ML |
2 | R20, R35 | 10kΩ, 1% | Thick film resistor | 0603 | Rohm | ESR03EZPF1002 |
1 | R28 | 11kΩ, 5% | Thick film resistor | 0603 | Panasonic | ERJ-3GEYJ113V |
2 | R29, R30 | 10kΩ, 0.5% | NTC thermistor | 0603 | TDK | NTCG163JX103DTDS |
1 | R31 | 510kΩ, 1% | Thick film resistor | 0603 | Yageo | AC0603FR-07510KL |
19 | R32, R36, R38, R40, R44, R46, R48, R49, R50, R52, R56, R58, R62, R63, R65, R67, R68, R74, R77 | 0Ω | Thick film resistor | 0603 | Vishay Dale | CRCW06030000Z0EAHP |
1 | R34 | 33kΩ, 1% | Thick film resistor | 0603 | Yageo | RC0603FR-0733KL |
1 | R41 | 5.6kΩ, 5% | Thick film resistor | 0603 | Vishay Dale | CRCW06035K60JNEB |
2 | R42, R60 | 4mΩ, 1% | Current-sense resistor | 2512 | Susumu | KRL6432E-C-R004-F-T1 |
2 | R47, R66 | 88.7kΩ, 1% | Thick film resistor | 0603 | Panasonic | ERJ-3EKF8872V |
1 | R51 | 10Ω, 5% | Thick film resistor | 0603 | Yageo | RC0603JR-0710RL |
1 | R53 | 169kΩ, 1% | Thick film resistor | 0603 | Panasonic | ERJ-3EKF1693V |
1 | R54 | 12kΩ, 1% | Thick film resistor | 0603 | Panasonic | ERJ-1GNF1202C |
1 | R57 | 8.66kΩ, 1% | Thick film resistor | 0603 | Panasonic | ERJ-3EKF8661V |
1 | U2 | 2V to 50V | 555 timer | SOIC-8 | TI | TLC555QDRQ1 |
1 | U3 | 150kHz, 130dB | Rail-to-rail operational amplifier | TSOT-23 | Analog Devices | LTC2054IS5#TRMPBF |
2 | U4, U5 | MPQ2908A | Buck switching power converter | QFN-20 (3mm x 4mm) | MPS | MPQ2908AGLE-AEC1 |
2.6 PCB Layout

Figure 7: Top Layer

Figure 8: Mid-Layer 1

Figure 9: Mid-Layer 2

Figure 10: Mid-Layer 3

Figure 11: Mid-Layer 4

Figure 12: Bottom Layer
直接登录
创建新帐号