Reference Design of the MAX5073 Dual-Channel Step-Down Converter Operating at 2MHz Switching Frequency-EEWORLD

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This article presents a detailed reference design using the MAX5073 dual-channel step-down converter operating at a switching frequency of 2MHz. This design can be used in applications where board space is limited, as the higher switching frequency allows for smaller passive components. In addition, this power solution can be used in automotive electronics (with load dump protection), i.e., products that require switching frequencies outside the AM frequency modulation band. For example, automotive instrument clusters and infotainment systems.

The key specifications of the reference design are listed below, along with a detailed schematic (Figure 1) and bill of materials (Table 1) required for the application.

Specification

Input voltage: 5.5V to 16V
Converter 1 output voltage = 3.3V/2A (max)
Converter 2 output voltage = 2.5V/1A (max)
Switching frequency of each converter (fSW) = 2MHz
Ambient Temperature (TA) = -40°C to +85°C

Details Schematic (PDF)
Figure 1. MAX5073 Reference Design

Table 1. Bill of Materials

Designator	Value	Description	Part	Footprint	Manufacturer	Quantity
C1	100µF/35V	Capacitor	EEVFK1V101P	8mm x 10.2mm	Panasonic	1
C2, C3, C4, C17, C18	0.1µF/25V	Capacitors	GRM188R71E104KA01D	603	Murata	5
C5, C6, C7	22µF/6.3V	Capacitors	GRM31CR60J226KE19	1206	Murata	2
C8, C9	10µF/25V	Capacitors	GRM31CR61E106KA12	1206	Murata	1
C10, C12	2.2nF	Capacitors	GRM188R71H222JA01	603	Murata	2
C11	560pF	Capacitor	GRM188R71H561KA01	603	Murata	1
C13, C14	22pF	Capacitors	GRM1885C1H220JA01	603	Murata	2
C15	1nF	Capacitor	GRM18871H102KA01	603	Murata	1
C16	4.7µF/6.3V	Capacitor	GRM188R60J475KE19B	603	Murata	1
C19	0.22µF/10V	Capacitor	GRM188R71A224KA01	603	Murata	1
C20	0.01µF	Capacitor	GRM188R71H103KA01J	603	Murata	1
D1, D2	30V, 500mA	Schottky diodes	MBR0530	SOD123	ON Semiconductor	2
D3	40V, 3A	Schottky diode	MBRS340	SMC	ON Semiconductor	1
D4	40V, 2A	Schottky diode	MBRS240	SMB	ON Semiconductor	1
L1, L2	4.7µH	Inductors	IHLP2525-CZ	6.86mm x 6.47mm x 3.18mm	Vishay	1
R1, R11	100kΩ	Resistors	SMD, 1%, 0.125W	603	Vishay	2
R2	6.8Ω	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R3	4.7Ω	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R4, R8, R10	1.18kΩ	Resistors	SMD, 1%, 0.125W	603	Vishay	3
R5, R9	27.4kΩ	Resistors	SMD, 1%, 0.125W	603	Vishay	2
R6	10kΩ	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R7	12.7 kΩ	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R12	2.2Ω	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R13	6.19kΩ	Resistor	SMD, 1%, 0.125W	603	Vishay	1
R14	8.76kΩ	Resistor	SMD, 1%, 0.125W	603	Vishay	1
U1	MAX5073	Dual buck converter	MAX5073ETI+	32-TQFN_EP (5mm x 5mm)	Maxim	1

The data obtained from the actual measurement circuit gives the efficiency indicators of the device. For details, see Table 2 and Table 3.

Table 2. Efficiency indicators when VOUT2 is disabled
fSW = 2MHz, LOUT = 4.7µH, COUT = 22µF/6.3V (ceramic capacitor )

VIN (V)	IIN (A)	VOUT1 (V)	IOUT1 (A)	Efficiency (%)
14.007	0.065732	3.3371	0.1018	36.8973371
14.010	0.183690	3.3339	0.5122	66.3542117
14.005	0.267750	3.3321	0.8032	71.3722082
14.007	0.329490	3.3309	1.0112	72.9812485
14.005	0.449290	3.3298	1.4007	74.1230723
14.002	0.584520	3.3281	1.8203	74.0201375
14.001	0.650260	3.3267	2.0150	73.6279304

Table 3. Efficiency Specifications with VOUT1 Disabled
fSW = 2MHz, LOUT = 4.7µH, COUT = 22µF/6.3V (Ceramic Capacitor)

VIN (V)	IIN (A)	VOUT2 (V)	IOUT2 (A)	Efficiency (%)
14.008	0.044533	2.5350	0.1075	43.6845979
14.008	0.067144	2.5337	0.2049	55.1967881
14.003	0.087638	2.5337	0.3010	62.1452787
14.004	0.109076	2.5337	0.4003	66.3986847
14.005	0.133680	2.5337	0.5122	69.3178710
14.005	0.155350	2.5338	0.6097	71.0058542
14.008	0.255976	2.5334	1.0001	70.6597037