MPQ8616-12 Datasheet, PDF (26/29 Pages) Monolithic Power Systems – High Efficiency, 6A/12A, 6V Synchronous Step-Down Converter

MPQ8616, 6A/12A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
inductor will have a larger physical size, higher
series resistance, and/or lower saturation current.
A good rule for determining the inductor value is
to allow the peak-to-peak ripple current in the
inductor to be approximately 10~30% of the
maximum output current. Also, make sure that
the peak inductor current is below the current
limit of the device. The inductance value can be
calculated as:
L  ^VOUT  (1 ^VOUT )
f_SW  I_L
V_IN
(25)
Where ΔI_L is the peak-to-peak inductor ripple
current.
Choose an inductor that will not saturate under
the maximum inductor peak current. The peak
inductor current can be calculated as:
I_LP
 I_OUT

V_{OUT  (1}
2  f_SW  L
V_{OUT )}
V_IN
(26)
The inductors listed in Table 1 are highly
recommended for the high efficiency they can
provide.
Table 1—Inductor Selection Guide
Part Number
FDU1250C-R50M
FDU1250C-R56M
FDU1250C-R75M
FDU1250C-1R0M
Manufacturer
TOKO
TOKO
TOKO
TOKO
Inductance
(µH)
0.50
0.56
0.75
1.0
DCR
(mΩ)
1.3
1.6
1.7
2.2
Current
Rating (A)
46.3
42.6
32.7
31.3
Dimensions
L x W x H (mm³)
13.3 x 12.1 x5
13.3 x 12.1 x5
13.3 x 12.1 x5
13.3 x 12.1 x5
Switching
Frequency
(kHz)
1000
800-1000
600-800
600
Typical Design Parameter Tables
The following tables include recommended
component values for typical output voltages
(1.0V, 1.2V, 1.8V, 3.3V) and switching
frequencies (600kHz, 800kHz, and 1MHz). Refer
to Tables 2-4 for design cases without external
ramp compensation and Tables 5-6 for design
cases with external ramp compensation.
External ramp is not needed when high-ESR
capacitors, such as electrolytic or POSCAPs are
used. External ramp is needed when low-ESR
capacitors, such as ceramic capacitors are used.
For cases not listed in this datasheet, a calculator
in excel spreadsheet can also be requested
through a local sales representative to assist with
the calculation.
Table 2—C_OUT-Poscap, 600kHz, 5V_IN
V_OUT
L
R1
R2
R7
(V) (μH) (kΩ)
(kΩ)
(kΩ)
1.0
1.0
19.8
30
300
1.2
1.0
29.4
30
365
1.5
1.0
29.4
20
453
1.8
1.0
39.2
20
549
3.3
1.0
44.2
10
1000
Table 3—C_OUT-Poscap, 800kHz, 5VIN
V_OUT
L
R1
R2
R7
(V) (μH) (kΩ)
(kΩ)
(kΩ)
1.0 0.75
20
30
210
1.2 0.75
20
20
270
1.5 0.75
30
20
330
1.8 0.75
39
20
499
3.3 0.75 44.2
10
750
Table 5—C_OUT-Ceramic, 600kHz, 5VIN
V_OUT
L
R1 R2 R4 C4 R7
(V) (μH) (kΩ) (kΩ) (kΩ) (pF) (kΩ)
1.0 1.0
21
30 240 470 309
1.2 1.0
33
30 220 470 365
1.5 1.0
51
30 330 390 464
1.8 1.0
45
20 270 470 549
3.3 1.0
62
10 160 680 953
Table 6—C_OUT-Ceramic, 800kHz, 5VIN
V_OUT
L
R1 R2 R4 C4 R7
(V) (μH) (kΩ) (kΩ) (kΩ) (pF) (kΩ)
1.0 0.75 21
30 200 470 226
1.2 0.75 34
30 200 470 270
1.5 0.75 34
20 220 470 324
1.8 0.75 47.5 20 225 470 402
3.3 0.75 57.6 10 200 560 750
MPQ8616 Rev. 1.01
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26
8/4/2013
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