LTC3810-5 Datasheet, PDF (32/36 Pages) Linear Technology – 60V Current Mode Synchronous Switching Regulator Controller

LTC3810-5
APPLICATIONS INFORMATION
C_IN is chosen for an RMS current rating of about 3A at
85°C. The output capacitors are chosen for a low ESR
of 0.018Ω to minimize output voltage changes due to
inductor ripple current and load steps. The ripple voltage
will be only:
ΔV_OUT(RIPPLE) = ΔI_L(MAX) • ESR = 2.4A • 0.018Ω
= 43mV
However, a 0A to 6A load step will cause an output change
of up to:
ΔV_OUT(STEP) = ΔI_LOAD • ESR = 6A • 0.018Ω
= 108mV
An optional 10μF ceramic output capacitor is included
to minimize the effect of ESL in the output ripple. The
complete circuit is shown in Figure 19.
PC Board Layout Checklist
When laying out a PC board follow one of two suggested
approaches. The simple PC board layout requires a dedi-
cated ground plane layer. Also, for higher currents, it is
recommended to use a multilayer board to help with heat
sinking power components.
• The ground plane layer should not have any traces and
it should be as close as possible to the layer with power
MOSFETs.
• Place C_IN, C_OUT, MOSFETs, D1 and inductor all in one
compact area. It may help to have some components
on the bottom side of the board.
• Use an immediate via to connect the components to
ground plane including SGND and PGND of LTC3810-5.
Use several bigger vias for power components.
R_ON
110k
PGOOD
250kHz
CLOCK
SHDN
C_ON
100pF
40.2k
60.4k
R_UV1
200k
0.01μF
10k
C_SS
1000pF
R_UV2
C_C2
14.3k
47pF
C_C1
R_FB2
R_C
200k
5pF
1.91k
LTC3810
31 _ION
BOOST ²⁷
2 _VON
3 _VRNG
4 _PGOOD
5 _{MODE_SYNC}
6 _ITH
7
8
V_FB
PLL/LPF
26
TG
SW ²⁵
SENSE^{+ 24}
SENSE^{– 20}
19
BGRTN
9
SS/TRACK
33
12
SGND
SHDN
13
UVIN
BG ¹⁸
17
DRV_CC
16
INTV_CC
EXTV_CC
15
14
NDRV
SGND
R_FB1
10k
R_NDRV
100k
M3
ZXMN10A07F
DB
BAS19
C_IN1
68μF
100V
C_B 0.1μF
M1
Si7852DP
V_IN
12V TO 60V
C_IN2
1μF
100V
PGND
C_DRVCC
0.1μF
C_VCC
1μF
L1
10μH
V_OUT
5V
6A
M2
Si7852DP
C_OUT1
270μF
6.3V
C_OUT2
10μF
D1
6.3V
B1100
C5
1μF
PGND
38105 F19
Figure 19. 12V to 60V Input Voltage to 5V/6A Synchronized at 250kHz
38105fc
32