LTC3812-5_15 Datasheet, PDF (29/34 Pages) Linear Technology – 60V Current Mode Synchronous Switching Regulator Controller

LTC3812-5
APPLICATIONS INFORMATION
• Use compact plane for switch node (SW) to improve
cooling of the MOSFETs and to keep EMI down.
• Use planes for V_IN and V_OUT to maintain good voltage
filtering and to keep power losses low.
• Flood all unused areas on all layers with copper. Flooding
with copper will reduce the temperature rise of power
component. You can connect the copper areas to any
DC net (V_IN, V_OUT, GND or to any other DC rail in your
system).
When laying out a printed circuit board, without a ground
plane, use the following checklist to ensure proper opera-
tion of the controller.
• Segregate the signal and power grounds. All small
signal components should return to the SGND pin at
one point which is then tied to the PGND pin close to
the source of M2.
• Place M2 as close to the controller as possible, keeping
the PGND, BG and SW traces short.
• Connect the input capacitor(s) C_IN close to the pow-
er MOSFETs. This capacitor carries the MOSFET AC
current.
• Keep the high dV/dt SW, BOOST and TG nodes away
from sensitive small-signal nodes.
• Connect the INTV_CC decoupling capacitor C_VCC closely
to the INTV_CC and SGND pins.
• Connect the top driver boost capacitor C_B closely to
the BOOST and SW pins.
• Connect the bottom driver decoupling capacitor C_INTVCC
closely to the INTV_CC and PGND pins.
PGOOD
R_ON
110k
C_ON
150k _100pF
100k
C_SS
1000pF
C_C2
47pF
R_C
C_C1
5pF
R_FB2 200k
1.89k
1 _ION
16
BOOST
2
LTC3812-5
V_RNG
15
TG
3
PGOOD
4 _FCB
5
6
I_TH
V_FB
SW ¹⁴
13
PGND
12
BG
7
11
RUN/SS
INTV_CC
8
SGND
10
EXTV_CC
9
NDRV
SGND
R_FB1
10k
R_NDRV
100k
M3
ZXMN10A07F
D_B
BAS19
C_IN1
68μF
100V
V_IN
12V TO 60V
C_IN2
1μF
100V
PGND
C_B
0.1μF
M1
L1
Si7850DP 7.7μH
C_DRVCC
0.1μF
C_VCC
1μF
M2
Si7850DP
D1
B1100
PGND
C_OUT1
270μF
6.3V
V_OUT
5V
6A
C_OUT2
10μF
6.3V
38125 F15
Figure 15. 12V to 60V Input Voltage to 5V/6A
38125fc
29