LTC3770_15 Datasheet, PDF (22/24 Pages) Linear Technology – Fast No RSENSE Step-Down Synchronous Controller with Margining, Tracking and PLL

LTC3770
APPLICATIONS INFORMATION
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 power
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 CV_CC closely
to the INTV_CC and PGND pins.
• Connect the top driver boost capacitor CB closely to
the BOOST and SW pins.
• Connect the V_IN pin decoupling capacitor C_IN closely
to the V_IN and PGND pins.
TYPICAL APPLICATIONS
1.8V/5A at 450kHz with Tracking
R_PG
100k
PGOOD
RUN
C_F
220pF
FCB
R7
47k
32 31 30 29 28 27 26 25
R_RUN
R8
51k
51k
PGOOD V_ON RUN FCB Z0 BOOST TG SW
R2 R_C
60.4k 10k
R1
CC2
30.1k 100pF
1 _VRNG
2 _VFB
3 _ITH
4
SGND
5
MARGIN1
MARGIN1
6
MARGIN0
MARGIN0
7
I_ON
R_ON
75k
8
V_REFIN
LTC3770EUH
SENSE+ ²⁴
SENSE– ²³
PGND ²²
BG ²¹
DRV_CC ²⁰
INTV_CC ¹⁹
18
Z2
Z1 ¹⁷
CC1
1000pF
R5
10k
V_REFOUT MPGM TRACK/SS PLLFLTR PLLIN V_IN V_INSNS ZV_IN
9
10
11
12
13 14 15 16
TRACK/SS
R6
V_CC
200k
5V
C_IN: TDK C4532X5R1H685M
C_OUT: PANASONIC EEFUE0G181R
L1: BI TECH 1.8μH HM65-H1R8-TB
M1, M2: PHILIPS PH3230
M1
PH3230
V_IN
4V TO 28V
1000pF
CB
0.22μF
L1
1.8μH
V_OUT
1.8V
5A
DB
D1
CMDSH-3 B340A
M2
PH3230
INTV_CC
CV_CC
4.7μF
+ ^COUT
180μF
4V
x2
C_OUT3
22μF
X5R
x2
C_IN
6.8μF
50V
x3
3770 TA02a
3770fc
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