MAX1887 Maxim Integrated Products, MAX1887 Datasheet - Page 29

• Manufacturer Part Number: MAX1887
• Description: (MAX1887 / MAX1897) Quick-PWM Slave Controllers
• Manufacturer: Maxim Integrated Products

5) Connect the output power planes (V
V
ground plane where sensitive analog components,
the master’s GND pin and V
go; and the slave’s analog ground plane where the
slave’s GND pin, and V
The master’s GND plane must meet the PGND
plane only at a single point directly beneath the IC.
Similarly, the slave’s GND plane must meet the
PGND plane only at a single point directly beneath
the IC. The respective master and slave ground
planes should connect to the high-power output
ground with a short metal trace from PGND to the
source of the low-side MOSFET (the middle of the
star ground). This point must also be very close to
the output capacitor ground terminal.
tem ground planes) directly to the output filter
capacitor positive and negative terminals with multi-
ple vias. Place the entire DC-DC converter circuit
as close to the CPU as is practical.
DD
bypass capacitor go; the master’s analog
(MASTER)
(MASTER)
( )* MAX1897 PINS ONLY
REF
______________________________________________________________________________________
(MASTER)
(300kHz)
FB
FLOAT
ILIM
CC
bypass capacitor go.
CC
Quick-PWM Slave Controllers for
bypass capacitor
Multiphase, Step-Down Supplies
CORE
V
(V
(POL)*
SHDN
ILIM
(TON)*
LIMIT
COMP
GND
DD
CC
)*
(MAX1897)*
and sys-
MAX1887
PGND
CM+
TRIG
CM-
CS+
BST
CS-
DH
V+
LX
DL
TRANSISTOR COUNT: 1422
PROCESS: BiCMOS
Pin Configurations (continued)
TOP VIEW
COMP
TRIG
CM+
ILIM
CM-
GND
CS+
CS-
Typical Operating Circuit
MASTER LOW-SIDE GATE DRIVER
5V BIAS
SUPPLY
MASTER CURRENT
SENSE RESISTOR
1
2
6
3
4
5
7
8
MAX1887
QSOP
INPUT
Chip Information
16
15
14
13
12
11
10
9
LIMIT
V+
BST
LX
DH
V
DL
PGND
DD
OUTPUT
29