General Description
The MAX1980 step-down slave controller is intended for
low-voltage, high-current, multiphase DC-DC applica-
tions. The MAX1980 slave controller can be combined
with any of Maxim’s Quick-PWM
step-down controllers
to form a multiphase DC-DC converter. Existing Quick-
PWM controllers, such as the MAX1718, function as the
master controller, providing accurate output-voltage regu-
lation, fast transient response, and fault protection fea-
tures. Synchronized to the master’s low-side gate driver,
the MAX1980 includes the Quick-PWM constant on-time
controller, gate drivers for a synchronous rectifier, active
current balancing, and precision current-limit circuitry.
The MAX1980 provides the same high-efficiency, ultra-
low duty factor capability, and excellent transient
response as other Quick-PWM controllers. The MAX1980
differentially senses the inductor currents of both the
master and the slave across current-sense resistors.
These differential inputs and the adjustable current-limit
threshold derived from an external reference allow the
slave controller to accurately balance the inductor cur-
rents and provide precise current-limit protection. The
MAX1980’s dual-purpose current-limit input also allows
the slave controller to automatically enter a low-power
standby mode when the master controller shuts down.
The MAX1980 features a driver-disable mode that forces
both gate drivers (DL and DH) low. While the MAX1980’s
drivers are disabled, the master controller can operate in
low-power skip mode, improving light-load efficiency.
Additionally, the MAX1980 includes selectable trigger
polarity, allowing the slave controller to trigger on the ris-
ing (out-of-phase) or falling (in-phase) edge of the mas-
ter’s low-side gate driver. Out-of-phase operation
staggers the master and slave’s on-times, reducing the
input ripple current and consequently the number of
input capacitors. The MAX1980 also features a selec-
table 200kHz/300kHz/550kHz switching frequency. The
MAX1980 is available in compact 20-pin 5mm
5mm
QFN and thin QFN packages.
Applications
Notebook Computers
CPU Core Supply
Single-Stage (BATT to V
CORE
) Converters
Two-Stage (5V to V
CORE
) Converters
Servers/Desktop Computers
Features
o
Quick-PWM Slave Controller
o
Precise, Active Current Balance (±1.25mV )
o
Driver Disable Improves Light Load Efficiency
o
Accurate, Adjustable Current-Limit Threshold
o
Optimized for Low-Output Voltages (
≤
2V)
o
4V to 28V Battery Input Range
o
Selectable 200kHz/300kHz/550kHz Switching
Frequency
o
Drive Large Synchronous-Rectifier MOSFETs
o
525μA (typ) I
CC
Supply Current
o
20μA Standby Supply Current
o
Compact 20-Pin 5mm
5mm QFN and Thin QFN
Packages
M
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
20
19
18
17
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
QFN/THIN QFN
5mm x 5mm
TOP VIEW
MAX1980
LX
CM+
CM-
TON
CS-
CS+
DH
V
CC
V
DD
DD
D
P
G
P
C
T
I
L
V
B
Pin Configuration
19-2298; Rev 2; 9/02
Ordering Information
PART
TEMP RANGE
-40
°
C to +100
°
C
PIN-PACKAGE
20 QFN (5mm x 5mm)
MAX1980EGP*
MAX1980ETP
-40
°
C to +100
°
C
20 Thin QFN
(5mm x 5mm)
Typical Operating Circuit appears at end of data sheet.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
*
Contact factory for availability.