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19-2298; Rev 2; 9/02
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
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.
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
Features
MAX1980
Ordering Information
PART
MAX1980EGP*
MAX1980ETP
TEMP RANGE
-40°C to +100°C
-40°C to +100°C
PIN-PACKAGE
20 QFN (5mm x 5mm)
20 Thin QFN
(5mm x 5mm)
*Contact
factory for availability.
Pin Configuration
BST
16
15
14
LX
DH
DD
V
CC
V
DD
13
12
11
6
COMP
7
POL
8
GND
9
PGND
10
DL
V+
17
TOP VIEW
20
CM+
CM-
TON
CS-
CS+
1
2
3
4
5
19
18
MAX1980
Applications
Notebook Computers
CPU Core Supply
Single-Stage (BATT to V
CORE
) Converters
Two-Stage (5V to V
CORE
) Converters
Servers/Desktop Computers
QFN/THIN QFN
5mm x 5mm
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit appears at end of data sheet.
1
________________________________________________________________
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.
LIMIT
TRIG
ILIM
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
MAX1980
ABSOLUTE MAXIMUM RATINGS
V+ to GND ..............................................................-0.3V to +30V
V
CC
, V
DD
to GND .....................................................-0.3V to +6V
PGND to GND.....................................................................±0.3V
TRIG, LIMIT to GND .................................................-0.3V to +6V
DD
to GND ...............................................................-0.3V to +6V
ILIM, CM+, CM-, CS+, CS-, COMP
to GND....................................................-0.3V to (V
CC
+ 0.3V)
TON, POL to GND ......................................-0.3V to (V
CC
+ 0.3V)
DL to PGND................................................-0.3V to (V
DD
+ 0.3V)
BST to GND ............................................................-0.3V to +36V
DH to LX ....................................................-0.3V to (V
BST
+ 0.3V)
LX to BST..................................................................-6V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
20-Pin QFN (derate 20.0mW/°C above +70°C) .............1.60W
Operating Temperature Range .........................-40°C to +100°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V+ = 15V, V
CC
= V
DD
= 5V, V
OUT
= V
COMP
= 1.2V, V
CM+
= V
CM-
= V
CS+
= V
CS-
= 1.2V,
DD
= V
CC
,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
PWM CONTROLLER
Input Voltage Range
Battery voltage, V+
V
CC
, V
DD
TON = GND
On-Time (Note 1)
Trigger Delay (Note 2)
SUPPLY CURRENTS
Quiescent Supply Current (V+)
Quiescent Supply Current (V
DD
)
Quiescent Supply Current (V
CC
)
Standby Supply Current (V+)
Standby Supply Current (V
DD
)
Standby Supply Current (V
CC
)
Driver-Disable Supply Current (V+)
Driver-Disable Supply Current
(V
DD
)
Driver-Disable Supply Current
(V
CC
)
I+
I
DD
I
CC
Measured at V+; V
ILIM
> 0.35V
Measured at V
DD
; V
ILIM
> 0.35V
Measured at V
CC
; V
ILIM
> 0.35V
Measured at V+; ILIM = GND
Measured at V
DD
; ILIM = GND
Measured at V
CC
; ILIM = GND
Measured at V+;
DD
= GND, V
ILIM
> 0.35V
Measured at V
DD
;
DD
= GND, V
ILIM
> 0.35V
Measured at V
CC
;
DD
= GND, V
ILIM
> 0.35V
25
<1
525
<1
<1
20
25
<1
525
40
5
800
5
5
40
40
5
800
µA
µA
µA
µA
µA
µA
µA
µA
µA
t
ON
t
TRIG
V+ = 12V,
V
COMP
= 1.2V
TON = open
TON = V
CC
4.0
4.5
171
320
464
190
355
515
75
28
5.5
209
390
566
ns
ns
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = 15V, V
CC
= V
DD
= 5V, V
OUT
= V
COMP
= 1.2V, V
CM+
= V
CM-
= V
CS+
= V
CS-
= 1.2V,
DD
= V
CC
,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CURRENT SENSING
On-Time Adjustment Range
COMP Output Current
Current-Balance Offset
Current-Balance
Transconductance
Current-Sense, Common-Mode
Range
Current-Sense Input Current
Positive Current-Limit Threshold
Negative Current-Limit
Threshold
ILIM Standby Threshold Voltage
ILIM Input Current
LIMIT Propagation Delay
LIMIT Output Low Voltage
LIMIT Leakage Current
FAULT PROTECTION
V
CC
Undervoltage Lockout
Threshold
Thermal-Shutdown Threshold
GATE DRIVERS
DH Gate-Driver On-Resistance
(Note 3)
DL Gate-Driver On-Resistance
(Note 3)
DH Gate-Driver Source/Sink
Current
DL Gate-Driver Sink Current
DL Gate-Driver Source Current
Dead Time
Driver Disable Delay
t
DD
R
ON(DH)
R
ON(DL)
I
DH
I
DL
I
DL
V
BST
- V
LX
forced to 5V
High state (pullup)
Low state (pulldown)
DH forced to 2.5V, V
BST
- V
LX
forced to 5V
DL forced to 2.5V
DL forced to 2.5V
DL rising
DH rising
DD
falling (Note 4)
DD
rising (Note 4)
1.0
1.0
0.4
1.3
4.0
1.3
35
26
225
65
1000
1000
4.5
4.5
2.0
Ω
Ω
A
A
A
ns
ns
Rising edge, hysteresis = 20mV, switching
disabled below this level
Rising, hysteresis = 15°C (typ)
3.45
160
3.85
V
°C
t
LIMIT
V
OL(LIMIT)
I
LIMIT
Falling edge, 3mV over trip threshold
I
SINK
= 1mA
LIMIT forced to 5.5V
< 0.01
V
C_LIM
I
COMP
0.42V < V
COMP
< 2.8V, V
OUT
≥
0.7V
Sink and source
(V
CM+
- V
CM-
) - (V
CS+
- V
CS-
), I
COMP
= 0,
-100mV
≤
(V
CM+
- V
CM-
)
≤
+100mV
(V
CM+
- V
CM-
) - (V
CS+
- V
CS-
) = ±25mV
CM+, CM-, CS+, CS-
CM+, CM-, CS+, CS-
V
CM+
- V
CM-
and
V
CS+
- V
CS-
V
CS+
- V
CS-
V
ILIM
= 0.5V
V
ILIM
= 1V
V
ILIM
= 0.5V
V
ILIM
= 1V
-0.2
-1
47.5
97.5
-80
-160
0.2
-100
1.5
0.1
1
50
100
-75
-150
-40
30
-1.25
1.2
+2.0
1
52.5
102.5
-70
-140
0.3
100
+1.25
+40
%
µA
mV
mS
V
µA
mV
mV
V
nA
µs
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1980
_______________________________________________________________________________________
3
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
MAX1980
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = 15V, V
CC
= V
DD
= 5V, V
OUT
= V
COMP
= 1.2V, V
CM+
= V
CM-
= V
CS+
= V
CS-
= 1.2V,
DD
= V
CC
,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
LOGIC
POL Logic Levels
DD
Logic Levels
TRIG Logic Levels
V
POL
V
DD
V
TRIG
V
CC
= 4.5V to 5.5V
V
CC
= 4.5V to 5.5V
265mV hysteresis
350mV hysteresis
High
Low
High
Low
High
Low
V
CC
- 0.4
1.6
-1
-1
-2
-2
3.1
0.5
+1
+1
+1
+3
µA
V
3.0
1.2
2.4
0.6
2.4
0.8
V
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Logic high (V
CC
; 200kHz operation)
TON Logic Levels
V
TON
Open (300kHz operation)
Logic low (GND; 550kHz operation)
TRIG
Logic Input Current
DD
POL
TON = GND or V
DD
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V+ = 15V, V
CC
= V
DD
= 5V, V
OUT
= V
COMP
= 1.2V, V
CM+
= V
CM-
= V
CS+
= V
CS-
= 1.2V,
DD
= V
CC
,
T
A
= -40°C
to +100°C,
unless otherwise noted.) (Note 5)
PARAMETER
PWM CONTROLLER
TON = GND (550kHz)
On Time (Note 1)
SUPPLY CURRENTS
Quiescent Supply Current (V+)
Quiescent Supply Current (V
DD
)
Quiescent Supply Current (V
CC
)
Standby Supply Current (V+)
Standby Supply Current (V
DD
)
Standby Supply Current (V
CC
)
Driver-Disable Supply Current
(V+)
Driver-Disable Supply Current
(V
DD
)
Driver-Disable Supply Current
(V
CC
)
I+
I
DD
I
CC
Measured at V+; V
ILIM
> 0.35V
Measured at V
DD
; V
ILIM
> 0.35V,
T
A
= -40°C to +85°C
Measured at V
CC
; V
ILIM
> 0.35V
Measured at V+; ILIM = GND,
T
A
= -40°C to +85°C
Measured at V
DD
; ILIM = GND,
T
A
= -40°C to +85°C
Measured at V
CC
; ILIM = GND
Measured at V+;
DD
= GND, V
ILIM
> 0.35V
Measured at V
DD
;
DD
= GND, V
ILIM
>
0.35V, T
A
= -40°C to +85°C
Measured at V
CC
;
DD
= GND, V
ILIM
> 0.35V
40
5
800
5
5
40
40
5
800
µA
µA
µA
µA
µA
µA
µA
µA
µA
t
ON
V+ = 12V,
V
COMP
= 1.2V
TON = open (300kHz)
TON = V
CC
(200kHz)
171
320
464
209
390
566
ns
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
4
_______________________________________________________________________________________