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
TM
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 525A (typ) I
CC
Supply Current
o 20A Standby Supply Current
o Compact 20-Pin 5mm
5mm QFN and Thin QFN
Packages
MAX1980
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
________________________________________________________________ Maxim Integrated Products
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
DL
PGND
GND
POL
COMP
TRIG
ILIM
LIMIT
V+
BST
Pin Configuration
19-2298; Rev 2; 9/02
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.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX1980EGP*
-40C to +100C
20 QFN (5mm x 5mm)
MAX1980ETP
-40C to +100C
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.
MAX1980
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
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
= +70C)
20-Pin QFN (derate 20.0mW/C above +70C) .............1.60W
Operating Temperature Range .........................-40C to +100C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
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
= 0C to
+85C, unless otherwise noted. Typical values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PWM CONTROLLER
Battery voltage, V+
4.0
28
Input Voltage Range
V
CC
, V
DD
4.5
5.5
V
TON = GND
171
190
209
TON = open
320
355
390
On-Time (Note 1)
t
ON
V+ = 12V,
V
COMP
= 1.2V
TON = V
CC
464
515
566
ns
Trigger Delay (Note 2)
t
TRIG
75
ns
SUPPLY CURRENTS
Quiescent Supply Current (V+)
I+
Measured at V+; V
ILIM
> 0.35V
25
40
A
Quiescent Supply Current (V
DD
)
I
DD
Measured at V
DD
; V
ILIM
> 0.35V
<1
5
A
Quiescent Supply Current (V
CC
)
I
CC
Measured at V
CC
; V
ILIM
> 0.35V
525
800
A
Standby Supply Current (V+)
Measured at V+; ILIM = GND
<1
5
A
Standby Supply Current (V
DD
)
Measured at V
DD
; ILIM = GND
<1
5
A
Standby Supply Current (V
CC
)
Measured at V
CC
; ILIM = GND
20
40
A
D r i ver - D i sab l e S up p l y C ur r ent ( V + )
Measured at V+; DD = GND, V
ILIM
> 0.35V
25
40
A
Driver-Disable Supply Current
(V
DD
)
Measured at V
DD
; DD = GND, V
ILIM
> 0.35V
<1
5
A
Driver-Disable Supply Current
(V
CC
)
Measured at V
CC
; DD = GND, V
ILIM
> 0.35V
525
800
A
MAX1980
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
_______________________________________________________________________________________
3
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
= 0C to
+85C, unless otherwise noted. Typical values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CURRENT SENSING
On-Time Adjustment Range
0.42V < V
COMP
< 2.8V, V
OUT
0.7V
-40
+40
%
COMP Output Current
I
COMP
Sink and source
30
A
Current-Balance Offset
(V
CM+
- V
CM-
) - (V
CS+
- V
CS-
), I
COMP
= 0,
-100mV
(V
CM+
- V
CM-
)
+100mV
-1.25
+1.25
mV
Current-Balance
Transconductance
(V
CM+
- V
CM-
) - (V
CS+
- V
CS-
) = 25mV
1.2
mS
Current-Sense, Common-Mode
Range
CM+, CM-, CS+, CS-
-0.2
+2.0
V
Current-Sense Input Current
CM+, CM-, CS+, CS-
-1
1
A
V
ILIM
= 0.5V
47.5
50
52.5
Positive Current-Limit Threshold
V
C_LIM
V
CM+
- V
CM-
and
V
CS+
- V
CS-
V
ILIM
= 1V
97.5
100
102.5
mV
V
ILIM
= 0.5V
-80
-75
-70
Negative Current-Limit
Threshold
V
CS+
- V
CS-
V
ILIM
= 1V
-160
-150
-140
mV
ILIM Standby Threshold Voltage
0.2
0.3
V
ILIM Input Current
-100
100
nA
LIMIT Propagation Delay
t
LIMIT
Falling edge, 3mV over trip threshold
1.5
s
LIMIT Output Low Voltage
V
OL(LIMIT)
I
SINK
= 1mA
0.1
V
LIMIT Leakage Current
I
LIMIT
LIMIT forced to 5.5V
< 0.01
1
A
FAULT PROTECTION
V
CC
Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, switching
disabled below this level
3.45
3.85
V
Thermal-Shutdown Threshold
Rising, hysteresis = 15
C (typ)
160
C
GATE DRIVERS
DH Gate-Driver On-Resistance
(Note 3)
R
ON ( D H )
V
BST
- V
LX
forced to 5V
1.0
4.5
High state (pullup)
1.0
4.5
DL Gate-Driver On-Resistance
(Note 3)
R
ON(DL)
Low state (pulldown)
0.4
2.0
DH Gate-Driver Source/Sink
Current
I
DH
DH forced to 2.5V, V
BST
- V
LX
forced to 5V
1.3
A
DL Gate-Driver Sink Current
I
DL
DL forced to 2.5V
4.0
A
DL Gate-Driver Source Current
I
DL
DL forced to 2.5V
1.3
A
DL rising
35
Dead Time
DH rising
26
ns
DD falling (Note 4)
225
1000
Driver Disable Delay
t
DD
DD rising (Note 4)
65
1000
ns
MAX1980
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
4
_______________________________________________________________________________________
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
= -40C
to +100C, unless otherwise noted.) (Note 5)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PWM CONTROLLER
TON = GND (550kHz)
171
209
TON = open (300kHz)
320
390
On Time (Note 1)
t
ON
V+ = 12V,
V
COMP
= 1.2V
TON = V
CC
(200kHz)
464
566
ns
SUPPLY CURRENTS
Quiescent Supply Current (V+)
I+
Measured at V+; V
ILIM
> 0.35V
40
A
Quiescent Supply Current (V
DD
)
I
DD
Measured at V
DD
; V
ILIM
> 0.35V,
T
A
= -40C to +85C
5
A
Quiescent Supply Current (V
CC
)
I
CC
Measured at V
CC
; V
ILIM
> 0.35V
800
A
Standby Supply Current (V+)
Measured at V+; ILIM = GND,
T
A
= -40C to +85C
5
A
Standby Supply Current (V
DD
)
Measured at V
DD
; ILIM = GND,
T
A
= -40C to +85C
5
A
Standby Supply Current (V
CC
)
Measured at V
CC
; ILIM = GND
40
A
Driver-Disable Supply Current
(V+)
Measured at V+; DD = GND, V
ILIM
> 0.35V
40
A
Driver-Disable Supply Current
(V
DD
)
Measured at V
DD
; DD = GND, V
ILIM
>
0.35V, T
A
= -40C to +85C
5
A
Driver-Disable Supply Current
(V
CC
)
Measured at V
CC
; DD = GND, V
ILIM
> 0.35V
800
A
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
= 0C to
+85C, unless otherwise noted. Typical values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC
High
2.4
POL Logic Levels
V
POL
V
CC
= 4.5V to 5.5V
Low
0.8
V
High
2.4
DD Logic Levels
V
DD
V
CC
= 4.5V to 5.5V
265mV hysteresis
Low
0.6
V
High
3.0
TRIG Logic Levels
V
TRIG
350mV hysteresis
Low
1.2
V
Logic high (V
CC
; 200kHz operation)
V
CC
- 0.4
Open (300kHz operation)
1.6
3.1
TON Logic Levels
V
TON
Logic low (GND; 550kHz operation)
0.5
V
TRIG
-1
+1
DD
-1
+1
POL
-2
+1
Logic Input Current
TON = GND or V
DD
-2
+3
A
MAX1980
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
_______________________________________________________________________________________
5
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
= -40C
to +100C, unless otherwise noted.) (Note 5)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CURRENT SENSING
On-Time Adjustment Range
0.42V < V
COMP
< 2.8V, V
OUT
0.7V
-40
+40
%
COMP Output Current
I
COMP
Sink and source
30
A
Current-Balance Offset
(V
CM+
- V
CM-
) - (V
CS+
- V
CS-
), I
COMP
= 0,
-100mV
(V
CM+
- V
CM-
)
+100mV
-2.0
+2.0
mV
Current-Sense, Common-Mode
Range
CM+, CM-, CS+, CS-
-0.2
+2.0
V
V
ILIM
= 0.5V
47.5
52.5
Positive Current-Limit Threshold
V
C_LIM
V
CM+
- V
CM-
and
V
CS+
- V
CS-
V
ILIM
= 1V
97
103
mV
V
ILIM
= 0.5V
-80
-70
Negative Current-Limit
Threshold
V
CS+
- V
CS-
V
ILIM
= 1V
-160
-140
mV
ILIM Standby Threshold Voltage
0.2
0.3
V
FAULT PROTECTION
V
CC
Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, switching
disabled below this level
3.45
3.90
V
GATE DRIVERS
DH Gate-Driver On-Resistance
(Note 3)
R
ON ( D H )
V
BST
- V
LX
forced to 5V
4.5
High state (pullup)
4.5
DL Gate-Driver On-Resistance
(Note 3)
R
ON(DL)
Low state (pulldown)
2.0
LOGIC
High
3.0
TRIG Logic Levels
V
TRIG
350mV hysteresis
Low
1.2
V
Logic high (V
CC
; 200kHz operation)
V
CC
- 0.4
Open (300kHz operation)
1.6
3.1
TON Logic Levels
V
TON
Logic low (GND; 550kHz operation)
0.5
V
Note 1: On-time specifications are measured from 50% point to 50% point at the DH pin with LX = PGND, V
BST
= 5V, and a 500pF
capacitor from DH to LX to simulate external MOSFET gate capacitance. Actual in-circuit times may be different due to
MOSFET switching speeds.
Note 2: The trigger delay time, t
TRIG
, is measured from the time the TRIG pin transitions to the time when the DL pin goes low.
Note 3: Production testing limitations due to package handling require relaxed maximum on-resistance specifications for the QFN
package.
Note 4: The driver-disable delay time (t
DD
) is measured from the time the DD pin transitions to the time when the DL or DH pin tran-
sitions.
Note 5: Specifications to -40C and +100C are guaranteed by design and not production tested.
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