19-2861; Rev 3; 2/07
KIT
ATION
EVALU
BLE
AVAILA
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
General Description
The MAX1540A/MAX1541 dual pulse-width modulation
(PWM) controllers provide the high efficiency, excellent
transient response, and high DC-output accuracy nec-
essary for stepping down high-voltage batteries to gen-
erate low-voltage chipset and RAM power supplies in
notebook computers.
The Maxim proprietary Quick-PWM™ controllers are
free running, constant on-time with input feed forward.
This configuration provides ultra-fast transient
response, wide input-output (I/O) differential range, low
supply current, and tight load-regulation characteris-
tics. The controllers can accurately sense the inductor
current across an external current-sense resistor in
series with the output to ensure reliable overload and
inductor saturation protection. Alternatively, the con-
trollers can use the synchronous rectifier itself or loss-
less inductor current-sensing methods to provide
overload protection with lower power dissipation.
For a single step-down PWM controller with inductor-
saturation protection, external-reference input voltage,
and dynamically selectable output voltages, refer to the
MAX1992/MAX1993 data sheet.
Features
♦
Inductor-Saturation Protection
♦
Accurate Differential Current-Sense Inputs
♦
Dual Ultra-High-Efficiency Quick-PWMs with
100ns Load-Step Response
♦
MAX1540A
1.8V/1.2V Fixed or 0.7V to 5.5V Adjustable
Output (OUT1)
2.5V/1.5V Fixed or 0.7V to 5.5V Adjustable
Output (OUT2)
Fixed 5V, 100mA Linear Regulator
♦
MAX1541
External Reference Input (REFIN1)
Dynamically Selectable Output Voltage—0.7V
to 5.5V (OUT1)
2.5V/1.8V Fixed or 0.7V to 5.5V Adjustable
Output (OUT2)
Optional Power-Good and Fault Blanking
During Transitions
Fixed 5V or Adjustable 100mA Linear Regulator
♦
1% V
OUT
Accuracy over Line and Load
♦
2V to 28V Battery Input Range
♦
170kHz to 620kHz Selectable Switching
Frequency
♦
Overvoltage/Undervoltage-Protection Option
♦
1.7ms Digital Soft-Start
♦
Drives Large Synchronous-Rectifier FETs
♦
2V ±0.7% Reference Output
♦
Separate Power-Good Window Comparators
MAX1540A/MAX1541
Applications
Notebook Computers
Core/I/O Supplies as Low as 0.7V
0.7V to 5.5V Supply Rails
CPU/Chipset/GPU with Dynamic Voltage Core
Supplies (MAX1541)
DDR Memory Termination (MAX1541)
Active Termination Buses (MAX1541)
Pin Configurations
LDOOUT
LDOON
BST1
V+
TOP VIEW
24
23
22
21
20
19
18
Ordering Information
DH1
17
GND
DL1
DL2
LX1
25
26
27
28
29
30
31
32
16
15
14
13
BST2
LX2
DH2
PART
MAX1540AETJ
MAX1540AETJ+
MAX1541ETL
MAX1541ETL+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
32 Thin QFN
5mm x 5mm
32 Thin QFN
5mm x 5mm
40 Thin QFN
6mm x 6mm
40 Thin QFN
6mm x 6mm
PKG
CODE
T3255-4
T3255-4
T4066-5
PGOOD1
OUT1
FB1
CSN1
CSP1
PGOOD2
OUT2
FB2
MAX1540A
12
11
10
9
ON2
ON1
CSN2
CSP2
1
2
3
4
5
6
7
ILIM2
OVP/UVP
ILIM1
SKIP
LSAT
TON
T4066-5
+Denotes
a lead-free package.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
THIN QFN
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
V
CC
REF
8
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
MAX1540A/MAX1541
ABSOLUTE MAXIMUM RATINGS
V+, LDOON to GND ...............................................-0.3V to +28V
LDOOUT to GND (MAX1540A, Note 1)....................-0.3V to +6V
LDOOUT to GND (MAX1541, Note 1) ....................-0.3V to +28V
V
DD
to GND (MAX1541, Note 1) ..............................-0.3V to +6V
V
CC
, ON_ to GND.....................................................-0.3V to +6V
SKIP,
PGOOD_ to GND............................................-0.3V to +6V
FB_, CSP_, ILIM_ to GND.........................................-0.3V to +6V
TON, OVP/UVP, LSAT to GND ...................-0.3V to (V
CC
+ 0.3V)
REF, OUT_ to GND.....................................-0.3V to (V
CC
+ 0.3V)
LDOIN to GND (MAX1541).....................................-0.3V to +28V
REFIN1, GATE, OD, FBLDO to GND (MAX1541).....-0.3V to +6V
FBLANK, CC1 to GND (MAX1541).............-0.3V to (V
CC
+ 0.3V)
DL_ to GND (Note 1) ..................................-0.3V to (V
DD
+ 0.3V)
CSN_ to GND ............................................................-2V to +30V
DH_ to LX_..................................................-0.3V to (BST + 0.3V)
LX_ to GND................................................................-2V to +30V
BST_ to LX_ ..............................................................-0.3V to +6V
REF Short Circuit to GND ...........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
32-Pin 5mm x 5mm Thin QFN (derated 21.3mW/°C
above +70°C).............................................................1702mW
40-Pin 6mm x 6mm Thin QFN (derated 26.3mW/°C
above +70°C).............................................................2105mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
For the MAX1540A, the gate-driver input supply (V
DD
) is internally connected to the fixed 5V linear-regulator output
(LDOOUT), and the linear-regulator input supply (LDOIN) is internally connected to the battery voltage input (V+).
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
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V,
SKIP
= GND, LDOIN (MAX1541) = V+,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
INPUT SUPPLIES (Note 1)
V
IN
Input Voltage Range
V
BIAS
V
LDOIN
MAX1540A: battery voltage, V+ > V
LDOOUT
MAX1541: battery voltage, V+ > V
LDOOUT
V
CC,
V
DD
(MAX1541)
MAX1541: LDO input supply,
V
LDOIN
> V
LDOOUT
FB1 and FB2 forced above the regulation
point, LSAT = GND
Quiescent Supply Current (V
CC
)
I
CC
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
, V
LSAT
> 0.5V
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
MAX1540A: FB1 and FB2 forced above the
regulation point, ON1 or ON2 = V
CC
,
V
LDOON
= V+ = 28V
MAX1541: ON1 or ON2 = V
CC
,
V
LDOON
= V+ = 28V
Quiescent Supply Current
(LDOIN, MAX1541 Only)
Standby Supply Current (V
CC
)
I
LDOIN
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
,
V
LDOON
= V+ = 28V
ON1 = ON2 = GND, V
LDOON
= V+ = 28V
<1
25
<1
5.5
2
4.5
4.5
0.7
28
28
5.5
28
1.5
mA
1.8
5
µA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Quiescent Supply Current
(V
DD
, MAX1541 Only)
I
DD
150
µA
40
Quiescent Supply Current (V+)
I
V+
110
5
µA
µA
2
_______________________________________________________________________________________
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
MAX1540A/MAX1541
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V,
SKIP
= GND, LDOIN (MAX1541) = V+,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
Standby Supply Current
(V
DD
, MAX1541 Only)
SYMBOL
CONDITIONS
ON1 = ON2 = GND, V
LDOON
= V+ = 28V
MAX1540A: ON1 = ON2 = GND,
LDOON = V+ = 28V, V
CC
= 0 or 5V
MAX1541: ON1 = ON2 = GND,
LDOON = V+ = 28V, V
CC
= V
DD
= 0 or 5V
Standby Supply Current
(LDOIN, MAX1541 Only)
Shutdown Supply Current (V
CC
)
Shutdown Supply Current
(V
DD
, MAX1541 Only)
ON1 = ON2 = GND, V
LDOON
= V+ = 28V
ON1 = ON2 = LDOON = GND
ON1 = ON2 = LDOON = GND
MAX1540A: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
CC
= 0 or 5V
MAX1541: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
CC
= V
DD
= 0 or 5V
Shutdown Supply Current
(LDOIN, MAX1541 Only)
PWM CONTROLLERS
V
OUT1
Preset output,
V+ = 5.5V to 28V,
SKIP
= V
CC
FB1 = GND
FB1 = V
CC
1.782
1.188
0.693
2.475
1.485
0.693
0.693
2.475
1.782
0.693
1.80
1.20
0.70
2.50
1.50
0.70
0.70
2.50
1.80
0.70
0.1
0.25
-0.1
0.7
+0.1
5.5
1.818
1.212
0.707
2.525
1.515
0.707
0.707
2.525
1.818
0.707
%
%
µA
V
V
V
V
V
LDOON = GND
<1
<1
4
<1
4
<1
MIN
TYP
<1
MAX
5
105
µA
5
100
5
5
15
µA
5
10
µA
µA
µA
µA
UNITS
µA
Standby Supply Current (V+)
Shutdown Supply Current (V+)
MAX1540A Main Output-Voltage
Accuracy (OUT1) (Note 2)
V
FB1
Adjustable output, V+ = 5.5V to 28V,
SKIP
= V
CC
Preset output,
V+ = 5.5V to 28V,
SKIP
= V
CC
FB2 = GND
FB2 = V
CC
MAX1540A Secondary Output-
Voltage Accuracy (OUT2)
(Note 2)
V
OUT2
V
FB2
V
FB1
Adjustable output, V+ = 5.5V to 28V,
SKIP
= V
CC
V+ = 4.5V to 28V,
SKIP
= V
CC
Preset output,
V+ = 4.5V to 28V,
SKIP
= V
CC
REFIN1 = 0.35 x REF
FB2 = GND
FB2 = V
CC
MAX1541 Main Feedback-
Voltage Accuracy (FB1)
MAX1541 Secondary Output-
Voltage Accuracy (OUT2)
(Note 2)
Load-Regulation Error
Line-Regulation Error
FB_ Input Bias Current
Output Adjust Range
V
OUT2
V
FB2
Adjustable output, V+ = 4.5V to 28V,
SKIP
= V
CC
I
LOAD
= 0 to 3A,
SKIP
= V
CC
V
CC
= 4.5V to 5.5V, V+ = 4.5V to 28V
I
FB
_
_______________________________________________________________________________________
3
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
MAX1540A/MAX1541
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V,
SKIP
= GND, LDOIN (MAX1541) = V+,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
SYMBOL
MAX1540A
OUT_ Input Resistance
R
OUT
_
MAX1541
CONDITIONS
FB_ = GND
FB_ = V
CC
or
adjustable
FB1 = OUT1
FB2 = GND
FB2 = V
CC
or
adjustable
OUT_ Discharge Mode On-
Resistance
OUT_ Synchronous-Rectifier
Discharge-Mode Turn-On Level
Soft-Start Ramp Time
t
SS
Rising edge on ON_ to full current limit
TON = GND (620kHz)
DH1 On-Time
t
ON1
V+ = 15V,
V
OUT1
= 1.5V
(Note 3)
TON = REF (485kHz)
TON = open (345kHz)
TON = V
CC
(235kHz)
TON = GND (460kHz)
DH2 On-Time
t
ON2
V+ = 15V,
V
OUT2
= 1.5V
(Note 3)
TON = REF (355kHz)
TON = open (255kHz)
TON = V
CC
(170kHz)
On-Time Tracking
Minimum Off-Time
MAX1540A LDO Output-Voltage
Accuracy
MAX1541 LDO Output-Voltage
Accuracy (Fixed V
LDOOUT
)
t
OFF(MIN)
LINEAR REGULATOR (LDO)
(Note 1)
V
LDOOUT
ON1 = ON2 = GND,
V+ = 6V to 28V
FBLDO = ON1 =
ON2 = GND,
V
LDOIN
= 6V to 28V
FBLDO = LDOOUT,
ON1 = ON2 = GND,
V
LDOIN
= 4.5V to
28V
0 < I
LDOOUT
< 10mA
0 < I
LDOOUT
< 100mA
0 < I
LDOOUT
< 10mA
0 < I
LDOOUT
< 100mA
0 < I
LDOOUT
< 10mA
0 < I
LDOOUT
< 100mA
4.85
4.70
4.85
4.70
1.212
1.175
1.175
130
I
FBLDO
MAX1540A: V+ - V
LDOOUT
, I
LDOOUT
= 50mA
Dropout Voltage
MAX1541: V
LDOIN
- V
LDOOUT
,
I
LDOOUT
= 50mA
-0.1
500
500
+0.1
800
800
mV
1.25
5.0
5.0
5.10
5.10
5.10
V
5.10
1.275
V
1.275
24
V
mA
µA
V
t
ON2
with respect to t
ON1
(Note 3)
(Note 3)
149
191
274
402
201
260
371
556
120
R
DISCHARGE
0.2
MIN
70
50
400
90
60
TYP
145
115
700
170
130
10
0.3
1.7
169
216
304
447
228
296
412
618
135
400
190
242
335
491
256
331
453
679
150
500
%
ns
ns
ns
MAX
350
220
1500
350
270
25
0.4
Ω
V
ms
kΩ
UNITS
V
LDOOUT
MAX1541 LDO Feedback
Accuracy (Adjustable V
LDOOUT
)
MAX1541 LDO Output
Adjust Range
LDOOUT Short-Circuit Current
FBLDO Input Bias Current
V
FBLDO
4
_______________________________________________________________________________________
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V,
SKIP
= GND, LDOIN (MAX1541) = V+,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
REFERENCE (REF)
Reference Voltage
Reference Load Regulation
REF Lockout Voltage
REFIN1 (MAX1541)
Voltage Range
REFIN1 (MAX1541)
Input Bias Current
FAULT DETECTION
Overvoltage Trip Threshold
Overvoltage Fault-Propagation
Delay
Output Undervoltage-Protection
Trip Threshold
Output Undervoltage-Protection
Blanking Time
Output Undervoltage Fault-
Propagation Delay
PGOOD_ Lower Trip Threshold
PGOOD_ Upper Trip Threshold
PGOOD_ Propagation Delay
PGOOD_ Output Low Voltage
PGOOD_ Leakage Current
Fault-Blanking Time
(MAX1541 Only)
Thermal-Shutdown Threshold
V
CC
Undervoltage-Lockout
Threshold
CURRENT LIMIT
ILIM_ Adjustment Range
Current-Limit Input Range
CSP_/CSN_ Input Current
CSP_
CSN_
0.25
0
-0.3
2
2.7
+28
0.5
V
V
µA
I
PGOOD
_
t
PGOOD
_
t
BLANK
t
UVP
With respect to error-comparator threshold,
hysteresis = 1%
With respect to error-comparator threshold,
hysteresis = 1%
FB forced 2% beyond PGOOD_ trip threshold
I
SINK
= 4mA
FB = REF (PGOOD high impedance),
PGOOD forced to 5.5V
FBLANK = V
CC
t
FBLANK
FBLANK = open
FBLANK = REF
T
SHDN
V
UVLO(VCC)
Hysteresis = 10°C
LDOON = V
CC
LDOON = GND
4.1
120
80
35
220
140
65
+150
+160
4.25
4.4
-13
+7
t
OVP
With respect to error-comparator threshold,
OVP/UVP = V
CC
FB forced 2% above trip threshold
With respect to error-comparator threshold,
OVP/UVP = V
CC
From rising edge of ON_
65
10
10
-10
+10
10
0.3
1
320
205
95
°C
V
µs
-7
+13
12
16
10
70
75
35
20
%
µs
%
ms
µs
%
%
µs
V
µA
V
REF
ΔV
REF
V
CC
= 4.5V to 5.5V,
I
REF
= 0V
I
REF
= -10µA to +50µA
T
A
= +25°C to +85°C
T
A
= 0°C to +85°C
1.986
1.983
-0.01
1.95
0.7
0.01
V
REF
0.05
2.00
2.00
2.014
2.017
+0.01
V
V
V
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1540A/MAX1541
V
REF(UVLO)
Rising edge, hysteresis = 350mV
V
REFIN
I
REFIN1
Rising edge, PWM disabled below this
level, hysteresis = 20mV
_______________________________________________________________________________________
5
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