Rainbow Electronics MAX1541 User Manual
General Description
The MAX1540/MAX1541 dual pulse-width modulation
(PWM) controllers provide the high efficiency, excellent
transient response, and high DC-output accuracy necessary for stepping down high-voltage batteries to generate 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 characteristics. 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 controllers can use the synchronous rectifier itself or lossless inductor current-sensing methods to provide
overload protection with lower power dissipation.
For a single step-down PWM controller with inductorsaturation protection, external-reference input voltage,
and dynamically selectable output voltages, refer to the
MAX1992/MAX1993 data sheet.
Applications
Notebook Computers
Core/IO 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)
Features
♦ Inductor-Saturation Protection
♦ Accurate Differential Current-Sense Inputs
♦ Dual Ultra-High-Efficiency Quick-PWMs with
100ns Load-Step Response
♦ MAX1540
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
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
________________________________________________________________ Maxim Integrated Products 1
THIN QFN
TOP VIEW
32313029282726
ON1
ON2
CSP1
CSN1
FB1
OUT1
PGOOD1
25 DH1
9
1011121314
15
CSP2
CSN2
FB2
OUT2
PGOOD2
DH2
LX2
16BST2
17
18
19
20
21
22
23
GND
DL2
V+
LDOOUT
DL1
LDOON
BST1
8
7
6
5
4
3
2
REF
ILIM2
ILIM1
V
CC
TON
LSAT
SKIP
MAX1540
1OVP/UVP
24 LX1
Pin Configurations
19-2861; Rev 0; 10/03
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.
EVALUATION KIT
AVAILABLE
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
*Future product—contact factory for availability.
Ordering Information
Pin Configurations continued at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX1540ETJ -40°C to +85°C 32 Thin QFN 5mm x 5mm
MAX1541ETL* -40°C to +85°C 40 Thin QFN 6mm x 6mm
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
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.
Note 1: For the MAX1540, the gate-driver input supply (VDD) 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+).
V+, LDOON to GND ...............................................-0.3V to +28V
LDOOUT to GND (MAX1540, 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
MAX154_ET_ ...................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
INPUT SUPPLIES (Note 1)
Quiescent Supply Current (VCC)I
Quiescent Supply Current
(V
Quiescent Supply Current (V+) I
Quiescent Supply Current
(LDOIN, MAX1541 Only)
Standby Supply Current (VCC) ON1 = ON2 = GND, V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX1540: battery voltage, V+ > V
IN
MAX1541: battery voltage, V+ > V
V
MAX1541: LDO input supply,
V
FB1 and FB2 forced above the regulation
point, LSAT = GND
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
MAX1540: FB1 and FB2 forced above the
regulation point, ON1 or ON2 = V
V
MAX1541: ON1 or ON2 = VCC,
V
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
V
CC, VDD
LDOIN
LDOON
LDOON
LDOON
(MAX1541) 4.5 5.5Input Voltage Range
> V
LDOOUT
= V+ = 28V
= V+ = 28V
= V+ = 28V
, MAX1541 Only)
DD
V
V
BIAS
V
LDOIN
CC
I
DD
V+
I
LDOIN
LDOOUT
LDOOUT
, V
CC
CC
CC
LDOON
> 0.5V
LSAT
,
CC
,
= V+ = 28V <1 5 µA
5.5 28
228
4.5 28
0.7 1.5
1.8
<1 5 µA
150
25 40
110 µA
V
mA
µA
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Standby Supply Current
(V
Standby Supply Current (V+)
Standby Supply Current
(LDOIN, MAX1541 Only)
Shutdown Supply Current (VCC) ON1 = ON2 = LDOON = GND <1 5 µA
Shutdown Supply Current
(V
Shutdown Supply Current (V+)
Shutdown Supply Current
(LDOIN, MAX1541 Only)
PWM CONTROLLERS
MAX1540 Main Output-Voltage
Accuracy (OUT1) (Note 2)
MAX1540 Secondary OutputVoltage Accuracy (OUT2)
(Note 2)
MAX1541 Main FeedbackVoltage Accuracy (FB1)
MAX1541 Secondary OutputVoltage Accuracy (OUT2)
(Note 2)
Load-Regulation Error I
Line-Regulation Error VCC = 4.5V to 5.5V, V+ = 4.5V to 28V 0.25 %
FB_ Input Bias Current IFB_ -0.1 +0.1 µA
Output Adjust Range 0.7 5.5 V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
, MAX1541 Only)
DD
, MAX1541 Only)
DD
V
V
V
V
V
V
V
OUT1
FB1
OUT2
FB2
FB1
OUT2
FB2
ON1 = ON2 = GND, V
MAX1540: ON1 = ON2 = GND,
LDOON = V+ = 28V, V
MAX1541: ON1 = ON2 = GND,
LDOON = V+ = 28V, V
ON1 = ON2 = GND, V
ON1 = ON2 = LDOON = GND <1 5 µA
MAX1540: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
MAX1541: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
LDOON = GND 4 10 µA
Preset output,
V+ = 5.5V to 28V,
SKIP = V
Adjustable output, V+ = 5.5V to 28V,
SKIP = V
Preset output,
V+ = 5.5V to 28V,
SKIP = V
Adjustable output, V+ = 5.5V to 28V,
SKIP = V
V+ = 4.5V to 28V,
SKIP = V
Preset output,
V+ = 4.5V to 28V,
SKIP = V
Adjustable output, V+ = 4.5V to 28V,
SKIP = V
= 0 to 3A, SKIP = V
LOAD
= 0 or 5V
CC
= VDD = 0 or 5V
CC
CC
CC
CC
CC
CC
CC
CC
= V+ = 28V <1 5 µA
LDOON
= 0 or 5V
CC
= VDD = 0 or 5V
CC
= V+ = 28V 100 µA
LDOON
FB1 = GND 1.782 1.80 1.818
FB1 = V
CC
FB2 = GND 2.475 2.50 2.525
FB2 = V
CC
REFIN1 = 0.35 x REF 0.693 0.70 0.707 V
FB2 = GND 2.475 2.50 2.525
FB2 = V
CC
CC
1.188 1.20 1.212
0.693 0.70 0.707
1.485 1.50 1.515
0.693 0.70 0.707
1.782 1.80 1.818
0.693 0.70 0.707
<1 5
415
<1 5
0.1 %
105
µA
µA
V
V
V
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
)
OUT_ Input Resistance R
OUT_ Discharge Mode OnResistance
OUT_ Synchronous-Rectifier
Discharge-Mode Turn-On Level
Soft-Start Ramp Time t
DH1 On-Time t
DH2 On-Time t
On-Time Tracking t
Minimum Off-Time t
LINEAR REGULATOR (LDO) (Note 1)
MAX1540 LDO Output-Voltage
Accuracy
MAX1541 LDO Output-Voltage
Accuracy (Fixed V
MAX1541 LDO Feedback
Accuracy (Adjustable V
MAX1541 LDO Output
Adjust Range
LDOOUT Short-Circuit Current 130 mA
FBLDO Input Bias Current I
Dropout Voltage
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FB_ = GND 70 145 350
OUT
R
D IS C H ARGE
MAX1540
_
MAX1541
FB_ = V
adjustable
CC
or
50 115 220
FB1 = OUT1 400 700 1500
FB2 = GND 90 170 350
CC
or
60 130 270
FB2 = V
adjustable
10 25 Ω
0.2 0.3 0.4 V
SS
ON1
Rising edge on ON_ to full current limit 1.7 ms
V+ = 15V,
= 1.5V
V
OUT1
(Note 3)
TON = GN D ( 620kH z)
TON = REF (485kHz) 191 216 242
TON = op en ( 345kH z) 274 304 335
TON = V
(235kHz) 402 447 491
CC
149 169 190
TON = GN D ( 460kH z) 201 228 256
LDOOUT
LDOOUT
V+ = 15V,
= 1.5V
V
ON2
OUT2
(Note 3)
with respect to t
ON2
OFF(MIN
V
LDOOUT
(Note 3) 400 500 ns
ON1 = ON2 = GND,
V+ = 6V to 28V
FBLDO = ON1 =
V
)
LDOOUT
ON2 = GND,
V
= 6V to 28V
LDOIN
FBLDO = LDOOUT,
V
FBLDO
)
ON1 = ON2 = GND,
V
= 4.5V to
LDOIN
28V
TON = REF (355kHz) 260 296 331
TON = op en ( 255kH z) 371 412 453
TON = V
(Note 3) 120 135 150 %
ON1
0 < I
0 < I
0 < I
0 < I
0 < I
0 < I
(170kHz) 556 618 679
CC
LDOOUT
LD OOU T
LDOOUT
LD OOU T
LDOOUT
LD OOU T
< 10mA 4.85 5.0 5.10
< 100m A 4.70 5.10
< 10mA 4.85 5.0 5.10
< 100m A 4.70 5.10
< 10mA 1.212 1.25 1.275
< 100m A 1.175 1.275
1.175 24 V
FBLDO
MAX1540: V+ - V
MAX1541: V
LDOIN
LDOOUT
- V
LDOOUT
-0.1 +0.1 µA
500 800
500 800
kΩ
ns
ns
V
V
V
mV
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
)
)
REFERENCE (REF)
Reference Voltage V
Reference Load Regulation ∆V
REF Lockout Voltage V
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 FaultPropagation Delay
PGOOD_ Lower Trip Threshold
PGOOD_ Upper Trip Threshold
PGOOD_ Propagation Delay t
PGOOD_ Output Low Voltage I
PGOOD_ Leakage Current I
Fault-Blanking Time
(MAX1541 Only)
Thermal-Shutdown Threshold T
VCC Undervoltage-Lockout
Threshold
CURRENT LIMIT
ILIM_ Adjustment Range 0.25 2 V
Current-Limit Input Range
CSP_/CSN_ Input Current 0.5 µA
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
REF
REFIREF
REF(UVLO
V
REFIN
I
REFIN1
t
OVP
t
BLANK
t
UVP
PGOOD
PGOOD
t
FBLANK
SHDN
V
UVLO(VCC
VCC = 4.5V to 5.5V,
= 0V
I
REF
= -10µA to +50µA -0.01 +0.01 V
Rising edge, hysteresis = 350mV 1.95 V
With respect to error-comparator threshold,
OVP/UVP = V
FB forced 2% above trip threshold 10 µs
With respect to error-comparator threshold,
OVP/UVP = V
From rising edge of ON_ 10 35 ms
With respect to error-comparator threshold,
hysteresis = 1%
With respect to error-comparator threshold,
hysteresis = 1%
FB forced 2% beyond P GOOD _ trip threshold
_
= 4mA 0.3 V
SINK
FB = REF (PGOOD high impedance),
_
PGOOD forced to 5.5V
FBLANK = V
FBLANK = open 80 140 205
FBLANK = REF 35 65 95
Hysteresis = 10°C
Rising edge, PWM disabled below this
level, hysteresis = 20mV
CSP_ 0 2.7
CSN_ -0.3 +28
CC
CC
CC
TA = + 25° C to + 85° C 1.986 2.00 2.014
T
= 0° C to +85°C 1.983 2.00 2.017
A
0.7 V
0.01 0.05 µA
12 16 20 %
65 70 75 %
10 µs
-13 -10 -7 %
+7 +10 +13 %
10 µs
120 220 320
LDOON = V
LDOON = GND +160
CC
4.1 4.25 4.4 V
+150
REF
1µA
V
V
µs
°C
V
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
6 _______________________________________________________________________________________
Dual Mode is a trademark of Maxim Integrated Products, Inc.
)
)
)
(
)
)
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Valley Current-Limit Threshold
(Fixed)
Valley Current-Limit Threshold
(Adjustable)
Current-Limit Threshold
(Negative)
Current-Limit Threshold
(Zero Crossing)
Inductor-Saturation Current-Limit
Threshold
ILIM_ Saturation Fault Sink
Current
ILIM_ Leakage Current
GATE DRIVERS
DH_ Gate-Driver On-Resistance R
DL_ Gate-Driver On-Resistance R
DH_ Gate-Driver Source/Sink
Current
DL_ Gate-Driver Source Current
DL_ Gate-Driver Sink Current I
Dead Time t
INPUTS AND OUTPUTS
OD On-Resistance R
OD Leakage Current GATE = GND, OD forced to 5.5V 1 200 nA
Logic Input Threshold
LDOON Input Trip Level Rising edge, hysteresis = 250mV 1.20 1.25 1.30 V
Logic Input Current ON1, ON2, LDOON, SKIP, GATE -1 +1 µA
Dual Mode™ Threshold Voltage
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
V
LIM_ (VAL
V
LIM_ (VAL
V
NEG
CSP
V
CSP
V
CSP
= +25°C
T
A
_ - V
_ - V
_ - V
_, ILIM_ = V
CSN
_
CSN
_, SKIP = ILIM_ = VCC,
CSN
CC
V
_ = 250mV 15 25 35
ILIM
V
_ = 2.00V 170 200 230
ILIM
45 50 55 mV
-90 -65 -45 mV
V
With respect to valley current-limit
V
ZX
I
ILIM_ (LSAT
DH
DL
I
DH
I
DL
SOURCE
DL (SINK
DEAD
OD
CC
CSP
_ - V
threshold, V
ILIM_ = V
With respect to
valley currentlimit threshold,
ILIM_ = V
V
CSP
limit, 0.25V < V
V
CSP
CC
- V
> inductor saturation current
CSN
ILIM
_ - V
< inductor saturation current
CSN _
limit
BST_-LX_ forced to 5V 1.5 5 Ω
DL_, high state 1.5 5
DL_, low state 0.6 3
DH_ forced to 2.5V, BST_-LX_ forced to 5V 1 A
DL_ forced to 2.5V 1 A
DL_ forced to 2.5V 3 A
DL_ rising 35
DH_ rising 26
GATE = V
CC
ON1, ON2, SKIP, GATE rising edge,
hysteresis = 225mV
FB1 (MAX1540),
_, SKIP = GND,
CSN
LSAT = V
CC
180 200 220
2.5 mV
LSAT = open 157 175 193
LSAT = REF 135 150 165
_ < 2.0V
468µA
0.1 µA
10 25 Ω
1.2 1.7 2.2 V
High 1.9 2.0 2.1
FB2 (MAX1540/
MAX1541)
Low 0.05 0.1 0.15
mV
%
Ω
ns
V
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
ELECTRICAL CHARACTERISTICS
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER
CONDITIONS
INPUT SUPPLIES (Note 1)
MAX1540: battery voltage, V+ > V
LDOOUT
5.5 28
V
IN
MAX1541: battery voltage, V+ > V
LDOOUT
228
V
BIAS
V
CC, VDD
(MAX1541) 4.5 5.5Input Voltage Range
V
LDOIN
MAX1541: LDO input supply,
V
LDOIN
> V
LDOOUT
4.5 28
V
FB1 and FB2 forced above the regulation
point, LSAT = GND
1.5
Quiescent Supply Current (VCC)I
CC
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
, V
LSAT
> 0.5V
1.8
mA
Quiescent Supply Current
(V
DD
, MAX1541 Only)
I
DD
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
5µA
MAX1540: FB1 and FB2 forced above the
regulation point, ON1 or ON2 = V
CC
,
V
LDOON
= V+ = 28V
150
Quiescent Supply Current (V+) I
V+
MAX1541: ON1 or ON2 = VCC, V
LDOON
=
V+ = 28V
40
µA
Quiescent Supply Current
(LDOIN, MAX1541 Only)
I
LDOIN
FB1 and FB2 forced above the regulation
point, ON1 or ON2 = V
CC
,
V
LDOON
= V+ = 28V
110 µA
Standby Supply Current (VDD) ON1 = ON2 = GND, V
LDOON
= V+ = 28V 5 µA
Standby Supply Current
(V
DD
, MAX1541 Only)
ON1 = ON2 = GND, V
LDOON
= V+ = 28V 5 µA
MAX1540: ON1 = ON2 = GND, LDOON =
V+ = 28V, V
CC
= 0 or 5V
105
Standby Supply Current (V+)
MAX1541: ON1 = ON2 = GND, LDOON =
V+ = 28V, V
CC
= VDD = 0 or 5V
5
µA
Standby Supply Current
(LDOIN, MAX1541 Only)
ON1 = ON2 = GND, V
LDOON
= V+ = 28V 100 µA
Four-Level Input Logic Levels
Four-Level Logic Input Current
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TON, OVP/UVP,
LSAT, SKIP,
FBLANK
TON, OVP/UVP, LSAT, SKIP, FBLANK
forced to GND or V
SYMBOL
V
High
Open 3.15 3.85
REF 1.65 2.35
Low 0.5
CC
CC
0.4V
-3 +3 µA
MIN MAX UNITS
-
V
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
8 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER
CONDITIONS
UNITS
Shutdown Supply Current (VCC) ON1 = ON2 = LDOON = GND 5 µA
Shutdown Supply Current
(V
DD
, MAX1541 Only)
ON1 = ON2 = LDOON = GND 5 µA
MAX1540: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
CC
= 0 or 5V
15
Shutdown Supply Current (V+)
MAX1541: ON1 = ON2 = LDOON = GND,
V+ = 28V, V
CC
= VDD = 0 or 5V
5
µA
Shutdown Supply Current
(LDOIN, MAX1541 Only)
LDOON = GND 10 µA
PWM CONTROLLERS
FB1 = GND
V
OUT1
Preset output,
V+ = 5.5V to 28V,
SKIP = V
CC
FB1 = V
CC
MAX1540 Main Output-Voltage
Accuracy (OUT1) (Note 2)
V
FB1
Adjustable output, V+ = 5.5V to 28V,
SKIP = V
CC
V
FB2 = GND
V
OUT2
Preset output,
V+ = 5.5V to 28V,
SKIP = V
CC
FB2 = V
CC
MAX1540 Secondary OutputVoltage Accuracy (OUT2)
(Note 2)
V
FB2
Adjustable output, V+ = 5.5V to 28V,
SKIP = V
CC
V
MAX1541 Main Feedback
Voltage Accuracy (FB1)
V
FB1
V+ = 4.5V to 28V,
SKIP = V
CC REFIN1 = REF
V
FB2 = GND
V
OUT2
Preset output,
V+ = 4.5V to 28V,
SKIP = V
CC
FB2 = V
CC
MAX1541 Secondary OutputVoltage Accuracy (OUT2)
(Note 2)
V
FB2
Adjustable output, V+ = 4.5V to 28V,
SKIP = V
CC
V
190
242
335
DH1 On-Time (Note 3) t
ON1
V+ = 15V,
V
OUT1
= 1.5V
491
ns
256
331
453
DH2 On-Time (Note 3) t
ON2
V+ = 15V,
V
OUT2
= 1.5V
679
ns
On-Time Tracking t
ON2
with respect to t
ON1
(Note 3)
152 %
Minimum Off-Time
)
(Note 3) 500 ns
LINEAR REGULATOR (LDO) (Note 1)
MAX1540 LDO Output-Voltage
Accuracy
ON1 = ON2 = GND,
V+ = 6V to 28V
V
SYMBOL
MIN MAX
t
OFF(MIN
V
LDOOUT
1.773 1.827
1.182 1.218
0.689 0.711
2.462 2.538
1.477 1.523
0.689 0.711
REFIN1 = 0.35 x REF 0.689 0.711
1.97 2.03
2.462 2.538
1.773 1.827
0.689 0.711
TON = G N D ( 620kH z) 149
TON = RE F ( 485kH z) 191
TON = op en ( 345kH z) 274
TON = V CC ( 235kH z) 402
TON = G N D ( 460kH z) 201
TON = RE F ( 355kH z) 260
TON = op en ( 255kH z) 371
TON = V CC ( 170kH z) 556
0 < I
0 < I
LDOOUT
L D OOU T
< 10mA 4.85 5.10
< 100m A 4.65 5.10
118
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
_______________________________________________________________________________________ 9
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER
CONDITIONS
UNITS
MAX1541 LDO Output-Voltage
Accuracy (Fixed V
LDOOUT
)
FBLDO = ON1 =
ON2 = GND,
V
MAX1541 LDO Feedback
Accuracy (Adjustable V
LDOOUT
)
FBLDO = LDOOUT,
ON1 = ON2 = GND,
V
LDOIN
= 4.5V to
28V
V
MAX1540: V+ - V
LDOOUT
800
Dropout Voltage
MAX1541: V
LDOIN
- V
LDOOUT
800
mV
REFERENCE (REF)
Reference Voltage V
REF
VCC = 4.5V to 5.5V, I
REF
= 0
V
REFIN1 Input Bias Current I
REFIN1
µA
FAULT DETECTION
Overvoltage Trip Threshold
With respect to error-comparator threshold,
OVP/UVP = V
CC
10 21 %
Output Undervoltage-Protection
Trip Threshold
With respect to error-comparator threshold,
OVP/UVP = V
CC
64 76 %
PGOOD_ Lower Trip Threshold
With respect to error-comparator threshold,
hysteresis = 1%
-14 -5 %
PGOOD_ Upper Trip Threshold
With respect to error-comparator threshold,
hysteresis = 1%
+5
%
PGOOD_ Output Low Voltage I
SINK
= 4mA 0.3 V
VCC Undervoltage-Lockout
Threshold
)
Rising edge, PWM disabled below this
level, hysteresis = 20mV
4.1 4.4 V
CURRENT LIMIT
CSP_ 0 2.7
Current-Limit Input Range
CSN_
V
Valley Current-Limit Threshold
(Fixed)
)
V
CSP
_ - V
CSN
_, ILIM_ = V
CC
40 60 mV
Valley Current-Limit Threshold
(Adjustable)
)
V
CSP
_ - V
CSN
_, V
ILIM
_ = 2.00V
240 mV
INPUTS AND OUTPUTS
Logic Input Threshold
ON1, ON2, SKIP, GATE, rising edge,
hysteresis = 225mV
1.2 2.2 V
LDOON Input Trip Level Rising edge, hysteresis = 250mV 1.2 1.3 V
High 1.9 2.1
Dual Mode Threshold Voltage
FB1 (MAX1540),
FB2 (MAX1540/MAX1541)
Low
V
SYMBOL
V
LDOOUT
V
FBLDO
V
UVLO(VCC
V
LIM_ (VAL
V
LIM_ (VAL
V
= 6V to 28V
LDOIN
0 < I
0 < I
L D OOU T
0 < I
0 < I
L D OOU T
< 10mA 4.85 5.10
LDOOUT
< 100m A 4.65 5.10
< 10mA 1.212 1.275
LDOOUT
< 100m A 1.175 1.275
MIN MAX
1.98 2.02
-0.3 +28.0
160
0.05 0.15
0.05
+14
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
10 ______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, VCC= VDD= ON1 = ON2 = 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
MAX
UNITS
High
V
CC
-
Open
REF
Four-Level Input Logic Levels
TON, OVP/UVP, LSAT, SKIP,
FBLANK
Low 0.5
V
Note 1: For the MAX1540, the gate-driver input supply (VDD) 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+).
Note 2: When the inductor is in continuous conduction, the output voltage has a DC regulation level higher than the error-comparator
threshold by 50% of the ripple. In discontinuous conduction (SKIP = GND, light load), the output voltage has a DC regulation
level higher than the trip level by approximately 1.5% due to slope compensation.
Note 3: On-time and off-time specifications are measured from 50% point to 50% point at the DH_ pin with LX_ = GND, VBST_ = 5V,
and a 250pF capacitor connected from DH_ to LX_. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 4: Specifications to -40°C are guaranteed by design, not production tested.
OUT2 EFFICIENCY vs. LOAD CURRENT
(V
OUT2
= 2.5V)
MAX1540 toc01
LOAD CURRENT (A)
EFFICIENCY (%)
10.1
55
60
65
70
75
80
85
90
95
100
50
0.01 10
SKIP = GND
SKIP = V
CC
VIN = 7V
VIN = 12V
VIN = 20V
2.5V OUTPUT VOLTAGE (OUT2)
vs. LOAD CURRENT
MAX1540 toc02
LOAD CURRENT (A)
OUTPUT VOLTAGE (V)
4321
2.49
2.50
2.51
2.52
2.53
2.54
2.55
2.48
05
SKIP = GND
SKIP = V
CC
OUT1 EFFICIENCY vs. LOAD CURRENT
(V
OUT1
= 1.0V)
MAX1540 toc03
LOAD CURRENT (A)
EFFICIENCY (%)
10.1
55
60
65
70
75
80
85
90
95
100
50
0.01 10
SKIP = GND
SKIP = V
CC
VIN = 7V
VIN = 12V
VIN = 20V
Typical Operating Characteristics
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
0.4V
3.15 3.85
1.65 2.35
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
______________________________________________________________________________________ 11
)
Typical Operating Characteristics (continued)
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
1.0V OUTPUT VOLTAGE (OUT1)
vs. LOAD CURRENT
1.02
1.01
1.00
OUTPUT VOLTAGE (V)
0.99
0.98
05
LOAD CURRENT (A)
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
450
2.5V OUTPUT
SKIP = V
400
350
300
SWITCHING FREQUENCY (kHz)
250
200
CC
4A LOAD
NO LOAD
028
INPUT VOLTAGE (V)
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
(PULSE-SKIPPING OPERATION)
1.4
SKIP = GND
1.2
ON1 = ON2 = V
1.0
0.8
0.6
SUPPLY CURRENT (mA)
0.4
0.2
0
028
CC
INPUT VOLTAGE (V)
SKIP = GND
SKIP = V
431 2
CC
2420161284
600
500
MAX1540 toc04
400
300
200
SWITCHING FREQUENCY (kHz)
100
0
05
6.0
2.5V OUTPUT
5.8
MAX1540 toc07
5.6
5.4
5.2
5.0
4.8
4.6
4.4
MAXIMUM OUTPUT CURRENT (A)
4.2
4.0
028
2.0V REFERENCE LOAD REGULATION
4
MAX1540 toc10
I
BIAS
I
IN
2420161284
3
2
1
0
-1
-2
REFERENCE VOLTAGE DEVIATION (mV)
-3
-4
-20
OUT2 SWITCHING FREQUENCY
vs. LOAD CURRENT
= 2.5V)
(V
OUT2
SKIP = GND
SKIP = V
CC
4321
LOAD CURRENT (A)
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
INPUT VOLTAGE (V
0
REFERENCE LOAD CURRENT (µA)
40
20
80
60
OUT1 SWITCHING FREQUENCY
vs. LOAD CURRENT
= 1.0V)
(V
600
500
MAX1540 toc05
400
300
200
SWITCHING FREQUENCY (kHz)
100
0
05
20
MAX1540 toc08
16
12
8
SUPPLY CURRENT (mA)
4
SKIP = ON1 = ON2 = V
0
242012 1684
MAX1540 toc11
100
028
50
SAMPLE SIZE = 50
40
30
20
SAMPLE PERCENTAGE (%)
10
0
1.990 2.010
OUT1
SKIP = GND
SKIP = V
4321
LOAD CURRENT (A)
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
(FORCED-PWM OPERATION)
I
BIAS
I
IN
CC
INPUT VOLTAGE (V)
REFERENCE DISTRIBUTION
2.0052.0001.995
REFERENCE VOLTAGE (V)
MAX1540 toc06
CC
MAX1540 toc09
2420161284
MAX1540 toc12
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
12 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
LINEAR-REGULATOR OUTPUT (LDOOUT)
vs. LOAD CURRENT
MAX1540 toc13
LDO LOAD CURRENT (mA)
LDO OUTPUT VOLTAGE (V)
806020 40
3.22
3.24
3.26
3.28
3.30
3.32
3.34
3.36
3.20
0 100
V
LDOIN
= 5V
V
LDOIN
= 12V
STARTUP WAVEFORM
(HEAVY LOAD)
MAX1540 toc14
3.3V
0
2.5V
0
B
D
C
A
400µs/div
4A
2A
0
0
A. ON2, 5V/div
B. INDUCTOR CURRENT,
2A/div
0.5Ω LOAD
C. OUT2, 2V/div
D. PGOOD2, 5V/div
STARTUP WAVEFORM
(LIGHT LOAD)
MAX1540 toc15
3.3V
0
2.5V
0
B
D
C
A
200µs/div
4A
2A
0
0
A. ON2, 5V/div
B. INDUCTOR CURRENT,
2A/div
100Ω LOAD
C. OUT2, 2V/div
D. PGOOD2, 5V/div
SHUTDOWN WAVEFORM
(DISCHARGE MODE DISABLED)
MAX1540 toc16
3.3V
0
5V
0
B
D
C
A
10ms/div
2.5V
0
0
0
A. ON2, 5V/div
B. OUT2, 2V/div
C. INDUCTOR CURRENT,
2A/div
100Ω LOAD, OVP/UVP = REF OR GND
D. DL2, 5V/div
E. PGOOD2, 5V/div
5V
E
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
______________________________________________________________________________________ 13
Typical Operating Characteristics (continued)
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
SHUTDOWN WAVEFORM
(DISCHARGE MODE ENABLED)
MAX1540 toc17
3.3V
0
5V
0
B
D
C
A
1ms/div
2.5V
0
0
0
A. ON2, 5V/div
B. OUT2, 2V/div
C. INDUCTOR CURRENT,
2A/div
100Ω LOAD, OVP/UVP = V
CC
OR OPEN
D. DL2, 5V/div
E. PGOOD2, 5V/div
5V
E
2.5V OUTPUT LOAD TRANSIENT
(FORCED PWM)
MAX1540 toc18
4A
0
4A
0
B
D
C
A
40µs/div
2.5V
2.4V
2.6V
A. I
OUT2
= 0 TO 4A, 5A/div
B. V
OUT2
= 2.5V, 100mV/div
SKIP = V
CC
C. INDUCTOR CURRENT, 5A/div
D. LX2, 10V/div
12V
0
2.5V OUTPUT LOAD TRANSIENT
(PULSE SKIPPING)
MAX1540 toc19
4A
0
4A
0
B
D
C
A
40µs/div
2.5V
2.4V
2.6V
A. I
OUT2
= 0.1A TO 4A, 5A/div
B. V
OUT2
= 2.5V, 100mV/div
SKIP = GND
C. INDUCTOR CURRENT, 5A/div
D. LX2, 10V/div
12V
0
LINEAR-REGULATOR
LOAD TRANSIENT
MAX1540 toc20
100mA
0
B
A
100µs/div
3.3V
3.2V
3.4V
A. I
LDOOUT
= 1mA TO 100mA, 50mA/div
B. V
LDOOUT
= 3.3V, 100mV/div
SKIP = GND
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
14 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
LINEAR-REGULATOR
LINE TRANSIENT
MAX1540 toc21
20V
10V
20V
10V
3.8V
3.3V
2.8V
C
A
B
200µs/div
A. INPUT (V
IN
), 10V/div
B. LDOIN (10V TO 20V), 10V/div
C. LDOOUT (3.3V), 500mV/div
20mA LOAD
OUTPUT OVERLOAD
(UVP DISABLED)
MAX1540 toc22
20A
0
2.5V
10A
B
D
C
A
40µs/div
0
5A
0
5V
A. LOAD (0 TO 150mΩ), 10A/div
B. INDUCTOR CURRENT, 10A/div
OVP/UVP = OPEN OR GND
C. 2.5V OUTPUT, 2V/div
D. PGOOD2, 5V/div
0
OUTPUT OVERLOAD
(UVP ENABLED)
MAX1540 toc23
20A
0
2.5V
10A
B
D
C
A
20µs/div
0
5A
0
5V
A. LOAD (0 TO 150mΩ), 10A/div
B. INDUCTOR CURRENT, 10A/div
C. DL2, 5V/div
OVP/UVP = V
CC
OR REF
D. 2.5V OUTPUT, 2V/div
E. PGOOD2, 5V/div
E
0
5V
INDUCTOR-SATURATION PROTECTION
(LSAT DISABLED)
MAX1540 toc24
0
2.5V
B
D
C
A
20µs/div
5A
7.5A
A. I
OUT2
= 0 TO 5A, 5A/div
B. 2.5V OUTPUT, 200mV/div
LSAT = GND, L = 3.3µH 3.5A
C. ILIM, 100mV/div
D. INDUCTOR CURRENT, 5A/div
0.67V
0
MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
______________________________________________________________________________________ 15
Typical Operating Characteristics (continued)
(MAX1541 Circuit of Figure 12, V
IN
= 12V, VDD= VCC= 5V, SKIP = GND, TON = REF, TA = +25°C, unless otherwise noted.)
INDUCTOR-SATURATION PROTECTION
(∆V
ILIM
= 200mV)
MAX1540 toc25
0
2.5V
B
D
C
A
20µs/div
5A
7.5A
A. I
OUT2
= 0 TO 5A, 5A/div
B. 2.5V OUTPUT, 200mV/div
LSAT = REF, L = 3.3µH 3.5A
C. ILIM, 200mV/div
D. INDUCTOR CURRENT, 5A/div
0.67V
0
0.47V
INDUCTOR-SATURATION PROTECTION
(∆V
ILIM
= 400mV)
MAX1540 toc26
0
2.5V
1.5V
B
D
C
A
20µs/div
5A
5A
A. I
OUT2
= 0 TO 5A, 5A/div
B. 2.5V OUTPUT, 1V/div
C. PGOOD, 5V/div
LSAT = REF, L = 3.3µH 3.5A
D. ILIM, 400mV/div
E. INDUCTOR CURRENT, 5A/div
5V
0
0.67V
E
0.27V
MAX1541
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(C
REFIN1
= 100pF)
MAX1540 toc27
-5A
1.5V
B
D
C
A
40µs/div
5A
5A
A. GATE, 5V/div
B. OUT1 (1.0V TO 1.5V), 0.5V/div
C. REFIN1, 0.5V/div
200mA LOAD, SKIP = GND
D. PGOOD1, 5V/div
E. INDUCTOR CURRENT, 5A/div
1.5V
0
1V
E
5V
0
MAX1541
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(C
REFIN1
= 1nF)
MAX1540 toc28
-5A
1.5V
B
D
C
A
100µs/div
5A
5A
A. GATE, 5V/div
B. OUT1 (1.0V TO 1.5V), 0.5V/div
C. REFIN1, 0.5V/div
200mA LOAD, SKIP = GND
D. PGOOD1, 5V/div
E. INDUCTOR CURRENT, 5A/div
1.5V
0
1V
E
5V
0
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