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MAX17558
EVALUATION KIT AVAILABLE
60V, Dual-Output, Synchronous
Step-Down Controller
General Description
The MAX17558 is a dual-output, synchronous step-down
controller that drives nMOSFETs. The device uses a
constant-frequency, peak-current-mode architecture.
The two outputs can be configured as independent
voltage rails. Input capacitor size can be minimized by
running the two outputs 180º out-of-phase.
The IC supports current sensing using either an external
current-sense resistor for accuracy or an inductor DCR
for improved system efficiency. Current foldback limits
MOSFET power dissipation under short-circuit conditions.
The IC provides independent adjustable soft-start for
each output and can start up monotonically into a
prebiased output. The IC can be configured in either
PWM or DCM modes of operation, depending on whether
constant-frequency operation or light-load efficiency is
desired.
The IC operates over the -40°C to +125°C temperature
range and is available in a lead(Pb)-free, 32-pin TQFN,
5mm x 5mm package.
Applications
● Industrial Power Supplies
● Distributed DC Power Systems
● Motion Control
● Programmable Logic Controllers
● Computerized Numerical Control
Benefits and Features
● Wide Range of Operation
• Wide 4.5V to 60V Input Voltage Range
• Wide 0.8V to 24V Output Voltage Range
• RSENSE or Inductor DCR Current-Sensing
• Selectable In-Phase or 180° Out-of-Phase
Operation
• Adjustable 100kHz to 2.2MHz Switching Frequency
• Independent Enable and PGOOD
• Available in a Lead(Pb)-Free 32-Pin, 5mm x 5mm
TQFN Package
● Enhances Power Efficiency
• Low Impedence Gate Drives for High Efficiency
• DCM Operation at Light Loads
• Auxiliary Bootstrap LDO
● Operates Reliably in Adverse Industrial Environments
• Independent Adjustable Soft-Start or Tracking
• Current Foldback Limits MOSFET Heat Dissipation
During a Short-Circuit Condition
• Operates Over the -40°C to +125°C Temperature
Range
• Output Overvoltage and Overtemperature Protections
Ordering Information appears at end of data sheet.
19-7532; Rev 0; 3/15

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MAX17558
Block Diagram
PGOOD1 27
PGOOD2 14
RT 2
SKIP 5
10µA
0.8
8V
VFB1
0.72V
0.88V
VFB
2
0.72V
SEL_PH
3
OSC
TEST
4
CLK2
CLK1
100K
ILIM 28
CURRENT
LIMIT
IN 22
VCCEXT 20
4.7V
LDO
EN
LDO
EN
6 19
GND VCCINT
60V, Dual-Output, Synchronous
Step-Down Controller
DUPLICATE FOR SECOND
CONTROLLER CHANNEL
SQ
RQ
SKIP
CONTROL
LOGIC
VCCINT
21
BST_
24,17
DH_
26,15
LX_
25,16
DL_
23,18
PGND
ZX
SLOPE
COMP
EA 0.80V
SS_
CS_+
32,10
CS_-
1,9
FB_
31,11
1.8µA
COMP_
30,12
5µA
SS_
1.5V 29,13
EN_
7,8
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Maxim Integrated 2

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MAX17558
60V, Dual-Output, Synchronous
Step-Down Controller
Absolute Maximum Ratings
IN to GND...............................................................-0.3V to +70V
CS_+ to GND.........................................................-0.3V to +40V
CS_+ to CS_-........................................................-0.3V to +0.3V
LX_, BST_ to PGND..............................................-0.3V to +70V
BST_ to LX_.............................................................-0.3V to +6V
BST_ to VCCINT.....................................................-0.3V to +70V
DH_ to LX_.............................................-0.3V to (VBST_ + 0.3)V
DL_ to PGND....................................... -0.3V to (VCCINT + 0.3)V
EN_ to GND.............................................................-0.3V to +6V
VCCINT to GND........................................................-0.3V to +6V
VCCEXT to GND.....................................................-0.3V to +26V
PGND to GND.......................................................-0.3V to +0.3V
PGOOD_ to GND.....................................................-0.3V to +6V
FB_, COMP_, SS_, RT, SKIP, SEL_PH, ILIM
.......................................................... -0.3V to (VCCINT + 0.3)V
GND to EP.............................................................-0.3V to +0.3V
Continuous Power Dissipation at +70ºC
(Multilayer Board)....................................................2758.6mW
Power Deration (Multilayer Board)............................34.5 mW/°C
Operating Temperature Range.......................... -40°C to +125°C
Maximum Junction Temperature......................................+150°C
Storage Temperature Range............................. -65°C to +160°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.
Package Thermal Characteristics(Note 1)
Junction-to-Ambient Thermal Resistance (θJA)...............29°C/W
Junction to Case Thermal Resistance (θJC)...................1.7°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
(VIN = 24V, RT = open, CVCCINT = 4.7µF, EN_ = open, DH_, DL_ = open, TJ = -40°C to +125°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 2)
PARAMETER
INPUT SUPPLY
Input Voltage Range
Operating Supply Current
(Note 3)
Shutdown Supply Current
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VIN VCCINT = VIN
4.5 60
4.5 5.5
SKIP = open, LX_ = PGND, BST_ = 5V
EN1 = open, EN2 = GND, VFB1 = 0.84V or
0.5
1.5
2.0
EN2 = open, EN1 = GND, VFB2 = 0.84V
SKIP = open, LX_ = PGND, BST_ = 5V
IIN EN1 = EN2 = open, VFB1 = VFB1 = 0.84V
SKIP = VCCINT, LX_ = PGND, BST_ = 5V
EN1 = open, EN2 = GND, VFB1 = 0.76V or
EN2 = open, EN1 = GND, VFB2 = 0.76V
1
1
2.5 3.5
1.8 3.5
SKIP = VCCINT, LX_ = PGND,BST_=5V
EN1 = EN2 = open, VFB1 = VFB1 = 0.76V
1.5
3.2
5
EN1 = EN2 = GND
10 20
V
mA
mA
µA
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Maxim Integrated 3

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MAX17558
60V, Dual-Output, Synchronous
Step-Down Controller
Electrical Characteristics (continued)
(VIN = 24V, RT = open, CVCCINT = 4.7µF, EN_ = open, DH_, DL_ = open, TJ = -40°C to +125°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 2)
PARAMETER
VCCINT REGULATOR
VCCINT Output Voltage
VCCINT Load Regulation
VCCINT Short-Circuit Output
Current
VCCINT Dropout Voltage
VCCEXT Switch Overvoltage
VCCEXT Switch Overvoltage
Hysteresis
VCCINT UVLO
OSCILLATOR
Switching Frequency
RT Pullup Current
Switching Frequency
Adjustable Range
SKIP
DCM Mode Setting Range
PWM Mode Setting Range
SYMBOL
CONDITIONS
MIN
VCCINT
6V < VIN < 60V, IVCCINT = 1mA
6V < VCCEXT < 24V, IVCCINT = 1mA
(VCCINT supplied from VCCEXT)
VIN = 12V, I = 0mA to 100mA,
VCCEXT = 0V (VCCINT supplied from VIN)
VVCCEXT = 12V, IVCCINT = 0mA to 100mA
(VCCINT supplied from VCCEXT)
VIN = 8.5V, VCCEXT = 0V, VCCINT = 4V
VCCEXT = 8.5V, VCCINT = 4V
(VCCINT supplied from VCCEXT)
VIN = 4.5V, load = 75mA, VCCEXT = 0
VCCINT supplied from VCCEXT, VIN = 24V,
VCCEXT = 4.7V, load = 75mA
VCCEXT rising
VCCINT rising
VCCINT falling
4.95
4.95
5
5
120
120
50
50
4.55
0.2
4
3.5
RT = 62kΩ
fSW RT = VCCINT
RT = GND
VRT = 0.5V
fSW 26.5kΩ < RT < 280kΩ
405
480
325
9.5
100
1.25
VCCINT
- 1.5
TYP
5.1
5.1
25
25
250
250
150
150
4.7
0.25
4.2
3.7
440
535
350
10
MAX
UNITS
5.25
V
5.25
50
mV
50
340
mA
340
420
mV
420
4.85 V
0.3 V
4.4
V
3.9
475
590
375
10.5
2200
kHz
µA
kHz
VCCINT
- 1.6
VCCINT
V
V
SKIP Pulldown Resistance
70 100 130
kΩ
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Maxim Integrated 4

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MAX17558
60V, Dual-Output, Synchronous
Step-Down Controller
Electrical Characteristics (continued)
(VIN = 24V, RT = open, CVCCINT = 4.7µF, EN_ = open, DH_, DL_ = open, TJ = -40°C to +125°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
GATE DRIVER
DH_ to BST_ On-Resistance
Sourcing 100mA
DH_ to LX_ On-Resistance
Sinking 100mA
DL_ to VCCINT On-Resistance
DL_ to PGND_ On-Resistance
Sourcing 100mA
Sinking 100mA
DH_ Minimum Controlled
On-Time
tON_MIN
DL_ Minimum Controlled
Off-Time
tOFF_MIN PWM mode, VFB_ = 0.84V
Dead Time
DH_ Transition Time
DL_ Transition Time
SOFT-START
tDT
DH_ falling to DL_ rising, CLOAD = 6nF
DL_ falling to DH_ rising, CLOAD = 6nF
DH_ rising, CLOAD = 6nF
DH_ falling, CLOAD = 6nF
DL_ rising, CLOAD = 6nF
DL_ falling, CLOAD = 6nF
Soft-Start Current
ENABLE
ISS VSS = 0.5V
EN_ Logic-High Threshold
EN_ rising
EN_ Hysteresis
EN_Bias Pullup Bias Current
CURRENT-SENSE AMPLIFIER
VEN = 0.5V
CS_+ , CS_- Common-Mode
Voltage Range
CS_+ to CS_- Input
Operating Voltage Range
VCS+ -
VCS-
0 < VCS- < 24V
ILIM = GND
Current-Sense Amplifier Gain
ILIM = open
CS+_ Input Bias Current
CS-_ Input Bias Current
VILIM = VCCINT
0 < VCS- < 24V, TA = TJ = 25°C
VCS+ = VCS- = 1.2V or 24V
MIN
TYP
MAX
UNITS
0.7 1.3 2.5
0.25 0.5
0.9
0.7 1.3 2.5
0.35 0.75 1.25
120 155
80 120 160
30
30
25
15
25
15
ns
ns
ns
ns
ns
3.5 5 6.5 µA
1.2 1.25 1.3
90
0.9 1.8 2.7
V
mV
µA
0 24
-100
+100
30 33.3 36.6
18 20 22
12 13.3 14.5
0.01 1
5 600
V
mV
V/V
µA
µA
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Maxim Integrated 5