MAX16961
3A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
General Description
The MAX16961 is a high-efficiency, synchronous step-
down converter that operates with a 2.7V to 5.5V input
voltage range and provides a 0.8V to 3.6V output voltage
range. The wide input/output voltage range and the ability
to provide up to 3A to load current make this device ideal
for on-board point-of-load and post-regulation applica-
tions. The device achieves -3.7%/+2.6% output error over
load, line, and temperature ranges.
The device features a 2.2MHz fixed-frequency PWM
mode for better noise immunity and load transient
response, and a pulse-frequency modulation mode
(skip) for increased efficiency during light-load operation.
The 2.2MHz frequency operation allows for the use of all-
ceramic capacitors and minimizes external components.
The optional spread-spectrum frequency modulation
minimizes radiated electromagnetic emissions.
Integrated low R
DSON
switches improve efficiency at
heavy loads and make the layout a much simpler task
with respect to discrete solutions.
The device can be offered with factory-preset output volt-
ages, or with an adjustable output voltage (contact factory
for preset output-voltage options). Factory-preset output-
voltage versions allow customers to achieve -3.7%/+2.6%
output-voltage accuracy without using external resistors,
while the adjustable output-voltage version provides the
flexibility to set the output voltage to any desired value
between 0.8V to 3.6V using an external resistive divider.
Additional features include 8ms soft-start, 16ms power-
good output delay, overcurrent, and overtemperature
protections.
The MAX16961 is available in thermally enhanced
16-pin TSSOP-EP and 16-pin (4mm x 4mm) TQFN-EP
packages, and is specified for operation over the -40NC
to +125NC automotive temperature range.
Benefits and Features
S
Small External Components
2.2MHz Operating Frequency
S
Ideal for Point-of-Load Applications
3A Maximum Load Current
Adjustable Output Voltage: 0.8V to 3.6V
2.7V to 5.5V Operating Supply Voltage
S
High Efficiency at Light Load
26µA Skip Mode Quiescent Current
S
Minimizes Electromagnetic Interference
Programmable SYNC I/O Pin
Operates Above AM-Radio Band
Available Spread Spectrum
S
Low Power Mode Saves Energy
1µA Shutdown Current
S
Open-Drain Power-Good Output
S
Limits Inrush Current During Startup
Soft-Start
S
Overtemperature and Short-Circuit Protections
S
16-Pin TSSOP-EP and 16-Pin (4mm x 4mm)
TQFN-EP Packages
S
-40°C to 125°C Operating Temperature Range
Applications
Automotive Infotainment
Point-of-Load Applications
Industrial/Military
Typical Application Circuit
V
PV1
PV1
4.7µF
OUTS
0.47µH
LX1
LX2
PGND1
V
PV
10Ω
PV
1µF
GND
PGND2
V
OUT1
20kΩ
PG
V
OUT1
47µF
Ordering Information
appears at end of data sheet.
PV2
EN
MAX16961
EP
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-6520; Rev 5; 6/15
MAX16961
3A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
ABSOLUTE MAXIMUM RATINGS
PV, PV1, PV2 to GND ..............................................-0.3V to +6V
EN, PG to GND .......................................................-0.3V to +6V
PGND1 and PGND2 to GND ..............................-0.3V to +0.3V
LX1, LX2 Continuous RMS Current
(LX1 connected in Parallel with LX2)...................................4A
LX Current (LX1 connected in Parallel with LX2).....Q6A (Note 5)
All Other Pins Voltages to GND .. (V
PV
+ 0.3V) to (V
GND
- 0.3V)
Output Short-Circuit Duration ....................................Continuous
*As
per JEDEC51 Standard (multilayer board).
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
Continuous Power Dissipation (T
A
= +70NC)
TQFN (derate 25mW/NC above +70NC)................... 2000mW*
TSSOP (derate 26.1mW/NC above +70NC)........... 2088.8mW*
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TQFN
Junction-to-Ambient Thermal Resistance (B
JA
) ..........40NC/W
Junction-to-Case Thermal Resistance (B
JC
) .................6NC/W
TSSOP
Junction-to-Ambient Thermal Resistance (B
JA
) ....38.3NC/W
Junction-to-Case Thermal Resistance (B
JC
) ..............3NC/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
(V
PV
= V
PV1
= V
PV2
= 5V, V
EN
= 5V, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Supply Voltage Range
Supply Current
Shutdown Supply Current
Undervoltage-Lockout Threshold
Low
Undervoltage-Lockout Threshold
High
Undervoltage-Lockout Hysteresis
SYNCHRONOUS STEP-DOWN DC-DC CONVERTER
FB Regulation Voltage
Feedback Set-Point Accuracy
pMOS On-Resistance
nMOS On-Resistance
Maximum pMOS Current-Limit
Threshold
V
OUTS
V
OUTS
R
DSON_P
R
DSON_N
I
LIMP1
I
LOAD
= 4A
I
LOAD
= 0A
V
PV1
= 5V, I
LX_
= 0.4A,
LX1 in parallel with LX2
V
PV1
= 5V, I
LX_
= 0.8A,
LX1 in parallel with LX2
LX1 and LX2 shorted together
3.9
-3
-0.5
800
0
+2
34
25
5.1
+3
+3
55
45
6.3
mV
%
mI
mI
A
SYMBOL
V
PV
I
PV
I
SHDN
V
UVLO_L
V
UVLO_H
0.07
CONDITIONS
Normal operation
No load, V
PWM
= 0V
V
EN
= 0V, T
A
= +25
°
C
2.37
2.6
MIN
2.7
12
26
1
TYP
MAX
5.5
45
5
UNITS
V
FA
FA
V
V
V
Maxim Integrated
2
MAX16961
3A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
PV
= V
PV1
= V
PV2
= 5V, V
EN
= 5V, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Maximum Output Current
OUTS Bias Current
LX_ Leakage Current
Minimum On-Time
LX Discharge Resistance
Maximum Short-Circuit Current
OSCILLATOR
Oscillator Frequency
Spread Spectrum
SYNC Input Frequency Range
THERMAL OVERLOAD
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
POWER-GOOD OUTPUT (PG)
PG Overvoltage Threshold
PG Undervoltage Threshold
PG Timeout Period
Undervoltage-/Overvoltage-
Propagation Delay
Output High Leakage Current
PG Output Low Voltage
ENABLE INPUTS (EN)
Input Voltage High
Input Voltage Low
Input Hysteresis
Input Current
Pulldown Resistor
DIGITAL INPUTS (PWM, SYNC AS INPUT)
Input Voltage High
Input Voltage Low
Input Voltage Hysteresis
Pulldown Resistor
50
V
INH
V
INL
50
100
200
1.8
0.4
V
V
mV
kI
V
EN
= high
V
EN
= low
0.1
50
V
INH
V
INL
Input rising
Input falling
0.85
1.0
100
2
200
2.4
0.5
V
V
V
FA
kI
T
A
= +25
°
C
I
SINK
= 3mA
V
PV
= 1.2V, I
SINK
= 100FA
PG
OVTH
PG
UVTH
Percentage of nominal output
Percentage of nominal output
106
90
110
92
16
28
0.2
0.4
0.4
114
94
%
%
ms
Fs
FA
V
+165
15
°C
°C
f
SW
Df/f
f
SYNC
Internally generated
Spread spectrum enabled
50% duty cycle (Note 4)
1.7
2.0
2.2
+6
2.4
2.4
MHz
%
MHz
SYMBOL
I
OUT
I
B_OUTS
I
LX_LEAK
t
ON_MIN
R
LX
V
EN
= 0V, through the OUTS pin
15
CONDITIONS
(V
OUT
+ 0.5V
P
V
PV1
P
5.5V) (Note 3)
Fixed output voltage variants
Adjustable output version
V
PV_
= 5V, LX_ = PGND_ or PV_,
T
A
= +25°C
MIN
3.3
1
-1
-1
60
24
55
7.8
2
5
+1
+1
TYP
MAX
UNITS
A
FA
FA
ns
I
A
Maxim Integrated
3
MAX16961
3A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
PV
= V
PV1
= V
PV2
= 5V, V
EN
= 5V, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Output-Voltage Low
Output-Voltage High
Note
Note
Note
Note
2:
3:
4:
5:
SYMBOL
V
OL
V
OH
I
SINK
= 3mA
V
PV
= 5V, I
SOURCE
= 3mA
4.2
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
V
DIGITAL OUTPUT (SYNC AS OUTPUT)
All limits are 100% production tested at +25°C. Limits over temperature are guaranteed by design.
Calculated value based on an assumed inductor current ripple of 30%.
For SYNC frequency outside (1.7, 2.4) MHz, contact factory.
LX_ has internal clamp diodes to PGND_ and IN_. Applications that forward bias these diodes should take care not to
exceed the IC’s package power dissipation limits.
Typical Operating Characteristics
(V
PV
= V
PV1
= 5V, V
EN
= 5V, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT (PWM)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.0010
0.0100
0.1000
I
LOAD
(A)
1.0000
10.0000
V
OUT
= 1.2V
V
OUT
= 1.8V
V
OUT
= 2.5V
V
IN
= 3.3V
MAX16961 toc01
EFFICIENCY vs. LOAD CURRENT (PWM)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.0010
0.0100
V
OUT
= 1.2V
0.1000
1.0000
10.0000
V
OUT
= 1.8V
V
OUT
= 3.3V
V
IN
= 5V
MAX16961 toc02
EFFICIENCY vs. LOAD CURRENT (SKIP)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
0.001
0.010
0.100
V
IN
= 5V
1.000
10.000
V
OUT
= 1.2V
V
OUT
= 1.8V
V
OUT
= 3.3V
MAX16961 toc03
100
100
100
LOAD CURRENT (A)
LOAD CURRENT (A)
EFFICIENCY vs. LOAD CURRENT (SKIP)
MAX16961 toc04
V
OUT
LOAD REGULATION (PWM)
0
-0.50
REGULATION (%)
-1.00
-1.50
-2.00
-2.50
-3.00
T
A
= +25°C
T
A
= +125°C
0
0.5
1.0
1.5
I
LOAD
(A)
2.0
2.5
3.0
T
A
= -40°C
V
IN
= 5V
V
OUT
= 3.3V
MAX16961 toc05
V
OUT
LOAD REGULATION (SKIP)
0
REGULATION (%)
-1
-2
-3
-4
-5
-6
0
0.5
1.0
1.5
I
LOAD
(A)
2.0
2.5
3.0
T
A
= -40°C
T
A
= +25°C
T
A
= +125°C
V
IN
= 5V
V
OUT
= 3.3V
MAX16961 toc06
100
90
80
EFFICIENCY (%)
0.50
1
70
60
50
40
30
20
10
0
0.0001
0.0010
V
OUT
= 1.8V
V
OUT
= 2.5V
V
OUT
= 1.2V
V
IN
= 3.3V
0.0100
0.1000
1.0000 10.0000
-3.50
-4.00
LOAD CURRENT (A)
Maxim Integrated
4
MAX16961
3A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
V
OUT
vs. V
PV
(PWM)
MAX16961 toc07
I
PV
vs. V
PV
(SKIP)
V
PWM
= 0V
V
EN1
= V
EN2
= V
PV
V
OUT1
= V
OUT2
= 0.8V
T
A
= +125°C
MAX16961 toc08
1.85
1.84
1.83
1.82
V
OUT
(V)
1.81
1.80
1.79
1.78
1.77
1.76
1.75
2.7
3.1
3.5
3.9
4.3
4.7
5.1
T
A
= +125°C
T
A
= +25°C
T
A
= -40°C
I
LOAD
= 0A
40
35
30
I
PV
(µA)
25
20
15
10
T
A
= +25°C
T
A
= -40°C
2.5
3.0
3.5
4.0
V
PV
(V)
4.5
5.0
5.5
5.5
V
PV
(V)
I
PV
vs. TEMPERATURE (SKIP)
MAX16961 toc09
LOAD-TRANSIENT RESPONSE (PWM)
MAX16961 toc10
40
38
36
34
I
PV
(µA)
32
30
28
26
24
22
20
V
PV
= 5V
V
PWM
= 0V
V
EN1
= V
PV
V
OUT
= 0.9V
V
IN
= 3.3V
3.0A
I
LOAD
V
OUT
AC-COUPLED
0.30A
0A
50mV/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
100µs/div
f
SW
vs. TEMPERATURE
2.18
2.16
2.14
SHDN (nA)
f
SW
(MHz)
2.12
2.10
2.08
2.06
2.04
2.02
2.00
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
0.001
2.5
V
IN
= 5V
PWM MODE
MAX16961 toc11
SHDN CURRENT vs. V
PV
MAX16961 toc12
2.20
1000
100
T
A
= +125°C
10
1
0.1
0.01
T
A
= -40°C
3.0
3.5
4.0
V
PV
(V)
4.5
5.0
T
A
= +25°C
5.5
Maxim Integrated
5
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