19-5630; Rev 1; 7/11
TION_KIT
EVALUA BLE
AVAILA
High-Voltage, 2.2MHz, 2A Automotive Step-
Down Converter with Low Operating Current
General Description
The MAX16974 is a 2A, current-mode, step-down con-
verter with an integrated high-side switch. It is designed
to operate with 3.5V to 28V input voltages, while using
only 35FA quiescent current at no load. The switching
frequency is adjustable from 220kHz to 2.2MHz by an
external resistor and can be synchronized to an external
clock. The output voltage is pin selectable to be 5V fixed
or 1V to 10V adjustable. The wide input voltage range
makes the device ideal for automotive and industrial
applications.
The device operates in skip mode for reduced current
consumption in light-load applications. An adjustable
reset threshold helps keep microcontrollers alive down to
their lowest specified input voltage. Protection features
include cycle-by-cycle current limit, overvoltage, and
thermal shutdown with automatic recovery. The device
also features a power-good monitor to ease power-
supply sequencing.
The device operates over the -40°C to +125°C auto-
motive temperature range and is available in a 16-pin
TSSOP-EP package.
Features
S Wide_3.5V_to_28V_Input_Voltage_Range
S 42V_Input_Transient_Tolerance
S 5V_Fixed_or_1V_to_10V_Adjustable_Output_Voltage
S Integrated_2A_Internal_High-Side_Switch
S Adjustable_Switching_Frequency_(220kHz_to_
2.2MHz)
S Operates_Through_Cold_Crank_with_High_Duty_
Cycle
S Frequency_Synchronization_Input
S Internal_Boost_Diode
S 35µA_Skip-Mode_Operating_Current
S 5µA_Typical_Shutdown_Current
S Adjustable_Power-Good_Output_Level_and_Timing
S 3.3V_Logic_Level_to_42V_Compatible_Enable_Input
S Current-Limit,_Thermal-Shutdown,_and_
Overvoltage_Protections
S Automotive_Temperature_Range:_-40°C_to_+125°C
S AEC-Q100_Qualified
MAX16974
Ordering Information
PART
MAX16974AUE/V+
TEMP_RANGE
-40NC to +125NC
PIN-PACKAGE
16 TSSOP-EP*
Applications
Automotive
Industrial
/V Denotes an automotive qualified part.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Typical Application Circuit
V
BAT
C
IN1
47µF
C
IN2
4.7µF
C
IN3
0.1µF
EN
FSYNC
SUP
SUPSW
C
BST
0.1µF
BST
LX
V
OUT
OUT
C
IN4
0.1µF
C
IN5
4.7µF
L1
4.7µH
D1
V
OUT
=
5V AT 2A
C
OUT
22µF
C
COMP1
5600pF
R
COMP
20kI
COMP
C
COMP2
OPEN
R
FOSC
12.1kI
FOSC
BIAS
CRES
GND
MAX16974
RESETI
V
BIAS
FB
RES
V
BIAS
R
RES
10kI
C
BIAS
1µF
C
CRES
100pF
PLACE C
IN2
(4.7µF) AND C
IN3
(0.1µF) NEXT TO SUP.
PLACE C
IN4
(0.1µF) AND C
IN5
(4.7µF) NEXT TO SUPSW.
________________________________________________________________ _Maxim
Integrated Products_
_ 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
High-Voltage, 2.2MHz, 2A Automotive Step-
Down Converter with Low Operating Current
MAX16974
ABSOLUTE_MAXIMUM_RATINGS
SUP, SUPSW, EN to GND .....................................-0.3V to +45V
SUP to SUPSW, LX ...............................................-0.3V to +0.3V
BST to GND ..........................................................-0.3V to +47V
BST to LX ...............................................................-0.3V to +6V
OUT to GND ..........................................................-0.3V to +12V
RESETI, FOSC, COMP, BIAS, FSYNC, CRES,
RES,
FB to GND ..................................................-0.3V to +6V
Output Short-Circuit Duration ....................................Continuous
*As
per JEDEC 51 standard (multilayer board).
Continuous Power Dissipation (T
A
= +70NC)
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)
TSSOP
Junction-to-Ambient Thermal Resistance (q
JA
) ........38.3°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.maxim-ic.com/thermal-tutorial.
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
SUP
= V
SUPSW
= 14V, L1 = 4.7FH, V
EN
= 14V, C
IN
= 10FF, C
OUT
= 22FF, C
BIAS
= 1FF, C
BST
= 0.1FF, C
CRES
= 1nF, R
FOSC
=
12.1kI, T
A
= T
J
= -40NC to +125NC, unless otherwise noted. Typical values are at T
A
= +25NC.)
PARAMETER
Supply Voltage
Supply Current
Shutdown Supply Current
BIAS Regulator Voltage
BIAS Undervoltage Lockout
BIAS Undervoltage Lockout
Hysteresis
Thermal-Shutdown Threshold
OUTPUT_VOLTAGE_(OUT)
Normal operation, V
FB
= V
BIAS
, I
LOAD
= 2A,
T
A
= +25°C
Normal operation, V
FB
= V
BIAS
, I
LOAD
= 2A,
-40°C < T
A
<+125°C
V
OUT
= 5V, V
FB
= V
BIAS
; 400mA < I
LOAD
< 2A
6V < V
SUP
< 28V
I
BST
I
LX
I
SKIP_TH
100% duty cycle, V
BST
- V
LX
= 5V
2.5
4.95
4.9
4.95
5
5
5.05
1
0.02
1.5
3
240
3
3.5
5.05
V
5.1
5.2
V
%
%/V
mA
A
mA
V
BIAS
V
UVBIAS
V
UVBIAS_
HYS
SYMBOL
V
SUP
I
SUP
CONDITIONS
Normal operation
Normal operation, I
LOAD
= 1.5A
Skip mode, no load, V
OUT
= 5V
V
EN
= 0V
V
SUP
= V
SUPSW
= 6V to 42V, V
OUT
> 6V
V
BIAS
rising
MIN
3.5
TYP
2
35
5
MAX
28
3
50
10
5.4
3.25
UNITS
V
mA
FA
FA
V
V
mV
NC
4.9
2.85
5.1
3.05
350
175
Output Voltage
V
OUT
Skip-Mode Output Voltage
Load Regulation
Line Regulation
BST Input Current
LX Current Limit
Skip-Mode Current Threshold
V
OUT_SKIP
No load, V
FB
= V
BIAS
(Note 2)
2_ _ _______________________________________________________________________________________
High-Voltage, 2.2MHz, 2A Automotive Step-
Down Converter with Low Operating Current
ELECTRICAL_CHARACTERISTICS_(continued)
(V
SUP
= V
SUPSW
= 14V, L1 = 4.7FH, V
EN
= 14V, C
IN
= 10FF, C
OUT
= 22FF, C
BIAS
= 1FF, C
BST
= 0.1FF, C
CRES
= 1nF, R
FOSC
=
12.1kI, T
A
= T
J
= -40NC to +125NC, unless otherwise noted. Typical values are at T
A
= +25NC.)
PARAMETER
Power-Switch On-Resistance
LX Leakage Current
SYMBOL
R
ON
I
LX,LEAK
CONDITIONS
R
ON
measured between SUPSW and LX,
I
LX
= 500mA
V
SUP
= 28V, V
LX
= 0V, T
A
= +25°C
V
SUP
= 28V, V
LX
= 0V, T
A
= +125°C
0.04
20
FB connected to an external resistive divider,
T
A
= +25°C
FB connected to an external resistive divider,
-40°C < T
A
< +125°C
6V < V
SUP
< 28V
V
FB
= 1V, V
BIAS
= 5V
0.99
0.985
1.0
1.0
0.02
1000
120
92
R
FOSC
= 120kI
R
FOSC
= 12.1kI
190
2.00
260
2.20
310
2.48
1.01
V
1.015
%/V
FS
ns
%
kHz
MHz
MIN
TYP
185
MAX
400
1
UNITS
mI
FA
MAX16974
TRANSCONDUCTANCE_AMPLIFIER_(COMP)
FB Input Current
I
FB
nA
FB Regulation Voltage
V
FB
FB Line Regulation
Transconductance (from FB to
COMP)
Minimum On-Time
Cold-Crank Event Duty Cycle
OSCILLATOR_FREQUENCY
Oscillator Frequency
DV
LINE
g
m,EA
t
MIN,ON
DC
CC
EXTERNAL_CLOCK_INPUT_(FSYNC)
External Input Clock Acquisition
Time
External Input Clock High
Threshold
FSYNC Pulldown Resistance
Soft-Start Time
ENABLE_INPUT_(EN)
Enable-On Threshold Voltage Low
Enable-On Threshold Voltage High
Enable Threshold Voltage
Hysteresis
Enable Input Current
RESET
Reset Internal Switching Level
RESETI Threshold Voltage
CRES Threshold Voltage
CRES Threshold Hysteresis
RESETI Input Current
V
TH_RISING
V
FB
rising, V
RESETI
= 0V
V
TH_FALLING
V
FB
falling, V
RESETI
= 0V
V
RESETI_LO
V
RESETI
falling
V
CRES_HI
V
CRES_HYS
I
RESET
V
RESETI
= 0V
V
CRES
rising
0.88
0.83
1.13
1.1
0.90
0.85
1.2
1.25
0.04
0.02
0.92
0.87
1.27
1.45
V
V
V
V
FA
V
EN_LO
V
EN_HI
V
EN,HYS
I
EN
2.2
0.35
0.5
0.7
V
V
V
FA
t
FSYNC
V
FSYNC_HI
V
FSYNC
rising
1.5
0.5
510
f
SW
= 220kHz
f
SW
= 2.2MHz
9.3
0.93
4
Cycles
V
V
kI
ms
External Input Clock Low Threshold V
FSYNC_LO
V
FSYNC
falling
I
FSYNC
t
SS
________________________________________________________________________________________ _ 3
High-Voltage, 2.2MHz, 2A Automotive Step-
Down Converter with Low Operating Current
MAX16974
ELECTRICAL_CHARACTERISTICS_(continued)
(V
SUP
= V
SUPSW
= 14V, L1 = 4.7FH, V
EN
= 14V, C
IN
= 10FF, C
OUT
= 22FF, C
BIAS
= 1FF, C
BST
= 0.1FF, C
CRES
= 1nF, R
FOSC
=
12.1kI, T
A
= T
J
= -40NC to +125NC, unless otherwise noted. Typical values are at T
A
= +25NC.)
PARAMETER
CRES Source Current
CRES Pulldown Current
RES
Sink Current
RES
Leakage Current (Open-
Drain Output)
Reset Debounce Time
t
RES_DEB
SYMBOL
I
CRES
I
CRES_PD
CONDITIONS
V
OUT
in regulation
V
OUT
out of regulation
V
RES
pulls low, V
RES
> 0.4V
V
OUT
in regulation, T
A
= +25NC
V
RESETI
falling
25
MIN
9.5
1
1
1
TYP
10
MAX
10.5
UNITS
FA
mA
mA
FA
Fs
Note_2:
Guaranteed by design; not production tested.
Typical Operating Characteristics
(V
SUP
= V
SUPSW
= 14V, V
OUT
= 5V, FSYNC = GND, f
OSC
= 400kHz, T
A
= +25NC, unless otherwise noted. See Figure 1.)
EFFICIENCY vs. I
LOAD
(SKIP MODE)
MAX16974 toc01
EFFICIENCY vs. I
LOAD
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
I
LOAD
(A)
1
10
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX16974 toc02
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
V
SUP
= 14V
5V/400kHz
V
SUP
= 14V
90
80
SUPPLY CURRENT (µA)
70
60
50
40
30
20
10
0
6
5V/400kHz
5V/2.2MHz
5V/2.2MHz
5V/2.2MHz
5V/400kHz
0
0.00001
0.0001
0.001
I
LOAD
(C)
0.01
0.1
8 10 12 14 16 18 20 22 24 26 28
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
4
6
MAX16974 toc04
STARTUP INTO HEAVY LOAD
MAX16974 toc05
5V/div
V
SUP
0V
5V/div
SHUTDOWN CURRENT (µA)
T
A
= +125°C
T
A
= +25°C
V
OUT
0V
2A/div
T
A
= -40°C
8 10 12 14 16 18 20 22 24 26 28
INPUT VOLTAGE (V)
I
LOAD
10ms/div
SF = 400kHz
0A
4_ _ _______________________________________________________________________________________
MAX16974 toc03
100
100
100
High-Voltage, 2.2MHz, 2A Automotive Step-
Down Converter with Low Operating Current
Typical Operating Characteristics (continued)
(V
SUP
= V
SUPSW
= 14V, V
OUT
= 5V, FSYNC = GND, f
OSC
= 400kHz, T
A
= +25NC, unless otherwise noted. See Figure 1.)
MAX16974
LOAD TRANSIENT
MAX16974 toc06
UNDERVOLTAGE PULSE
MAX16974 toc07
200mV/div
V
OUT
0V
V
SUP
5V/div
0V
SF = 400kHz
V
OUT
AC-
COUPLED
V
OUT
1A/div
0A
V
RES
20ms/div
SF = 2.2MHz
5V/div
0V
5V/div
0V
I
LOAD
RESET TIMEOUT PERIOD vs. C
RES
MAX16974 toc08
SWITCHING FREQUENCY
vs. TEMPERATURE
490
SWITCHING FREQUENCY (kHz)
480
470
460
450
440
430
420
410
400
90
RESET TIMEOUT PERIOD (ms)
80
70
60
50
40
30
20
10
0
0
V
OUT
= 5V
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
C
RES
(µF)
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
LOAD DUMP TEST (5V/2.2MHz)
MAX16974 toc10
SHORT-CIRCUIT RESPONSE
MAX16974 toc11
2.2MHz
V
SUP
20V/div
0
V
OUT
5V/div
0
V
RES
5V/div
0
100ms/div
V
OUT
I
LX
5A/div
0A
5V/div
0V
5V/div
0V
2ms/div
V
RES
________________________________________________________________________________________ _ 5
MAX16974 toc09
100
500
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