MAXIM MAX16922ATP

19-5039; Rev 0; 10/09
KIT
ATION
EVALU
E
L
B
AVAILA
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
Features
o 1.2A High-Efficiency 2.2MHz DC-DC Converter
3.7V to 28V Operating Supply Voltage
45V Load-Dump Protection
Output Voltage: 3.0V to 5.5V
o 600mA High-Efficiency 2.2MHz DC-DC Converter
2.7V to 5.5V Supply Voltage
Output Voltage: 1.0V to 3.9V
180° Out-of-Phase Operation
Forced-PWM and Auto-PWM Modes
o LDO Linear Regulators
OUT3: 1.0V to 4.15V at 300mA
OUT4: 1.0V to 4.15V at 300mA
Separate Inputs for Increased Efficiency
o Enable Input
o RESET Output Monitoring on OUT1 and OUT2
o Overtemperature and Short-Circuit Protection
o Available in
5mm x 5mm x 0.8mm, 20-Pin TQFN-EP
4.5mm x 6.5mm, 20-Pin TSSOP-EP
The MAX16922 power-management integrated circuit
(PMIC) is designed for medium power-level automotive
applications and integrates multiple supplies in a small
footprint. The device includes one high-voltage stepdown converter (OUT1) and three low-voltage cascaded DC-DC converters (OUT2, OUT3, OUT4). OUT1 and
OUT2 are step-down DC-DC converters, and OUT3/
OUT4 are linear regulators. The device also includes a
reset output (RESET) and a high-voltage-compatible
enable input (EN).
The 1.2A output high-efficiency, step-down DC-DC converter (OUT1) operates from a voltage up to 28V continuous and is protected from load-dump transients up to
45V. The 600mA output high-efficiency step-down DCDC converter (OUT2) runs from a voltage up to 5.5V.
The two 300mA LDO linear regulators offer low dropout
of only 130mV (typ). The power-good RESET output
provides voltage monitoring for OUT1 and OUT2.
OUT1 and OUT2 use fast 2.2MHz PWM switching and
small external components. The high-voltage converter
(OUT1) enters skip mode automatically under light
loads to prevent an overvoltage condition from occurring at the output. The low-voltage synchronous DC-DC
converter (OUT2) can operate in forced-PWM mode to
prevent any AM band interference or high-efficiency
auto-PWM mode.
The MAX16922 includes overtemperature shutdown
and overcurrent limiting. All devices are designed to
operate from -40°C to +125°C ambient temperature.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX16922ATP_ /V+*
-40°C to +125°C
20 TQFN-EP**
MAX16922AUP_ /V+*
-40°C to +125°C
20 TSSOP-EP**
*Insert the desired suffix letters (from the Selector Guide) into
the blank “_” to complete the part number.
+Denotes lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
**EP = Exposed pad.
Typical Operating Circuit
VPV1
PV1
4.7µF
OUTS2
EN
PWM
VOUT1
2.2µH
LX2
VOUT2
10µF
PGND2
PV3
PV2
4.7µF
MAX16922
VOUT3
4.7µF
VOUT2
4.7µF
BST
0.1µF
OUT3
GND1
GND3
4.7µH
LX1
OUTS1
PV4
VOUT1
10µF
4.7µF
VOUT4
4.7µF
1µF
GND
GND2
VOUT1
LSUP
OUT4
EP
20kΩ
RESET
________________________________________________________________ Maxim Integrated Products
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.
1
MAX16922
General Description
MAX16922
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
ABSOLUTE MAXIMUM RATINGS
PV1, EN to GND .....................................................-0.3V to +45V
LX1 to GND.................................................-0.5V to (PV1 + 0.3V)
LX2 to GND.................................................-0.5V to (PV2 + 0.3V)
BST to LX1.............................................................-0.3V to +6.0V
PV2, PV3, PV4, OUTS1, PWM, RESET to GND_....-0.3V to +6.0V
OUTS2 .......................................................-0.3V to (PV2 + 0.3V)
OUT3 .........................................................-0.3V to (PV3 + 0.3V)
OUT4 .........................................................-0.3V to (PV4 + 0.3V)
LX1 RMS Current .................................................................2.0A
LX2 RMS Current .................................................................1.2A
PGND2 to GND_....................................................-0.3V to +0.3V
LSUP to GND............................................................-0.3V to +6V
OUTS_, OUT_ Output Short-Circuit Duration .............Continuous
Continuous Power Dissipation (TA = +70°C)
20-Pin TQFN-EP (derate 31.3 mW/°C above +70°C)....... 2500mW
20-Pin TSSOP-EP (derate 26.5 mW/°C above +70°C)..... 2122mW
Junction-to-Case Thermal Resistance (θJC) (Note 1)
20-Pin TQFN-EP .......................................................... 2.7°C/W
20-Pin TSSOP-EP ........................................................... 2°C/W
Junction-to-Ambient Thermal Resistance (θJA) (Note 1)
20-Pin TQFN-EP ........................................................... 32°C/W
20-Pin TSSOP-EP ..................................................... 37.7°C/W
ESDHB (all pins) ...................................................................±2kV
ESDMM (all pins) ................................................................±200V
ESDCDM (corner pins) .......................................................±750V
ESDCDM (other pins)..........................................................±500V
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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 http://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
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at
TA = +25°C under normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OUT1—SYNCHRONOUS STEP-DOWN DC-DC CONVERTER
Supply-Voltage Range
PV1 Undervoltage Lockout
BST Refresh Load Enable
VPV1
(Note 3)
VUVLO,R
PV1 rising
VUVLO,F
PV1 falling
VBRLE
3.7
45
3.7
2.9
PV1 falling (option enabled)
BST Refresh Load Hysteresis
LSUP Regulator Voltage
VLSUP
28
Operation < 500ms
6V ≤ VPV1 ≤ 28V
4.75
4.0
3.3
5.7
V
V
5.0
5.25
IPV1
EN = low
PWM Switching Frequency
fSW
Internally generated
2.0
Duty cycle = 20% to 90%;
ILOAD = 300mA to 1.2A
-3
+3
SKIP mode (Note 4)
-2
+4
VOUT1
DMOS On-Resistance
5
VPV1 = 4V, VBST = 9V, ILX1 = 0.2A
Current-Limit Threshold
1.4
Soft-Start Ramp Time
Maximum Output Current
Maximum Duty Cycle
DCMAX
Minimum Duty Cycle
DCMIN
2
(VOUT1 + 1.0V) ≤ VPV1 ≤ 28V
VPV1 = 12V, LX1 = GND or VPV1;
TA = -40°C to +85°C
LX1 Leakage Current
OUTS1 Discharge Resistance
2.2
2.4
300
700
2.1
1.2
V
µA
1.75
2.2
IOUT1
V
0.25
Supply Current
Voltage Accuracy
V
MHz
%
mΩ
A
ms
A
±1
µA
97
%
fSW = 2.2MHz
20
%
EN = low (or optionally EN = high and
VPV1 < 5.7V)
70
Ω
_______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at
TA = +25°C under normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
2.4
MHz
OUT2—SYNCHRONOUS STEP-DOWN DC-DC CONVERTER
Supply-Voltage Range
VPV2
Fully operational
2.7
PWM Switching Frequency
fSW
Internally generated
2.0
Duty cycle = 20% to 90%;
ILOAD = 1mA to 600mA, PWM = high
-3
+3
%
SKIP mode (Note 4)
-2
+4
%
Voltage Accuracy
VOUT2
2.2
pMOS On-Resistance
VPV2 = 5.0V, ILX2 = 0.2A
150
250
mΩ
nMOS On-Resistance
VPV2 = 5.0V, ILX2 = 0.2A
200
350
mΩ
0.9
1.05
A
pMOS Current-Limit Threshold
0.75
nMOS Zero-Crossing Threshold
50
mA
Soft-Start Ramp Time
1.5
ms
Maximum Output Current
IOUT2
VOUT2 + 0.5V ≤ VPV2 ≤ 5.5V
LX2 Leakage Current
VPV2 = 6V, LX2 = PGND2 or VPV2;
TA = -40°C to +85°C
Duty-Cycle Range
Forced-PWM mode only, minimum duty
cycle in skip mode is 0% (Note 4)
OUTS2 Discharge Resistance
EN = 0V
600
mA
±1
15
µA
100
%
Ω
70
OUT3—LDO REGULATOR
Input Voltage
VPV3
Voltage Accuracy
VOUT3
VOUT3 + 0.4V ≤ VPV3 ≤ 5.5V, ILOAD = 1mA
1.7
5.5
V
-2
+2
%
Load Regulation
ILOAD = 0 to 300mA
-0.2
Dropout Voltage
VPV3 = 1.8V, ILOAD = 250mA (Note 4)
130
Current Limit
%
320
mV
450
mA
Power-Supply Rejection Ratio
IOUT3 = 30mA, f = 1kHz
57
dB
Shutdown Output Resistance
EN = low
1
kΩ
OUT4—LDO REGULATOR
Input Voltage
VPV4
Voltage Accuracy
VOUT4
1.7
(VOUT4 + 0.4V) ≤ VPV4 ≤ 5.5V, ILOAD = 1mA
-2
Load Regulation
ILOAD = 0 to 300mA
-0.2
Dropout Voltage
VPV4 = 1.8V, ILOAD = 250mA (Note 4)
130
Current Limit
5.5
V
+2
%
%
320
mV
450
mA
Power-Supply Rejection Ratio
IOUT4 = 30mA, f = 1kHz
57
dB
Shutdown Output Resistance
EN = low
1
kΩ
175
°C
15
°C
THERMAL OVERLOAD
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
(Note 4)
150
_______________________________________________________________________________________
3
MAX16922
ELECTRICAL CHARACTERISTICS (continued)
MAX16922
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
ELECTRICAL CHARACTERISTICS (continued)
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at
TA = +25°C under normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RESET
OUT1 OV Threshold
OUT1 Reset Threshold
OUT2 Reset Threshold
Reset Timeout Period
110
85
90
95
Reset option 2 (see the Selector Guide)
75
80
85
Percentage of nominal output
85
90
95
Reset timeout option 1 (see the Selector
Guide)
14.9
Reset timeout option 2 (see the Selector
Guide)
1.9
%
%
ms
Output-High Leakage Current
Output Low Level
%
Reset option 1 (see the Selector Guide)
1
Sinking -3mA
µA
0.4
UV Propagation Time
28
V
µs
EN LOGIC INPUT
EN Threshold Voltage
EN rising
1.4
EN Threshold Hysteresis
Input Current
VEN = 5V
1.8
2.2
V
0.2
V
0.5
µA
PWM LOGIC INPUT
Input High Level
PWM rising
Input Low Level
PWM falling
Logic-Input Current
0 ≤ VPWM ≤ 5.5V
1.8
V
0.4
1
Note 2: All units are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Note 3: Once PVI exceeds undervoltage-lockout rising threshold 4.0V and the device is in regulation.
Note 4: Guaranteed by design. Not product tested.
4
_______________________________________________________________________________________
V
µA
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
OUT1 EFFICIENCY vs. LOAD CURRENT
50
40
TA = +25°C
50
40
30
20
20
10
10
LOAD CURRENT (A)
LOAD CURRENT (A)
SUPPLY CURRENT vs. TEMPERATURE
NORMALIZED OUT1 VOLTAGE
vs. LOAD CURRENT
1.3
1.2
1.1
0.5
IOUT1 = 1A
5.15
1.0
0.6
5.10
0.5
0
-0.5
5.05
5.00
4.95
-1.0
4.90
-1.5
4.85
4.80
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
TEMPERATURE (°C)
IPV1 (A)
6
9
12
15
18
VPV1 (V)
POWER-UP/DOWN AT
THERMAL SHUTDOWN
POWER-UP ENABLE TURNING ON
1ms/div
0.4
OUT1 VOLTAGE vs. VPV1
-40 -25 -10 5 20 35 50 65 80 95 110 125
MAX16922 toc07
0.3
5.20
MAX16922 toc05
1.5
0.2
LOAD CURRENT (A)
-2.0
1.0
70
0.1
OUT1 VOLTAGE (V)
1.4
2.0
NORMALIZED OUT1 VOLTAGE (%)
MAX16922 toc04
1.5
TA = +25°C
50
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
1.6
TA = +125°C
80
PV2 = 5V
OUT2 = 2.7V
0
NO LOAD
PWM = GND
MAX16922 toc03
90
60
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
1.8
1.7
TA = +125°C
60
30
0
SUPPLY CURRENT (mA)
70
MAX16922 toc06
PV1 = 13.5V
PV1 = 18V
TA = -40°C
80
PV1 = 8V
70
EFFICIENCY (%)
EFFICIENCY (%)
80
PV1 = 13.5V
90
OUT2 EFFICIENCY vs. LOAD CURRENT
100
EFFICIENCY (%)
MAX16922 toc01
90
60
100
MAX16922 toc02
OUT1 EFFICIENCY vs. LOAD CURRENT
100
EN
10V/div
OUT1
5V/div
MAX16922 toc08
RESET
5V/div
OUT1
5V/div
OUT2
2V/div
OUT2
2V/div
OUT3
2V/div
OUT3
2V/div
OUT4
1V/div
OUT4
1V/div
2ms/div
_______________________________________________________________________________________
5
MAX16922
Typical Operating Characteristics
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specified.)
Typical Operating Characteristics (continued)
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specified.)
1.2
0.8
0.4
OUT1
0.5
0.4
OUT2
0.3
IOUT1 = 1.2A
DROPOUT VOLTAGE (V)
DROPOUT VOLTAGE (V)
0.6
1.6
1.2
MAX16922 toc10
0.7
MAX16922 toc09
2.0
OUT1 DROPOUT VOLTAGE
vs. TEMPERATURE
DROPOUT VOLTAGE vs. LOAD CURRENT
0.2
MAX16922 toc11
SWITCHING FREQUENCY
vs. LOAD CURRENT
SWITCHING FREQUENCY (MHz)
1.0
0.8
0.6
0.1
OUT3
0
0.4
0
0
200
400
600
800
1000
1200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
-40 -25 -10 5 20 35 50 65 80 95 110 125
LOAD CURRENT (A)
TEMPERATURE (°C)
LOAD CURRENT (mA)
OUT2 DROPOUT VOLTAGE
vs. TEMPERATURE
OUT1 LOAD TRANSITION
IOUT2 = 600mA
0.6
MAX16922 toc12
MAX16922 toc13
0.7
DROPOUT VOLTAGE (V)
MAX16922
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
IOUT1
500mA/div
0.5
0.4
VOUT1
AC-COUPLED
50mV/div
0.3
0.2
0.1
0
20ms/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
OUT1 LINE TRANSIENT
OUT2 LOAD TRANSIENT
MAX16922 toc15
MAX16922 toc14
IOUT2
200mA/div
PV1
5V/div
VOUT2
AC-COUPLED
20mV/div
20ms/div
6
OUT1
AC-COUPLED
20mV/div
4ms/div
_______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
SWITCHING FREQUENCY
vs. TEMPERATURE
-30
2.22
-40
2.20
2.18
-60
-70
2.14
-80
2.12
-90
2.10
-100
-40 -25 -10 5 20 35 50 65 80 95 110 125
10
100
1k
10k
OUT3 OUTPUT-NOISE DENSITY
vs. FREQUENCY
OUT4 OUTPUT-NOISE DENSITY
vs. FREQUENCY
2800
2400
2000
1600
1200
800
RL = 100Ω
1800
OUTPUT-NOISE DENSITY (nV/ Hz)
3200
2000
100k
MAX16922 toc19
FREQUENCY (Hz)
MAX16922 toc18
OUTPUT-NOISE DENSITY (nV/ Hz)
OUT3
TEMPERATURE (°C)
RL = 100Ω
3600
OUT4
-50
2.16
4000
LOAD CURRENT = 100mA
100mVP-P RIPPLE
-20
2.24
PSRR (dB)
SWITCHING FREQUENCY (MHz)
2.26
0
-10
MAX16922 toc17
PWM = OUT1
2.28
MAX16922 toc16
2.30
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
1600
1400
1200
1000
800
600
400
200
400
0
0
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
_______________________________________________________________________________________
7
MAX16922
Typical Operating Characteristics (continued)
(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specified.)
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
MAX16922
Functional Diagram
VOUT1
LINEAR
REGULATOR
LSUP
20kΩ
1µF
BST
RESET
PV1
POR
GENERATION
VPV1
4.7µF
GND1
PV3
VOUT1
STEP-DOWN
PWM
OUT1
LDO REG 1: 300mA
4.7µF
PWM
VOUT1
3.0V TO 5.5V
1.2A
10µF
EN
EN
OUTS1
OUT3
4.7µF
4.7µH
LX1
1.0V TO 4.15V
GND2
MAX16922
PWM
MODE
SELECT
PV2
4.7µF
PV4
VOUT2
LDO REG 2: 300mA
STEP-DOWN
PWM
OUT2
4.7µF
OUT4
PGND2
PWM
EN
EN
8
VOUT2
10µF
1.0V TO 4.15V
4.7µF
100kΩ
2.2µH
1.0V TO 3.9V
600mA
EN
VOUT4
LX2
OUTS2
EP
_______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
TOP VIEW
PV2
11
OUT3
PV3
12
13
GND2
14
15
OUT4
TOP VIEW
PV4
16
10
LX2
LSUP
17
9
PGND2
RESET
18
8
OUTS2
GND1
19
7
GND
EN
20
6
PWM
*EP = EXPOSED PAD.
MAX16922
*EP
20
RESET
EN
2
19
LSUP
BST
3
18
PV4
PV1
4
17
OUT4
LX1
5
16
GND2
15
OUT3
MAX16922
14
PV3
8
13
PV2
9
12
LX2
10
11
PGND2
5
7
PWM
GND
OUTS1
OUTS1
4
6
3
GND3
LX1
2
PV1
1
GND3
1
BST
+
+
GND1
OUTS2
THIN QFN
*EP
TSSOP
Pin Description
PIN
NAME
FUNCTION
TQFN
TSSOP
1
3
BST
Bootstrap Capacitor Input. Connect a 0.1µF ceramic capacitor from BST to LX1.
2
4
PV1
OUT1 Supply Input. Connect a 4.7µF or larger ceramic capacitor from PV1 to PGND.
3
5
LX1
Inductor Connection for OUT1. Connect a 4.7µH inductor between LX1 and OUTS1, and a
Schottky diode between LX1 (cathode) and the power-ground plane (anode) as shown in the
Functional Diagram.
4
6
GND3
Ground. Connect GND, GND1, GND2, and GND3 together.
5
7
OUTS1
OUT1 Voltage-Sensing Input. Connect OUTS1 directly to the OUT1 output voltage and
bypass to power-ground plane with a minimum total capacitance of 15µF. The total
capacitance can include input bypass capacitors cascaded from OUT1, discharged by a
70Ω resistance between OUTS1 and GND3 when disabled.
6
8
PWM
PWM Control Input. Connect PWM to OUTS1 to force LX2 to switch every cycle. Connect
PWM to high for forced-PWM operation on OUT2. Connect low for auto-PWM operation to
improve efficiency at light loads.
7
9
GND
Ground. Connect GND, GND1, GND2, and GND3 together.
_______________________________________________________________________________________
9
MAX16922
Pin Configurations
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
MAX16922
Pin Description (continued)
PIN
TQFN
NAME
FUNCTION
8
10
OUTS2
OUT2 Voltage Sense Input. Connect OUTS2 directly to the OUT2 output voltage and
bypass to PGND2 with a minimum total capacitance of 10µF. The total capacitance can
include input bypass capacitors cascaded from OUT2, discharged by a 70Ω resistance
between OUTS2 and PGND2 when disabled.
9
11
PGND2
Power Ground for BUCK 2. Connect PGND2 and GND_ together near the device.
10
12
LX2
Inductor Connection for OUT2. Connect a 2.2µH inductor between LX2 and OUT2 as shown
in the Functional Diagram.
11
13
PV2
OUT2 Supply Input. Connect a 4.7µF or larger ceramic capacitor from PV2 to ground.
12
14
PV3
Linear-Regulator Power Input for OUT3. Bypass PV3 to GND with a minimum 2.2µF ceramic
capacitor.
13
15
OUT3
Linear-Regulator 1 Output. Bypass OUT3 to GND with a minimum 2.2µF ceramic capacitor
internally discharged by a 1kΩ resistance when disabled.
14
16
GND2
Ground. Connect GND, GND1, GND2, and GND3 together.
15
17
OUT4
Linear-Regulator 2 Output. Bypass OUT4 to GND with a minimum 2.2µF ceramic capacitor.
Internally discharged by a 1kΩ resistance when disabled.
16
18
PV4
Linear-Regulator Power Input for OUT4. Bypass PV4 to GND with a minimum 2.2µF ceramic
capacitor.
17
19
LSUP
5V Logic Supply to Provide Power to Internal Circuitry. Bypass LSUP to GND1 with a 1µF
ceramic capacitor.
18
20
RESET
Open-Drain Reset Output for the Input Monitoring OUT1 and OUT2. External pullup
required.
19
1
GND1
Ground. Connect GND, GND1, GND2, and GND3 together.
20
2
EN
Active-High Enable Input. Connect EN to PV1 or a logic-high voltage to turn on all
regulators. Pull EN input low to place the regulators in shutdown.
EP
Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground
does not remove the requirement for proper ground connections to PGND2 and GND_. The
exposed pad is attached with epoxy to the substrate of the die, making it an excellent path
to remove heat from the device.
—
10
TSSOP
—
______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
The MAX16922 PMIC is designed for medium power
level automotive applications requiring multiple supplies in a small footprint. As shown in the Typical
Applications Circuit , the MAX16922 integrates one
high-voltage power supply and three low-voltage cascaded power supplies. OUT1 and OUT2 are step-down
DC-DC converters, and OUT3 and OUT4 are linear regulators. The device also includes a reset output
(RESET) and a high-voltage compatible enable input
(EN). The operating input voltage range is from 3.5V to
28V and tolerant of transient voltages up to 45V.
OUT1 Step-Down DC-DC Regulator
Step-Down Regulator Architecture
OUT1 is a high-input voltage, high-efficiency 2.2MHz
PWM current-mode step-down DC-DC converter that
delivers up to 1.2A. OUT1 has an internal high-side nchannel switch and uses a low forward-drop freewheeling diode for rectification. Under normal
operating conditions, OUT1 is fixed frequency to prevent unwanted AM radio interference. However, under
light loads and high-input voltage, the step-down regulator skips cycles to maintain regulation. The output
voltage is factory selectable from 3.0V to 5.5V in 50mV
increments.
Soft-Start
When initially powered up or enabled with EN, the
OUT1 step-down regulator soft-starts by gradually
ramping up the output voltage for approximately 2.2ms.
This reduces inrush current during startup. During softstart the full output current is available. Before a softstart sequence begins, the outputs of both DC-DC
regulators discharge below 1.25V through an internal
resistor. See the startup waveforms in the Typical
Operating Characteristics section.
Current Limit
The MAX16922 limits the peak inductor current
sourced by the n-channel MOSFET. When the peak
current limit is reached, the internal n-channel MOSFET
turns off for the remainder of the cycle. If the current
limit is exceeded for 16 consecutive cycles and the
output voltage is less than 1.25V, the n-channel MOSFET is turned off for 256 clock cycles to allow the
inductor current to discharge and then initiate a softstart sequence for all four outputs.
Dropout
The high-voltage, step-down converter (OUT1) of the
MAX16922 is designed to operate near 100% dutycycle. When the input voltage is close to the output
voltage, the device tries to maintain the high-side
switch on with 100% duty cycle. However, to maintain
proper gate charge, the high-side switch must be
turned off periodically so the LX pin can go to ground
and charge the BST capacitor. As the input voltage
approaches the output voltage, the effective duty cycle
of the n-channel MOSFET approaches 96.9%. Every
4th cycle is limited to a maximum duty cycle of 87.5%
(recharge period is approximately 56ns) while the
remaining cycles can go to 100% duty cycle. As a
result, when the MAX16922 is in dropout, the switching
frequency is reduced by a factor of 4.
During dropout conditions under light load, the load
current may not be sufficient to enable the LX pin to
reach ground during the recharge period. To ensure
the LX pin is pulled to ground and proper BST capacitor recharge occurs, an internal load is applied to
OUTS1 when PV1 falls below approximately 5.8V. This
load is approximately 70Ω and is connected between
OUTS1 and GND3 through an internal switch.
OUT2 Step-Down DC-DC Regulator
Step-Down Regulator Architecture
OUT2 is a low-input voltage, high-efficiency 2.2MHz
PWM current-mode step-down DC-DC converter that
outputs up to 600mA. OUT2 has an internal high-side
p-channel switch, and low-side n-channel switch for
synchronous rectification. The DC-DC regulator supports auto-PWM operation so that under light loads the
device automatically enters high-efficiency skip mode.
The auto-PWM mode can be disabled by connecting
the PWM input to OUTS1. The output voltage is factory
selectable from 1.0V to 3.9V in 50mV increments.
Soft-Start
OUT2 enters soft-start when OUT1 finishes its soft-start
sequence to prevent high startup current from exceeding the maximum capability of OUT1. The step-down
regulator executes a soft-start by gradually ramping up
the output voltage for approximately 1.5ms. This
reduces inrush current during startup. During soft-start,
the full output current is available. The soft-start
sequence on OUT2 begins after the soft-start sequence
is completed on OUT1. See the startup waveforms in
the Typical Operating Characteristics section.
______________________________________________________________________________________
11
MAX16922
Detailed Description
MAX16922
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
Current Limit
The MAX16922 limits the peak inductor current sourced
by the p-channel MOSFET. When the peak current limit
is reached, the internal p-channel MOSFET turns off for
the remainder of the cycle. If the current limit is exceeded for 16 consecutive cycles, and the output voltage is
less than 1.25V, the p-channel MOSFET is turned off
and enters output discharge mode for 256 clock
cycles, allowing the inductor current and output voltage
to discharge. Once completed, a soft-start sequence is
initiated on OUT2.
Dropout
As the input voltage approaches the output voltage, the
duty cycle of the p-channel MOSFET reaches 100%. In
this state, the p-channel MOSFET is turned on constantly (not switching), and the dropout voltage is the voltage drop due to the output current across the
on-resistance of the internal p-channel MOSFET (RPCH)
and the inductor’s DC resistance (RL):
VDO = ILOAD (RPCH + RL)
PWM
The MAX16922 operates in either auto-PWM or forcedPWM modes. At light load, auto-PWM switches only as
needed to supply the load to improve light-load efficiency
of the step-down converter. At higher load currents
(~160mA), the step-down converter transitions to fixed
2.2MHz switching frequency. Forced PWM always operates with a constant 2.2MHz switching frequency regardless of the load. Connect PWM high for forced-PWM
applications or low for auto-PWM applications.
LDO Linear Regulators
The MAX16922 contains two low-dropout linear regulators (LDOs), OUT3 and OUT4. The LDO output voltages
are factory preset, and each LDO supplies loads up to
300mA. The LDOs include an internal reference, error
amplifier, p-channel pass transistor, and internal voltage-dividers. Each error amplifier compares the reference voltage to the output voltage (divided by the
internal voltage-divider) and amplifies the difference. If
the divided feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled lower,
allowing more current to pass to the outputs and
increasing the output voltage. If the divided feedback
voltage is too high, the pass-transistor gate is pulled up,
allowing less current to pass to the output. Each output
voltage is factory selectable from 1.0V to 4.15V in 50mV
increments. If not using one of the LDO outputs, then tie
the associated input power pin (PV_) to ground.
12
Input Supply and Undervoltage Lockout
An undervoltage-lockout circuit turns off the LDO
regulators when the input supply voltage is too low to
guarantee proper operation. When PV3 falls below
1.25V (typ), OUT3 powers down. When PV4 falls below
1.5V (typ), OUT4 powers down.
Soft-Start
OUT3 enters soft-start when PV3 exceeds 1.25V, and
OUT4 enters soft-start when PV4 exceeds 1.5V. This
staggers the surge current during startup to prevent
excess current draw from OUT1 or OUT2 that could
trigger an overcurrent shutdown. The soft-start time for
each LDO is 0.1ms (typ). See the startup waveforms in
the Typical Operating Characteristics section.
Current Limit
The OUT3 and OUT4 output current is limited to 450mA
(typ). If the output current exceeds the current limit, the
corresponding LDO output voltage drops out of regulation. Excess power dissipation in the device can cause
the device to turn off due to thermal shutdown.
Dropout
The dropout voltage for the linear regulators is 320mV
(max) at 250mA load. To avoid dropout, make sure the
input supply voltage corresponding to OUT3 and OUT4
is greater than the corresponding output voltage plus
the dropout voltage based on the application output
current requirements.
LSUP Linear Regulator
LSUP is the output of a 5V linear regulator that powers
MAX16922 internal circuitry. LSUP is internally powered
from PV1 and automatically powers up when EN is high
and PV1 exceeds approximately 3.7V. LSUP automatically powers down when EN is taken low. Bypass LSUP
to GND with a 1µF ceramic capacitor. LSUP remains on
even during a thermal fault.
Thermal-Overload Protection
Thermal-overload protection limits the total power dissipation in the MAX16922. Thermal-protection circuits
monitor the die temperature. If the die temperature
exceeds +175°C, the device shuts down, allowing it to
cool. Once the device has cooled by 15°C, the device
is enabled again. This results in a pulsed output during
continuous thermal-overload conditions. The thermaloverload protection protects the MAX16922 in the event
of fault conditions. For continuous operation, do not
exceed the absolute maximum junction temperature of
+150°C. See the Thermal Considerations section for
more information.
______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
VBAT
PV1
0.1µF
220µF
OUTS2
4.7µF
EN
VOUT1
PWM
2.2µH
LX2
VOUT2
10µF
PGND2
PV3
4.7µF
PV2
MAX16922
BST
4.7µF
4.7µF
0.1µF
OUT3
4.7µH
GND1
GND3
LX1
VOUT2
VOUT1
OUTS1
PV4
10µF
4.7µF
OUT4
4.7µF
Applications Information
Power-On Sequence
When the EN input is pulled high and PV1 is greater
than 3.7V (typ), the 5V LSUP linear regulator turns on.
Once LSUP exceeds 2.5V, the internal reference and
bias are enabled. When the internal bias has stabilized
OUT1, soft-start is initiated. After completion of soft-start
on OUT1 (2.8ms typ), OUT2 soft-start is initiated. OUT3
soft-start is enabled when PV3 is greater than or equal
to 1.25V (typ), and OUT4 soft-start is enabled when PV4
is greater than or equal to 1.5V (typ).
Power-Down and Restart Sequence
The MAX16922 can be shut down by thermal shutdown, enable low (EN), LSUP regulator undervoltage,
or when PV1 falls below 3.0V (typ). When a shutdown
occurs, all outputs discharge through an internal resistor connected between each output and ground. When
enable is high, the die temperature is okay, the LSUP
1µF
GND
GND2
VOUT1
LSUP
EP
20kΩ
RESET
linear regulator is greater than 2.5V (typ), and OUT1
and OUT2 are less than 1.25V (typ); a complete softstart power-on sequence is reinitiated.
Inductor Selection
The OUT1 step-down converter operates with a 4.7µH
inductor and the OUT2 step-down converter operates
with a 2.2µH inductor. The inductor’s DC current rating
must be high enough to account for peak ripple current
and load transients. The step-down converter’s architecture has minimal current overshoot during startup
and load transients. In most cases, an inductor capable
of 1.3 times the maximum load current is acceptable.
For optimum performance choose an inductor with DCseries resistance in the 50mΩ to 150mΩ range. For
higher efficiency at heavy loads (above 400mA) and
minimal load regulation, the inductor resistance should
be kept as small as possible. For light-load applications
(up to 200mA), higher resistance is acceptable with
very little impact on performance.
______________________________________________________________________________________
13
MAX16922
Typical Applications Circuit
MAX16922
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
Capacitor Selection
Input Capacitors
The input capacitor, CIN1, reduces the current peaks
drawn from the supply and reduces switching noise in
the MAX16922. The impedance of CIN1 at the switching frequency should be kept very low. Ceramic capacitors with X5R or X7R dielectrics are recommended due
to their small size, low ESR, and small temperature
coefficients. Use a 4.7µF ceramic capacitor or an
equivalent amount of multiple capacitors in parallel
between PV1 and ground. Connect CIN1 as close to
the device as possible to minimize the impact of PCB
trace inductance.
Connect a minimum 4.7µF ceramic capacitor between
PV2 to ground, and a 2.2µF ceramic capacitor between
PV3 to ground and PV4 to ground. Since PV2 is cascaded from OUT1, the input capacitor connected to
PV2 can be used as part of the total output capacitance
for OUT1.
Step-Down Output Capacitors
The step-down output capacitors are required to keep
the output-voltage ripple small and to ensure regulation
loop stability. These capacitors must have low impedance at the switching frequency. Surface-mount ceramic capacitors are recommended due to their small size
and low ESR. The capacitor should maintain its
capacitance overtemperature and DC bias. Ceramic
capacitors with X5R or X7R temperature characteristics
generally perform well. The output capacitance can be
very low. Place a minimum of 15µF ceramic capacitance from OUTS1 to ground and a minimum of 10µF
from OUTS2 to ground. When the OUT2 output voltage
selection is below 2.35V, the output capacitance should
be increased to prevent instability. For optimum loadtransient performance and very low output ripple, the
output capacitance can be increased. The maximum
output capacitance should not exceed 3.8mF for OUT1
and 2.0mF for OUT2.
LDO Output Capacitors and Stability
Connect a 4.7µF ceramic capacitor between OUT3 and
GND, and a second 4.7µF ceramic capacitor from
OUT4 to GND. When the input voltage of an LDO is
greater than 2.35V, the output capacitor can be
decreased to 2.2µF. The equivalent series resistance
14
(ESR) of the LDO output capacitors affects stability and
output noise. Use output capacitors with an ESR of
0.1Ω or less to ensure stable operation and optimum
transient response. Connect these capacitors as close
as possible to the device to minimize PCB trace inductance.
Thermal Considerations
The maximum package power dissipation of the
MAX16922 in the 20-pin thin QFN package is 2500mW.
The power dissipated by the MAX16922 should not
exceed this rating. The total device power dissipation is
the sum of the power dissipation of the four regulators:
PD = PD1 + PD2 + PD3 + PD4
Estimate the OUT1 and OUT2 power dissipations as
follows:
1− η
η
1− η
PD2 = IOUT2 × VOUT2 ×
η
PD1 = IOUT1 × VOUT1 ×
where η is the efficiency (see the Typical Operating
Characteristics section).
Calculate the OUT3 and OUT4 power dissipations as
follows:
PD3 = IOUT3 x (VPV3 – VOUT3)
PD4 = IOUT4 x (VPV4 – VOUT4)
The maximum junction temperature of the MAX16922 is
+150°C. The junction-to-case thermal resistance (θJC)
of the MAX16922 is 2.7°C/W.
When mounted on a single-layer PCB, the junction to
ambient thermal resistance (θ JA ) is approximately
48°C/W. Mounted on a multilayer PCB, θJA is approximately32°C/W. Calculate the junction temperature of
the MAX16922 as follows:
TJ = TA x PD x θJA
where TA is the maximum ambient temperature. Make
sure the calculated value of TJ does not exceed the
+150°C maximum.
______________________________________________________________________________________
2.2MHz, Dual, Step-Down DC-DC
Converters, Dual LDOs, and RESET
The OUTS_ feedback connections are sensitive to
inductor magnetic field interference so route these
traces away from the inductors and noisy traces such
as LX_.
Connect GND_ and PGND2 to the ground plane.
Connect the exposed paddle to the ground plane
with multiple vias to help conduct heat away from
the device.
Refer to the MAX16922 evaluation kit for a PCB layout
example.
Selector Guide
MAX16922 ATP
x
/V
+
LEAD FREE
AEC Q100 QUALIFIED
OUTPUT VOLTAGES RESET THRESHOLD, RESET TIMEOUT
-40°C TO +125°C OPERATION, TQFN, 20 PINS
MAX16922
AUP x
/V
+
LEAD FREE
AEC Q100 QUALIFIED
OUTPUT VOLTAGES RESET THRESHOLD, RESET TIMEOUT
-40°C TO +125°C OPERATION, TSSOP, 20 PINS
PART
NUMBER
SUFFIX*
OUT1
VOLTAGE
(V)
OUT2
VOLTAGE
(V)
OUT3
VOLTAGE
(V)
OUT4
VOLTAGE
(V)
OUT1 RESET
THRESHOLD
(%)
RESET
TIMEOUT
(ms)
BST
REFRESH
LOAD
ENABLE
A
5.00
2.70
3.30
1.0
90
14.9
On
B
5.00
1.20
1.80
3.3
90
14.9
On
C
5.00
3.30
1.20
3.0
90
14.9
On
D
3.6
1.2
3.3
3.3
90
14.9
Off
E
5.00
3.30
2.50
1.80
90
14.9
On
On
F
5.00
1.20
3.15
3.00
90
14.9
G
3.30
Off
2.80
1.80
90
14.9
On
H
3.30
1.20
2.50
1.80
90
14.9
Off
*Other standard versions may be available. Contact factory for availability.
______________________________________________________________________________________
15
MAX16922
PCB Layout
High-switching frequencies and relatively large peak
currents make PCB layout a very important aspect of
design. Good design minimizes excessive EMI on the
feedback paths and voltage gradients in the ground
plane, both of which can result in instability or regulation errors. Connect the input capacitors as close as
possible to the PV_ and ground. Connect the inductor
and output capacitors as close as possible to the
device and keep the traces short, direct, and wide to
minimize the current loop area.
MAX16922
2.2MHz, Dual,, Step-Down DC-DC
Converters, Dual LDOs, and RESET
Package Information
Chip Information
PROCESS: BiCMOS
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in
the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
20 TQFN-EP
T2055+4
21-0140
20 TSSOP-EP
U20E+1
21-0108
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.