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LMZ31704
SLVSBV8E – JUNE 2013 – REVISED FEBRUARY 2020
LMZ31704 4-A Power Module with 2.95-V to 17-V Input and
Current Sharing in QFN Package
1 Features
3 Description
•
The LMZ31704 power module is an easy-to-use
integrated power solution that combines a 4-A DC/DC
converter with power MOSFETs, a shielded inductor,
and passives into a low profile, QFN package. This
total power solution allows as few as three external
components and eliminates the loop compensation
and magnetics part selection process.
1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Complete integrated power solution allows
small footprint, low-profile design
10-mm × 10-mm × 4.3-mm package
– Pin compatible with LMZ31710 and LMZ31707
Efficiencies up to 95%
Eco-mode™ / light load efficiency (LLE)
Wide-output voltage adjust
0.6 V to 5.5 V, with 1% reference accuracy
Supports parallel operation for higher current
Optional split power rail allows
input voltages down to 2.95 V
Adjustable switching frequency
(200 kHz to 1.2 MHz)
Synchronizes to an external clock
Provides 180° out-of-phase clock signal
Adjustable slow start
Output voltage sequencing / tracking
Power good output
Programmable undervoltage lockout (UVLO)
Overcurrent and overtemperature protection
Pre-bias output start-up
Operating temperature range: –40°C to 85°C
Enhanced thermal performance: 13.3°C/W
Meets EN55022 Class B emissions
– Integrated shielded inductor
Create a custom design using the LMZ31704 with
the WEBENCH® Power Designer
2 Applications
•
•
•
•
Broadband and communications infrastructure
Automated test and medical equipment
Compact PCI / PCI express / PXI express
DSP and FPGA point-of-load applications
The 10 × 10 × 4.3 mm QFN package is easy to
solder onto a printed circuit board and allows a
compact point-of-load design. Achieves greater than
95% efficiency and excellent power dissipation
capability with a thermal impedance of 13.3°C/W. The
LMZ31704 offers the flexibility and the feature-set of
a discrete point-of-load design and is ideal for
powering a wide range of ICs and systems.
Advanced packaging technology affords a robust and
reliable power solution compatible with standard QFN
mounting and testing techniques.
Simplified Application
VIN
CIN
PVIN
VIN
ISHARE
VOUT
VOUT
SENSE+
COUT
LMZ31704
SYNC_OUT
PWRGD
INH/UVLO
VADJ
SS/TR
RT/CLK
STSEL
AGND PGND
RSET
RRT
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LMZ31704
SLVSBV8E – JUNE 2013 – REVISED FEBRUARY 2020
www.ti.com
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision D (March 2019) to Revision E
•
Page
Added VOUT Range values under different IOUT conditions in Table 7 .................................................................................. 24
Changes from Revision C (April 2018) to Revision D
Page
•
Added ESD Ratings information............................................................................................................................................. 3
•
Corrected TBD values in Synchronization Frequency vs Output Voltage Table.................................................................. 24
Changes from Revision B (June 2017) to Revision C
Page
•
Added WEBENCH® design links for the LMZ31704.............................................................................................................. 1
•
Increased the peak reflow temperature and maximum number of reflows to JEDEC specifications for improved
manufacturability..................................................................................................................................................................... 3
•
Added Device Support section ............................................................................................................................................. 29
•
Added Mechanical, Packaging, and Orderable Information section .................................................................................... 30
Changes from Revision A (August 2013) to Revision B
•
2
Page
Added peak reflow and maximum number of reflows information ........................................................................................ 3
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SLVSBV8E – JUNE 2013 – REVISED FEBRUARY 2020
5 Specifications
5.1 Absolute Maximum Ratings (1)
over operating temperature range (unless otherwise noted)
MIN
MAX
UNIT
VIN, PVIN
–0.3
20
V
INH/UVLO, PWRGD, RT/CLK, SENSE+
–0.3
6
V
ILIM, VADJ, SS/TR, STSEL, SYNC_OUT, ISHARE, OCP_SEL
–0.3
3
V
PH
–1.0
20
V
PH 10 ns Transient
–3.0
20
V
VOUT
–0.3
6
V
±100
µA
PH
current limit
A
PH
current limit
A
PVIN
current limit
A
–0.1
2
mA
Operating Junction Temperature
–40
125 (2)
°C
Storage Temperature
–65
150
°C
245 (4)
°C
Input Voltage
Output Voltage
RT/CLK, INH/UVLO
Source Current
Sink Current
PWRGD
Peak Reflow Case Temperature (3)
Maximum Number of Reflows Allowed
(3)
3
Mechanical Shock
Mil-STD-883D, Method 2002.3, 1 msec, 1/2 sine, mounted
Mechanical Vibration
Mil-STD-883D, Method 2007.2, 20-2000Hz
(1)
(4)
1500
G
20
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 under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
See the temperature derating curves in the Typical Characteristics section for thermal information.
For soldering specifications, refer to the Soldering Requirements for BQFN Packages application note.
Devices with a date code prior to week 14 2018 (1814) have a peak reflow case temperature of 240°C with a maximum of one reflow.
(2)
(3)
(4)
5.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic
discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±1500
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
5.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
UNIT
PVIN
Input Switching Voltage
2.95
17
V
VIN
Input Bias Voltage
4.5
17
V
VOUT
Output Voltage
0.6
5.5
V
fSW
Switching Frequency
200
1200
kHz
5.4 Package Specifications
LMZ31704
Weight
Flammability
MTBF Calculated reliability
UNIT
1.45 grams
Meets UL 94 V-O
Per Bellcore TR-332, 50% stress, TA = 40°C, ground benign
37.4 MHrs
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SLVSBV8E – JUNE 2013 – REVISED FEBRUARY 2020
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5.5 Thermal Information
LMZ31704
THERMAL METRIC (1)
RVQ42
UNIT
42 PINS
Junction-to-ambient thermal resistance (2)
θJA
ψJT
Junction-to-top characterization parameter
ψJB
Junction-to-board characterization parameter (4)
(1)
(2)
(3)
(4)
13.3
°C/W
1.6
°C/W
5.3
°C/W
(3)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
The junction-to-ambient thermal resistance, θJA, applies to devices soldered directly to a 100 mm x 100 mm double-sided PCB with 2 oz.
copper and natural convection cooling. Additional airflow reduces θJA.
The junction-to-top characterization parameter, ψJT, estimates the junction temperature, TJ, of a device in a real system, using a
procedure described in JESD51-2A (sections 6 and 7). TJ = ψJT * Pdis + TT; where Pdis is the power dissipated in the device and TT is
the temperature of the top of the device.
The junction-to-board characterization parameter, ψJB, estimates the junction temperature, TJ, of a device in a real system, using a
procedure described in JESD51-2A (sections 6 and 7). TJ = ψJB * Pdis + TB; where Pdis is the power dissipated in the device and TB is
the temperature of the board 1mm from the device.
5.6
Electrical Characteristics
Over –40°C to 85°C free-air temperature, PVIN = VIN = 12 V, VOUT = 1.8 V, IOUT = 4 A,
CIN = 0.1 µF + 2 x 22 µF ceramic + 100 µF bulk, COUT = 4 x 47 µF ceramic (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
IOUT
Output current
TA = 85°C, natural convection
0 (1)
4
A
VIN
Input bias voltage range
Over output current range
4.5
17
V
PVIN
Input switching voltage range
Over output current range
2.95 (2)
17 (3)
V
UVLO
VIN Undervoltage lockout
VOUT(adj)
VOUT
VIN Increasing
VIN Decreasing
3.5
Output voltage adjust range
Over output current range
0.6
Set-point voltage tolerance
TA = 25°C, IOUT = 0 A
Temperature variation
–40°C ≤ TA ≤ +85°C, IOUT = 0 A
±0.2%
Line regulation
Over input voltage range
±0.1%
Load regulation
Over output current range
±0.2%
Total output voltage variation
Includes set-point, line, load, and temperature variation
PVIN = VIN = 12 V
IO = 3 A
η
Efficiency
PVIN = VIN = 5 V
IO = 3 A
Output voltage ripple
ILIM
Current limit threshold
Transient response
(1)
(2)
(3)
(4)
4
4
4.5
3.85
5.5
V
V
±1% (4)
±1.5% (4)
VOUT = 5.0 V, fSW = 1 MHz
94 %
VOUT = 3.3 V, fSW = 750 kHz
92 %
VOUT = 2.5 V, fSW = 750 kHz
89 %
VOUT = 1.8 V, fSW = 500 kHz
88 %
VOUT = 1.2 V, fSW = 300 kHz
86 %
VOUT = 0.9 V, fSW = 250 kHz
84 %
VOUT = 0.6 V, fSW = 200 kHz
81 %
VOUT = 3.3 V, fSW = 750 kHz
95 %
VOUT = 2.5 V, fSW = 750 kHz
94 %
VOUT = 1.8 V, fSW = 500 kHz
93 %
VOUT = 1.2 V, fSW = 300 kHz
91 %
VOUT = 0.9 V, fSW = 250 kHz
89 %
VOUT = 0.6 V, fSW = 200 kHz
86 %
20 MHz bandwith
14
mVP-P
ILIM pin open
9
A
ILIM pin to AGND
6
A
Recovery time
100
µs
VOUT over/undershoot
80
mV
1.0 A/µs load step from
25 to 75% IOUT(max)
See the Light Load Efficiency (LLE) section for more information for output voltages < 1.5 V.
The minimum PVIN is 2.95 V or (VOUT + 0.7 V), whichever is greater. See for more details.
The maximum PVIN voltage is 17 V or (22 x VOUT), whichever is less. See for more details.
The stated limit of the set-point voltage tolerance includes the tolerance of both the internal voltage reference and the internal
adjustment resistor. The overall output voltage tolerance will be affected by the tolerance of the external RSET resistor.
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Electrical Characteristics (continued)
Over –40°C to 85°C free-air temperature, PVIN = VIN = 12 V, VOUT = 1.8 V, IOUT = 4 A,
CIN = 0.1 µF + 2 x 22 µF ceramic + 100 µF bulk, COUT = 4 x 47 µF ceramic (unless otherwise noted)
PARAMETER
VINH
Inhibit threshold voltage
IINH
II(stby)
TEST CONDITIONS
Inhibit Low Voltage
-0.3
1.1
INH Input current
VINH < 1.1 V
-1.15
INH Hysteresis current
VINH > 1.3 V
-3.3
Input standby current
INH pin to AGND
PWRGD Thresholds
VOUT falling
PWRGD Low Voltage
I(PWRGD) = 0.5 mA
Switching frequency
RRT = 169 kΩ
fCLK
Synchronization frequency
VCLK-H
CLK High-Level
VCLK-L
CLK Low-Level
DCLK
CLK Duty Cycle
Thermal Shutdown
2
Good
95%
Fault
108%
Fault
91%
Good
104%
CLK Control
Equivalent series resistance (ESR)
(5)
(6)
(7)
(8)
µA
200
1200
kHz
2.0
5.5
500
50
V
80
%
175
°C
10
°C
µF
100 (6)
47 (7)
V
0.5
44 (6)
Non-ceramic
Non-ceramic
μA
10
V
Thermal shutdown hysteresis
External output capacitance
μA
kHz
Thermal shutdown
Ceramic
V
0.3
20
Ceramic
UNIT
600
400
External input capacitance
COUT
MAX
open (5)
fSW
CIN
TYP
1.3
VOUT rising
Power Good
MIN
Inhibit High Voltage
200
1500
220 (7)
5000 (8)
35
µF
mΩ
This pin has an internal pullup. If it is left open, the device operates when input power is applied. A small, low-leakage MOSFET is
recommended for control. When the device is operating and no UVLO resistor divider is present on this pin, the open voltage is typically
2.9 V.
A minimum of 44 µF of external ceramic capacitance is required across the input (VIN and PVIN connected) for proper operation. An
additional 100 µF of bulk capacitance is recommended. It is also recommended to place a 0.1-µF ceramic capacitor directly across the
PVIN and PGND pins of the device. Locate the input capacitance close to the device. When operating with split VIN and PVIN rails,
place 4.7 µF of ceramic capacitance directly at the VIN pin. See Table 4 for more details.
The amount of required output capacitance varies depending on the output voltage. The amount of required capacitance must include at
least 1x 47-µF ceramic capacitor. Locate the capacitance close to the device. Adding additional capacitance close to the load improves
the response of the regulator to load transients. See Table 3 and Table 4 more details.
When using both ceramic and non-ceramic output capacitors, the combined maximum must not exceed 5000 µF. It may be necessary to
increase the slow start time when turning on into the maximum capacitance. See the Slow Start (SS/TR) section for information on
adjusting the slow start time.
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6 Device Information
Functional Block Diagram
OCP_SEL
ILIM
OCP
INH/UVLO
Shutdown
Logic
PWRGD
VIN
Thermal
Shutdown
SENSE+
VIN
UVLO
PWRGD
Logic
PVIN
+
+
PH
VADJ
SS/TR
VREF
Comp
STSEL
Current
Share
ISHARE
SYNC_OUT
RT/CLK
Power
Stage
and
Control
Logic
Oscillator
with PLL
PGND
AGND
6
VOUT
LMZ31704
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Pin Functions
TERMINAL
NAME
2
AGND
DESCRIPTION
NO.
23
Zero volt reference for the analog control circuit. These pins are not connected together internal to the
device and must be connected to one another using an AGND plane of the PCB. These pins are associated
with the internal analog ground (AGND) of the device. Keep AGND separate from PGND, as a single
connection is made internal to the device. See the Layout Considerations.
20
21
PGND
31
32
This is the return current path for the power stage of the device. Connect these pins to the load and to the
bypass capacitors associated with PVIN and VOUT. Keep PGND separate from AGND, as a single
connection is made internal to the device.
33
VIN
3
Input bias voltage pin. Supplies the control circuitry of the power converter. Connect this pin to the input bias
supply. Connect bypass capacitors between this pin and PGND.
1
11
PVIN
12
Input switching voltage. Supplies voltage to the power switches of the converter. Connect these pins to the
input supply. Connect bypass capacitors between these pins and PGND.
39
40
34
35
VOUT
36
37
Output voltage. These pins are connected to the internal output inductor. Connect these pins to the output
load and connect external bypass capacitors between these pins and PGND.
38
41
10
13
14
15
PH
16
17
Phase switch node. These pins must be connected to one another using a small copper island under the
device for thermal relief. Do not place any external component on these pins or tie them to a pin of another
function.
18
19
42
5
DNC
9
Do not Connect. Do not connect these pins to AGND, to another DNC pin, or to any other voltage. These
pins are connected to internal circuitry. Each pin must be soldered to an isolated pad.
24
ISHARE
25
Current share pin. Connect this pin to the ISHARE pin of the other LMZ31704 device when paralleling
multiple LMZ31704 devices. When unused, treat this pin as a Do Not Connect (DNC) and leave it isolated
from all other signals or ground.
OCP_SEL
4
Overcurrent protection select pin. Leave this pin open for hiccup mode operation. Connect this pin to AGND
for cycle-by-cycle operation. See Overcurrent Protection for more details.
ILIM
6
Current limit pin. Leave this pin open for full current limit threshold. Connect this pin to AGND to reduce the
current limit threshold by approximately 3 A.
SYNC_OUT
7
Synchronization output pin. Provides a 180° out-of-phase clock signal.
PWRGD
8
Power Good flag pin. This open drain output asserts low if the output voltage is more than approximately
±6% out of regulation. A pullup resistor is required.
RT/CLK
22
This pin is connected to an internal frequency setting resistor which sets the default switching frequency. An
external resistor can be connected from this pin to AGND to increase the frequency. This pin can also be
used to synchronize to an external clock.
VADJ
26
Connecting a resistor between this pin and AGND sets the output voltage.
SENSE+
27
Remote sense connection. This pin must be connected to VOUT at the load or at the device pins. Connect
this pin to VOUT at the load for improved regulation.
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Pin Functions (continued)
TERMINAL
DESCRIPTION
NAME
NO.
SS/TR
28
Slow-start and tracking pin. Connecting an external capacitor to this pin adjusts the output voltage rise time.
A voltage applied to this pin allows for tracking and sequencing control.
STSEL
29
Slow-start or track feature select. Connect this pin to AGND to enable the internal SS capacitor. Leave this
pin open to enable the TR feature.
INH/UVLO
30
Inhibit and UVLO adjust pin. Use an open drain or open collector logic device to ground this pin to control
the INH function. A resistor divider between this pin, AGND, and PVIN/VIN sets the UVLO voltage.
8
PVIN
1
AGND
2
VIN
40 39
PGND
PGND
VOUT
VOUT
VOUT
VOUT
VOUT
PVIN
PVIN
RVQ PACKAGE
(TOP VIEW)
38 37 36 35 34 33 32
31
PGND
30
INH/UVLO
3
29
STSEL
OCP_SEL
4
28
SS/TR
DNC
5
27
SENSE+
ILIM
6
26
VADJ
SYNC_OUT
7
25
ISHARE
PWRGD
8
24
DNC
DNC
9
23
AGND
22
RT/CLK
21
PGND
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PGND
PH
PH
PH
14 15 16 17 18 19 20
PH
12 13
PH
11
PH
PH
PVIN
42
PH
10
PVIN
PH
41 VOUT
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7 Typical Characteristics (PVIN = VIN = 12 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 1, Figure 2, and Figure 3. The temperature derating curves represent the conditions at which
internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to devices
soldered directly to a 100-mm × 100-mm, 4-layer PCB with 2-oz. copper. Applies to Figure 4.
30
100
Output Ripple Voltage (mV)
Efficiency (%)
90
80
70
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
60
50
40
0
1
2
3
25
20
15
10
5
0
4
Output Current (A)
3
4
C004
Figure 2. Voltage Ripple versus Output Current
80
Ambient Temperature (ƒC)
Power Dissipation (W)
1.2
2
Output Current (A)
90
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
1.6
1
C001
Figure 1. Efficiency versus Output Current
2.0
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
0.8
0.4
70
60
50
Airflow = 0 LFM
40
30
All Output Voltages
20
0
1
2
3
4
Output Current (A)
0
2
4
C001
Figure 4. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
3
Output Current (A)
Figure 3. Power Dissipation versus Output Current
Gain (dB)
1
C004
Phase (°)
0.0
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 5. VOUT = 1.8 V, IOUT = 4 A, COUT = 200 µF Ceramic, fSW = 500 kHz
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8 Typical Characteristics (PVIN = VIN = 5 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 6, Figure 7, and Figure 8. The temperature derating curves represent the conditions at which
internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to devices
soldered directly to a 100-mm × 100-mm, 4-layer PCB with 2-oz. copper. Applies to Figure 9.
100
30
Output Voltage Ripple (mV)
90
70
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
60
50
40
0
1
2
3
25
20
15
10
5
4
Output Current (A)
0
4
C004
Figure 7. Voltage Ripple versus Output Current
80
Ambient Temperature (ƒC)
Power Dissipation (W)
0.8
3
90
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
1.0
2
Output Current (A)
Figure 6. Efficiency versus Output Current
1.2
1
C001
0.6
0.4
0.2
70
60
50
Airflow = 0 LFM
40
30
0.0
All Output Voltages
20
0
1
2
3
4
Output Current (A)
0
2
4
C001
Figure 9. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
3
Output Current (A)
Figure 8. Power Dissipation versus Output Current
Gain (dB)
1
C004
Phase (°)
Efficiency (%)
80
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 10. VOUT = 1.8 V, IOUT = 4 A, COUT = 200 µF Ceramic, fSW = 500 kHz
10
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9 Typical Characteristics (PVIN = 3.3 V, VIN = 5 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 11, Figure 12, and Figure 13. The temperature derating curves represent the conditions at
which internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to
devices soldered directly to a 100-mm × 100-mm, 4-layer PCB with 2-oz. copper. Applies to Figure 14.
100
30
Output Ripple Voltage (mV)
80
70
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
60
Vo = 1.2V, fsw = 300kHz
50
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
40
0
1
2
3
25
20
15
10
5
4
Output Current (A)
0
4
C004
Figure 12. Voltage Ripple versus Output Current
80
Ambient Temperature (ƒC)
Power Dissipation (W)
0.8
3
90
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
1.0
2
Output Current (A)
Figure 11. Efficiency versus Output Current
1.2
1
C001
0.6
0.4
0.2
70
60
50
Airflow = 0 LFM
40
30
0.0
All Output Voltages
20
0
1
2
3
4
Output Current (A)
0
2
4
C001
Figure 14. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
3
Output Current (A)
Figure 13. Power Dissipation versus Output Current
Gain (dB)
1
C004
Phase (°)
Efficiency (%)
90
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 15. VOUT = 1.8 V, IOUT = 4 A, COUT = 200 µF Ceramic, fSW = 500 kHz
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10 Application Information
10.1 Adjusting the Output Voltage
The VADJ control sets the output voltage of the LMZ31704. The output voltage adjustment range is from 0.6 V to
5.5 V. The adjustment method requires the addition of RSET, which sets the output voltage, the connection of
SENSE+ to VOUT, and in some cases, RRT which sets the switching frequency. The RSET resistor must be
connected directly between the VADJ (pin 26) and AGND (pin 23). The SENSE+ pin (pin 27) must be connected
to VOUT either at the load for improved regulation or at VOUT of the device. The RRT resistor must be connected
directly between the RT/CLK (pin 22) and AGND (pin 23). Table 1 gives the standard external RSET resistor for a
number of common bus voltages, along with the recommended RRT resistor for that output voltage.
Table 1. Standard RSET Resistor Values for Common Output Voltages
RESISTORS
OUTPUT VOLTAGE VOUT (V)
0.9
1.0
1.2
1.8
2.5
3.3
5.0
RSET (kΩ)
2.87
2.15
1.43
0.715
0.453
0.316
0.196
RRT (kΩ)
1000
1000
487
169
90.9
90.9
63.4
For other output voltages, the value of the required resistor can either be calculated using the following formula,
or simply selected from the range of values given in Table 2.
1.43
RSET =
(kW )
æ æ VOUT ö ö
çç
÷ - 1÷
è è 0.6 ø ø
(1)
Table 2. Standard RSET Resistor Values
12
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
0.6
open
OPEN
200
3.1
0.348
90.9
750
0.7
8.66
OPEN
200
3.2
0.332
90.9
750
0.8
4.32
OPEN
200
3.3
0.316
90.9
750
0.9
2.87
1000
250
3.4
0.309
90.9
750
1.0
2.15
1000
250
3.5
0.294
90.9
750
1.1
1.74
1000
250
3.6
0.287
90.9
750
1.2
1.43
487
300
3.7
0.280
90.9
750
1.3
1.24
487
300
3.8
0.267
90.9
750
1.4
1.07
487
300
3.9
0.261
90.9
750
1.5
0.953
487
300
4.0
0.255
90.9
750
1.6
0.866
487
300
4.1
0.243
63.4
1000
1.7
0.787
487
300
4.2
0.237
63.4
1000
1.8
0.715
169
500
4.3
0.232
63.4
1000
1.9
0.665
169
500
4.4
0.226
63.4
1000
2.0
0.619
169
500
4.5
0.221
63.4
1000
2.1
0.576
169
500
4.6
0.215
63.4
1000
2.2
0.536
169
500
4.7
0.210
63.4
1000
2.3
0.511
169
500
4.8
0.205
63.4
1000
2.4
0.475
169
500
4.9
0.200
63.4
1000
2.5
0.453
90.9
750
5.0
0.196
63.4
1000
2.6
0.432
90.9
750
5.1
0.191
63.4
1000
2.7
0.412
90.9
750
5.2
0.187
63.4
1000
2.8
0.392
90.9
750
5.3
0.182
63.4
1000
2.9
0.374
90.9
750
5.4
0.178
63.4
1000
3.0
0.357
90.9
750
5.5
0.174
63.4
1000
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10.2 Capacitor Recommendations for the LMZ31704 Power Supply
10.2.1 Capacitor Technologies
10.2.1.1 Electrolytic, Polymer-Electrolytic Capacitors
When using electrolytic capacitors, high-quality, computer-grade electrolytic capacitors are recommended.
Polymer-electrolytic type capacitors are recommended for applications where the ambient operating temperature
is less than 0°C. The Sanyo OS-CON capacitor series is suggested due to the lower ESR, higher rated surge,
power dissipation, ripple current capability, and small package size. Aluminum electrolytic capacitors provide
adequate decoupling over the frequency range of 2 kHz to 150 kHz, and are suitable when ambient temperatures
are above 0°C.
10.2.1.2 Ceramic Capacitors
The performance of aluminum electrolytic capacitors is less effective than ceramic capacitors above 150 kHz.
Multilayer ceramic capacitors have a low ESR and a resonant frequency higher than the bandwidth of the
regulator. They can be used to reduce the reflected ripple current at the input as well as improve the transient
response of the output.
10.2.1.3 Tantalum, Polymer-Tantalum Capacitors
Polymer-tantalum type capacitors are recommended for applications where the ambient operating temperature is
less than 0°C. The Sanyo POSCAP series and Kemet T530 capacitor series are recommended rather than many
other tantalum types due to their lower ESR, higher rated surge, power dissipation, ripple current capability, and
small package size. Tantalum capacitors that have no stated ESR or surge current rating are not recommended
for power applications.
10.2.2 Input Capacitor
The LMZ31704 requires a minimum input capacitance of 44 μF of ceramic type. An additional 100 µF of nonceramic capacitance is recommended for applications with transient load requirements. The voltage rating of
input capacitors must be greater than the maximum input voltage. At worst case, when operating at 50% duty
cycle and maximum load, the combined ripple current rating of the input capacitors must be at least 2 Arms.
Table 4 includes a preferred list of capacitors by vendor. It is also recommended to place a 0.1 µF ceramic
capacitor directly across the PVIN and PGND pins of the device. When operating with split VIN and PVIN rails,
place 4.7µF of ceramic capacitance directly at the VIN pin.
10.2.3 Output Capacitor
The required output capacitance is determined by the output voltage of the LMZ31704. See Table 3 for the
amount of required capacitance. The effects of temperature and capacitor voltage rating must be considered
when selecting capacitors to meet the minimum required capacitance. The required output capacitance can be
comprised of all ceramic capacitors, or a combination of ceramic and bulk capacitors. The required capacitance
must include at least one 47 µF ceramic. When adding additional non-ceramic bulk capacitors, low-ESR devices
like the ones recommended in Table 4 are required. The required capacitance above the minimum is determined
by actual transient deviation requirements. Table 4 includes a preferred list of capacitors by vendor.
Table 3. Required Output Capacitance
VOUT RANGE (V)
(1)
MINIMUM REQUIRED COUT (µF)
MIN
MAX
0.6
< 0.8
500 µF
(1)
0.8
< 1.2
300 µF
(1)
1.2
< 3.0
200 µF
(1)
3.0
< 4.0
100 µF
(1)
4.0
5.5
47-µF ceramic
Minimum required must include at least one 47-µF ceramic capacitor.
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Table 4. Recommended Input/Output Capacitors (1)
CAPACITOR CHARACTERISTICS
VENDOR
SERIES
PART NUMBER
WORKING
VOLTAGE
(V)
CAPACITANCE
(µF)
ESR (2)
(mΩ)
Murata
X5R
GRM32ER61E226K
25
22
2
TDK
X5R
C3225X5R0J107M
6.3
100
2
TDK
X5R
C3225X5R0J476K
6.3
47
2
Murata
X5R
GRM32ER60J107M
6.3
100
2
Murata
X5R
GRM32ER60J476M
6.3
47
2
100
30
Panasonic
EEH-ZA
EEH-ZA1E101XP
25
Sanyo
POSCAP
16TQC68M
16
68
50
Kemet
T520
T520V107M010ASE025
10
100
25
Sanyo
POSCAP
10TPE220ML
10
220
25
Sanyo
POSCAP
6TPE100MI
6.3
100
25
Sanyo
POSCAP
2R5TPE220M7
2.5
220
7
Kemet
T530
T530D227M006ATE006
6.3
220
6
Kemet
T530
T530D337M006ATE010
6.3
330
10
Sanyo
POSCAP
2TPF330M6
2.0
330
6
Sanyo
POSCAP
6TPE330MFL
6.3
330
15
(1)
(2)
Capacitor Supplier Verification, RoHS, Lead-free and Material Details
Consult capacitor suppliers regarding availability, material composition, RoHS and lead-free status, and manufacturing process
requirements for any capacitors identified in this table.
Maximum ESR at 100 kHz, 25°C.
10.3 Transient Response
Table 5. Output Voltage Transient Response
CIN1 = 3x 22 µF CERAMIC, CIN2 = 100 µF POLYMER-TANTALUM
VOLTAGE DEVIATION (mV)
VOUT (V)
0.6
COUT1 CERAMIC
COUT2 BULK
1 A LOAD STEP,
(1 A/µs)
2 A LOAD STEP,
(1 A/µs)
5
500 µF
220 µF
15
30
90
12
500 µF
220 µF
15
30
90
300 µF
220 µF
20
40
95
300 µF
470 µF
18
35
95
300 µF
220 µF
20
35
95
300 µF
470 µF
18
30
95
200 µF
220 µF
30
50
100
200 µF
470 µF
25
45
100
200 µF
220 µF
25
45
100
200 µF
470 µF
20
40
100
200 µF
220 µF
40
70
110
200 µF
470 µF
35
65
110
200 µF
220 µF
35
65
120
200 µF
470 µF
30
60
120
5
100 µF
220 µF
55
105
130
12
100 µF
220 µF
65
115
150
5
0.9
12
5
1.2
12
5
1.8
12
3.3
14
RECOVERY TIME
(µs)
VIN (V)
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10.4 Transient Waveforms
Figure 16. PVIN = 12 V, VOUT = 1.2-V, 2-A Load Step
Figure 17. PVIN = 12 V, VOUT = 1.8-V, 2-A Load Step
Figure 18. PVIN = 5 V, VOUT = 0.9-V, 2-A Load Step
Figure 19. PVIN = 5 V, VOUT = 1.8-V, 2-A Load Step
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10.5 Application Schematics
LMZ31704
VIN
VIN / PVIN
4.5 V to 17 V
VOUT
1.2 V
SENSE+
PVIN
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
ISHARE
SYNC_OUT
COUT1
2x 100 µF
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
RRT
487 k
VADJ
STSEL AGND PGND
RSET
1.43 k
Figure 20. Typical Schematic
PVIN = VIN = 4.5 V to 17 V, VOUT = 1.2 V
LMZ31704
VIN
VIN / PVIN
4.5 V to 17 V
PVIN
VOUT
3.3 V
SENSE+
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
COUT1
100 µF
ISHARE
SYNC_OUT
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
VADJ
STSEL AGND PGND
RSET
316
RRT
90.9 k
Figure 21. Typical Schematic
PVIN = VIN = 4.5 V to 17 V, VOUT = 3.3 V
16
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Application Schematics (continued)
VIN
4.5 V to 17 V
CIN3
4.7 µF
VIN LMZ31704
VOUT
1.0 V
SENSE+
PVIN
3.3 V
PVIN
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
ISHARE
SYNC_OUT
COUT1
3x 100 µF
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
VADJ
STSEL AGND PGND
RSET
2.15 k
RRT
1M
Figure 22. Typical Schematic
PVIN = 3.3 V, VIN = 4.5 V to 17 V, VOUT = 1.0 V
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10.6 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMZ31704 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
10.7 VIN and PVIN Input Voltage
The LMZ31704 allows for a variety of applications by using the VIN and PVIN pins together or separately. The
VIN voltage supplies the internal control circuits of the device. The PVIN voltage provides the input voltage to the
power converter system.
If tied together, the input voltage for the VIN pin and the PVIN pin can range from 4.5 V to 17 V. If using the VIN
pin separately from the PVIN pin, the VIN pin must be greater than 4.5 V, and the PVIN pin can range from as
low as 2.95 V to 17 V. When operating from a split rail, it is recommended to supply VIN from 5 V to 12 V, for
best performance. A voltage divider connected to the INH/UVLO pin can adjust either input voltage UVLO
appropriately. See the Programmable Undervoltage Lockout (UVLO) section of this datasheet for more
information.
10.8 3.3 V PVIN Operation
Applications operating from a PVIN of 3.3 V must provide at least 4.5 V for VIN. It is recommended to supply VIN
from 5 V to 12 V, for best performance. See the Powering LMZ3 Devices from a 3.3-V Bus Application Report for
help creating 5 V from 3.3 V using a small, simple charge pump device.
10.9 Power Good (PWRGD)
The PWRGD pin is an open-drain output. Once the voltage on the SENSE+ pin is between 95% and 104% of the
set voltage, the PWRGD pin pulldown is released and the pin floats. The recommended pullup resistor value is
between 10 kΩ and 100 kΩ to a voltage source that is 5.5 V or less. The PWRGD pin is in a defined state once
VIN is greater than 1.0 V, but with reduced current sinking capability. The PWRGD pin achieves full current
sinking capability once the VIN pin is above 4.5 V. The PWRGD pin is pulled low when the voltage on SENSE+
is lower than 91% or greater than 108% of the nominal set voltage. Also, the PWRGD pin is pulled low if the
input UVLO or thermal shutdown is asserted, the INH pin is pulled low, or the SS/TR pin is below 1.4 V.
10.10 SYNC_OUT
The LMZ31704 provides a 180° out-of-phase clock signal for applications requiring synchronization. The
SYNC_OUT pin produces a 50% duty cycle clock signal that is the same frequency as the switching frequency of
the device, but is 180° out of phase. Operating two devices 180° out of phase reduces input and output voltage
ripple. The SYNC_OUT clock signal is compatible with other LMZ3 devices that have a CLK input.
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10.11 Parallel Operation
Up to six LMZ31704 devices can be paralleled for increased output current. Multiple connections must be made
between the paralleled devices and the component selection is slightly different than for a stand-alone
LMZ31704 device. A typical LMZ31704 parallel schematic is shown in Figure 23. Refer to the LMZ31710 Parallel
Operation Application Report for information and design help when paralleling multiple LMZ31704 devices.
VIN = 12V
PWRGD
VIN
PVIN
SENSE+
220µF
22µF
0.1µF
LMZ31704
22µF
100µF
100µF
VADJ
SS/TR
PGND
RSET
715 Ω
0.1µF
LMZ31704
PWRGD
SENSE+
VOUT
SYNC_OUT
RT/CLK
330µF
VADJ
VIN
PVIN
100µF
AGND
CSS
SS/TR
Voltage
Supervisor
CSH
INH
Control
ISHARE
5V
100µF
STSEL
ISHARE
RRT
169kΩ
INH/UVLO
Sync Freq
500KHz
INH/UVLO
SYNC_OUT
RT/CLK
VO = 1.8V
VOUT
STSEL
AGND
RRT
169kΩ
PGND
Figure 23. Typical LMZ31704 Parallel Schematic
10.12 Light Load Efficiency (LLE)
The LMZ31704 operates in pulse skip mode at light load currents to improve efficiency and decrease power
dissipation by reducing switching and gate drive losses.
These pulses may cause the output voltage to rise when there is no load to discharge the energy. For output
voltages < 1.5 V, a minimum load is required. The amount of required load can be determined by Equation 2. In
most cases, the minimum current drawn by the load circuit will be enough to satisfy this load. Applications
requiring a load resistor to meet the minimum load, the added power dissipation will be ≤ 3.6 mW. A single 0402
size resistor across VOUT and PGND can be used.
(2)
When VOUT = 0.6 V and RSET = OPEN, the minimum load current is 600 µA.
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10.13 Power-Up Characteristics
When configured as shown in the front page schematic, the LMZ31704 produces a regulated output voltage
following the application of a valid input voltage. During the power-up, internal soft-start circuitry slows the rate
that the output voltage rises, thereby limiting the amount of in-rush current that can be drawn from the input
source. Figure 24 shows the start-up waveforms for a LMZ31704, operating from a 5-V input (PVIN=VIN) and
with the output voltage adjusted to 1.8 V. Figure 25 shows the start-up waveforms for a LMZ31704 starting up
into a pre-biased output voltage.
Figure 24. Start-up Waveforms
Figure 25. Start-up into Pre-bias
10.14 Pre-Biased Start-up
The LMZ31704 has been designed to prevent the low-side MOSFET from discharging a pre-biased output.
During pre-biased startup, the low-side MOSFET does not turn on until the high-side MOSFET has started
switching. The high-side MOSFET does not start switching until the slow-start voltage exceeds the voltage on the
VADJ pin. Refer to Figure 25.
10.15 Remote Sense
The SENSE+ pin must be connected to VOUT at the load, or at the device pins.
Connecting the SENSE+ pin to VOUT at the load improves the load regulation performance of the device by
allowing it to compensate for any I-R voltage drop between its output pins and the load. An I-R drop is caused by
the high output current flowing through the small amount of pin and trace resistance. This should be limited to a
maximum of 300 mV.
NOTE
The remote sense feature is not designed to compensate for the forward drop of nonlinear
or frequency dependent components that may be placed in series with the converter
output. Examples include OR-ing diodes, filter inductors, ferrite beads, and fuses. When
these components are enclosed by the SENSE+ connection, they are effectively placed
inside the regulation control loop, which can adversely affect the stability of the regulator.
10.16 Thermal Shutdown
The internal thermal shutdown circuitry forces the device to stop switching if the junction temperature exceeds
175°C typically. The device reinitiates the power-up sequence when the junction temperature drops below 165°C
typically.
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10.17 Output On/Off Inhibit (INH)
The INH pin provides electrical on/off control of the device. Once the INH pin voltage exceeds the threshold
voltage, the device starts operation. If the INH pin voltage is pulled below the threshold voltage, the regulator
stops switching and enters low quiescent current state. The INH pin has an internal pullup current source,
allowing the user to float the INH pin for enabling the device.
If an application requires controlling the INH pin, use an open drain/collector device, or a suitable logic gate to
interface with the pin. Using a voltage superviser to control the INH pin allows control of the turnon and turnoff of
the device as opposed to relying on the ramp up or down if the input voltage source.
Figure 26 shows the typical application of the inhibit function. Turning Q1 on applies a low voltage to the inhibit
control (INH) pin and disables the output of the supply, shown in Figure 27. If Q1 is turned off, the supply
executes a soft-start power-up sequence, as shown in Figure 28. A regulated output voltage is produced within
2 ms.
INH/UVLO
Q1
INH
Control
AGND
STSEL
SS/TR
Figure 26. Typical Inhibit Control
Figure 27. Inhibit Turnoff
Figure 28. Inhibit Turnon
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10.18 Slow Start (SS/TR)
Connecting the STSEL pin to AGND and leaving SS/TR pin open enables the internal SS capacitor with a slow
start interval of approximately 1.2 ms. Adding additional capacitance between the SS pin and AGND increases
the slow start time. Increasing the slow start time reduces inrush current seen by the input source and reduce the
current seen by the device when charging the output capacitors. To avoid the activation of current limit and
ensure proper start-up, the SS capacitor may need to be increased when operating near the maximum output
capacitance limit.
Figure 29 shows an additional SS capacitor connected to the SS/TR pin and the STSEL pin connected to AGND.
See Table 6 for SS capacitor values and timing interval.
SS/TR
CSS
(Optional)
AGND
STSEL
Figure 29. Slow-Start Capacitor (CSS) and STSEL Connection
Table 6. Slow-Start Capacitor Values and Slow-Start Time
22
CSS (nF)
OPEN
3.3
4.7
10
15
22
33
SS Time (msec)
1.2
2.1
2.5
3.8
5.1
7.0
9.8
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10.19 Overcurrent Protection
For protection against load faults, the LMZ31704 incorporates output overcurrent protection. The overcurrent
protection mode can be selected using the OCP_SEL pin. Leaving the OCP_SEL pin open selects hiccup mode
and connecting it to AGND selects cycle-by-cycle mode. In hiccup mode, applying a load that exceeds the
overcurrent threshold of the regulator causes the regulated output to shut down. Following shutdown, the module
periodically attempts to recover by initiating a soft-start power-up as shown in Figure 30. This is described as a
hiccup mode of operation, whereby the module continues in a cycle of successive shutdown and power up until
the load fault is removed. During this period, the average current flowing into the fault is significantly reduced
which reduces power dissipation. Once the fault is removed, the module automatically recovers and returns to
normal operation as shown in Figure 31.
In cycle-by-cycle mode, applying a load that exceeds the overcurrent threshold of the regulator limits the output
current and reduces the output voltage as shown in Figure 32. During this period, the current flowing into the
fault remains high causing the power dissipation to stay high as well. Once the overcurrent condition is removed,
the output voltage returns to the set-point voltage as shown in Figure 33.
Figure 30. Overcurrent Limiting (Hiccup)
Figure 31. Removal of Overcurrent (Hiccup)
Figure 32. Overcurrent Limiting (Cycle-by-Cycle)
Figure 33. Removal of Overcurrent (Cycle-by-Cycle)
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10.20 Synchronization (CLK)
An internal phase locked loop (PLL) has been implemented to allow synchronization between 200 kHz and
1200 kHz, and to easily switch from RT mode to CLK mode. To implement the synchronization feature, connect
a square wave clock signal to the RT/CLK pin with a duty cycle between 20% to 80%. The clock signal amplitude
must transition lower than 0.5 V and higher than 2.0 V. The start of the switching cycle is synchronized to the
falling edge of RT/CLK pin. In applications where both RT mode and CLK mode are needed, the device can be
configured as shown in Figure 34.
Before the external clock is present, the device works in RT mode and the switching frequency is set by RT
resistor. When the external clock is present, the CLK mode overrides the RT mode. The first time the CLK pin is
pulled above the RT/CLK high threshold (2.0 V), the device switches from RT mode to CLK mode and the
RT/CLK pin becomes high impedance as the PLL starts to lock onto the frequency of the external clock. It is not
recommended to switch from CLK mode back to RT mode because the internal switching frequency drops to
100 kHz first before returning to the switching frequency set by the RT resistor (RRT).
External Clock
200 kHz to 1200 kHz
RT/CLK
RRT
AGND
Figure 34. RT/CLK Configuration
The switching frequency must be selected based on the output voltages of the devices being synchronized.
shows the allowable frequencies for a given range of output voltages. The allowable switching frequency
changes based on the maximum output current (IOUT) of an application. The table shows the VOUT range when
IOUT ≤ 4 A, 3 A, and 2 A. For the most efficient solution, always synchronize to the lowest allowable frequency.
For example, an application requires synchronizing three LMZ31704 devices with output voltages of 1.0 V, 1.2 V,
and 1.8 V, all powered from PVIN = 12 V. Table 7 shows that all three output voltages should be synchronized to
300 kHz.
Table 7. Allowable Switching Frequency versus Output Voltage
SWITCHING
FREQUENCY
(kHz)
24
PVIN = 12 V
PVIN = 5 V
VOUT RANGE (V)
VOUT RANGE (V)
IOUT ≤ 4 A
IOUT ≤ 3 A
IOUT ≤ 2 A
IOUT ≤ 4 A
IOUT ≤ 3 A
IOUT ≤ 2 A
200
0.6 - 1.2
0.6 - 1.6
0.6 - 2.0
0.6 - 4.3
0.6 - 4.3
0.6 - 4.2
300
0.8 - 1.8
0.8 - 2.6
0.8 - 3.5
0.6 - 4.3
0.6 - 4.3
0.6 - 4.2
400
1.1 - 2.7
1.1 - 4.1
1.1 - 5.5
0.6 - 4.3
0.6 - 4.3
0.6 - 4.2
500
1.3 - 3.9
1.3 - 5.5
1.3 - 5.5
0.6 - 4.3
0.6 - 4.3
0.6 - 4.2
600
1.6 - 5.5
1.6 - 5.5
1.6 - 5.5
0.8 - 4.3
0.8 - 4.3
0.6 - 4.2
700
1.9 - 5.5
1.9 - 5.5
1.9 - 5.5
0.8 - 4.2
0.8 - 4.2
0.8 - 4.2
800
2.1 - 5.5
2.1 - 5.5
2.1 - 5.5
0.9 - 4.1
0.9 - 4.1
0.8 - 4.1
900
2.4 - 5.5
2.4 - 5.5
2.4 - 5.5
1.0 - 4.0
1.0 - 4.0
0.9 - 4.0
1000
2.6 - 5.5
2.6 - 5.5
2.6 - 5.5
1.1 - 3.9
1.1 - 3.9
1.0 - 3.9
1100
2.9 - 5.5
2.9 - 5.5
2.9 - 5.5
1.2 - 3.8
1.2 - 3.8
1.1 - 3.8
1200
3.2 - 5.5
3.2 - 5.5
3.2 - 5.5
1.5 - 3.7
1.5 - 3.7
1.2 - 3.7
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10.21 Sequencing (SS/TR)
Many of the common power supply sequencing methods can be implemented using the SS/TR, INH and
PWRGD pins. The sequential method is illustrated in Figure 35 using two LMZ31704 devices. The PWRGD pin
of the first device is coupled to the INH pin of the second device which enables the second power supply once
the primary supply reaches regulation. Figure 36 shows sequential turn-on waveforms of two LMZ31704 devices.
INH/UVLO
VOUT1
VOUT
STSEL
PWRGD
INH/UVLO
VOUT2
VOUT
STSEL
PWRGD
Figure 35. Sequencing Schematic
Figure 36. Sequencing Waveforms
Simultaneous power supply sequencing can be implemented by connecting the resistor network of R1 and R2
shown in Figure 37 to the output of the power supply that needs to be tracked or to another voltage reference
source. The tracking voltage must exceed 750 mV before VOUT2 reaches its set-point voltage. The PWRGD
output of the VOUT2 device can remain low if the tracking voltage does not exceed 1.4 V.Figure 38 shows
simultaneous turnon waveforms of two LMZ31704 devices. Use Equation 3 and Equation 4 to calculate the
values of R1 and R2.
R1 =
(VOUT2 ´ 12.6 )
0.6
R2 =
(kW )
(3)
0.6 ´ R1
(kW )
V
( OUT2 - 0.6 )
(4)
VOUT1
VOUT
INH/UVLO
STSEL
SS/TR
VOUT2
VOUT
INH/UVLO
R1
STSEL
SS/TR
R2
Figure 37. Simultaneous Tracking Schematic
Figure 38. Simultaneous Tracking Waveforms
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10.22 Programmable Undervoltage Lockout (UVLO)
The LMZ31704 implements internal UVLO circuitry on the VIN pin. The device is disabled when the VIN pin
voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO rising threshold is 4.5 V (max) with a
typical hysteresis of 150 mV.
If an application requires either a higher UVLO threshold on the VIN pin or a higher UVLO threshold for a
combined VIN and PVIN, then the UVLO pin can be configured as shown in Figure 39 or Figure 40. Table 8 lists
standard values for RUVLO1 and RUVLO2 to adjust the VIN UVLO voltage up.
PVIN
PVIN
VIN
VIN
RUVLO1
RUVLO1
INH/UVLO
INH/UVLO
RUVLO2
RUVLO2
Figure 39. Adjustable VIN UVLO
Figure 40. Adjustable VIN and PVIN Undervoltage Lockout
Table 8. Standard Resistor values for Adjusting VIN UVLO
VIN UVLO (V)
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
RUVLO1 (kΩ)
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
RUVLO2 (kΩ)
21.5
18.7
16.9
15.4
14.0
13.0
12.1
11.3
10.5
9.76
9.31
Hysteresis (mV)
400
415
430
450
465
480
500
515
530
550
565
For a split rail application, if a secondary UVLO on PVIN is required, VIN must be ≥ 4.5 V. Figure 41 shows the
PVIN UVLO configuration. Use Table 9 to select RUVLO1 and RUVLO2 for PVIN. If PVIN UVLO is set for less than
3.5 V, a 5.1-V zener diode should be added to clamp the voltage on the UVLO pin below 6 V.
> 4.5 V
VIN
PVIN
RUVLO1
INH/UVLO
RUVLO2
Figure 41. Adjustable PVIN Undervoltage Lockout, (VIN ≥ 4.5 V)
Table 9. Standard Resistor Values for Adjusting PVIN UVLO, (VIN ≥ 4.5 V)
PVIN UVLO (V)
26
2.9
3.0
3.5
4.0
4.5
RUVLO1 (kΩ)
68.1
68.1
68.1
68.1
68.1
RUVLO2 (kΩ)
47.5
44.2
34.8
28.7
24.3
Hysteresis (mV)
330
335
350
365
385
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For higher PVIN UVLO voltages, see
Table 8 for resistor values
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10.23 Layout Considerations
To achieve optimal electrical and thermal performance, an optimized PCB layout is required. Figure 42 through
Figure 45 shows a typical PCB layout. Some considerations for an optimized layout are:
• Use large copper areas for power planes (PVIN, VOUT, and PGND) to minimize conduction loss and thermal
stress.
• Place ceramic input and output capacitors close to the device pins to minimize high frequency noise.
• Locate additional output capacitors between the ceramic capacitor and the load.
• Keep AGND and PGND separate from one another.
• Place RSET, RRT, and CSS as close as possible to their respective pins.
• Use multiple vias to connect the power planes to internal layers.
Figure 42. Typical Top-Layer Layout
Figure 43. Typical Layer-2 Layout
Figure 44. Typical Layer-3 Layout
Figure 45. Typical Bottom-Layer Layout
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10.24 EMI
The LMZ31704 is compliant with EN55022 Class B radiated emissions. Figure 46 and Figure 47 show typical
examples of radiated emissions plots for the LMZ31704 operating from 5 V and 12 V, respectively. Both graphs
include the plots of the antenna in the horizontal and vertical positions.
Figure 46. Radiated Emissions 5-V Input, 1.8-V Output, 4-A
Load (EN55022 Class B)
28
Figure 47. Radiated Emissions 12-V Input, 1.8-V Output, 4A Load (EN55022 Class B)
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Development Support
11.1.1.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMZ31704 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
Soldering Requirements for BQFN Packages
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.4 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
11.5 Trademarks
Eco-mode, E2E are trademarks of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
12.1 Tape and Reel Information
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
B0 W
Reel
Diameter
Cavity
A0
B0
K0
W
P1
A0
Dimension designed to accommodate the component width
Dimension designed to accommodate the component length
Dimension designed to accommodate the component thickness
Overall width of the carrier tape
Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
User Direction of Feed
Pocket Quadrants
30
Device
Package
Type
Package
Drawing
Pins
SPQ
Reel
Diameter
(mm)
Reel
Width W1
(mm)
A0
(mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
(mm)
Pin1
Quadrant
LMZ31704RVQR
B3QFN
RVQ
42
500
330.0
24.4
10.35
10.35
4.6
16.0
24.0
Q2
LMZ31704RVQT
B3QFN
RVQ
42
250
330.0
24.4
10.35
10.35
4.6
16.0
24.0
Q2
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TAPE AND REEL BOX DIMENSIONS
Width (mm)
W
L
H
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMZ31704RVQR
B3QFN
RVQ
42
500
383.0
353.0
58.0
LMZ31704RVQT
B3QFN
RVQ
42
250
383.0
353.0
58.0
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PACKAGE OPTION ADDENDUM
www.ti.com
28-Jun-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
LMZ31704RVQR
ACTIVE
B3QFN
RVQ
42
500
RoHS Exempt
& Green
NIPDAU
Level-3-245C-168 HR
-40 to 85
(54020, LMZ31704)
LMZ31704RVQT
ACTIVE
B3QFN
RVQ
42
250
RoHS Exempt
& Green
NIPDAU
Level-3-245C-168 HR
-40 to 85
(54020, LMZ31704)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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