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LMZ31506
SNVS993B – JUNE 2013 – REVISED APRIL 2018
LMZ31506 6-A Power Module With 2.95-V to 14.5-V Input
and Current Sharing in QFN Package
1 Features
3 Description
•
The LMZ31506 power module is an easy-to-use
integrated power solution that combines a 6-A DC-toDC 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
9-mm × 15-mm × 2.8-mm package
- Pin Compatible with LMZ31503
Efficiencies Up To 96%
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 Voltage down to 1.6 V
Adjustable Switching Frequency
(250 kHz to 780 kHz)
Synchronizes to an External Clock
Adjustable Slow-Start
Output Voltage Sequencing / Tracking
Power Good Output
Programmable Undervoltage Lockout (UVLO)
Output Overcurrent Protection (Hiccup Mode)
Over-Temperature Protection
Pre-bias Output Start-up
Operating Temperature Range: –40°C to 85°C
Enhanced Thermal Performance: 13°C/W
Meets EN55022 Class B Emissions
- Integrated Shielded Inductor
Create a Custom Design Using the LMZ31506
With the WEBENCH® Power Designer
The LMZ31506 offers the flexibility and the featureset of a discrete point-of-load design and is ideal for
powering performance DSPs and FPGAs. Advanced
packaging technology afford a robust and reliable
power solution compatible with standard QFN
mounting and testing techniques.
Simplified Application
VIN
VIN
ISHARE
PVIN
PWRGD
LMZ31506
CIN
VOUT
VOUT
RT/CLK
SENSE+
INH/UVLO
2 Applications
•
•
•
•
The 9×15×2.8 mm QFN package is easy to solder
onto a printed circuit board and allows a compact
point-of-load design with greater than 90% efficiency
and excellent power dissipation with a thermal
impedance of 13°C/W junction to ambient. The
device delivers the full 6-A rated output current at
85°C ambient temperature without airflow.
Broadband & Communications Infrastructure
Automated Test and Medical Equipment
Compact PCI, PCI Express and PXI Express
DSP and FPGA Point of Load Applications
SS/TR
COUT
VADJ
RSET
STSEL
AGND
PGND
Efficiency
100
95
Efficiency (%)
90
85
80
75
VOUT = 3.3 V
fSW = 630 kHz
70
65
60
PVIN = VIN = 5 V
PVIN = VIN = 12 V
55
50
0
1
2
3
4
Output Current (A)
5
6
G000
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.
LMZ31506
SNVS993B – JUNE 2013 – REVISED APRIL 2018
www.ti.com
4 Specifications
4.1
Absolute Maximum Ratings (1)
over operating temperature range (unless otherwise noted)
VALUE
Input Voltage
Output Voltage
MAX
VIN, PVIN, INH/UVLO
–0.3
16
V
PWRGD, RT/CLK
–0.3
6
V
VADJ, SS/TR, STSEL, ISHARE
–0.3
3
V
PH
–1
20
V
PH 10ns Transient
–3
20
V
–0.2
0.2
V
VDIFF (GND to exposed
thermal pad)
RT/CLK
Source Current
Sink Current
UNIT
MIN
+100
µA
PH
–100
Current Limit
A
PH
Current Limit
A
PVIN
Current Limit
A
–0.1
5
mA
Operating Junction Temperature
–40
125 (2)
°C
Storage Temperature
–65
150
°C
245 (4)
°C
PWRGD
Peak Reflow Case Temperature (3)
Maximum Number of Reflows Allowed (3)
3 (4)
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)
(2)
(3)
(4)
2
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.
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4.2 Thermal Information
LMZ31506
THERMAL METRIC (1)
RUQ47
UNIT
47 PINS
Junction-to-ambient thermal resistance (2)
θJA
(3)
θJCtop
Junction-to-case (top) thermal resistance
θJCbot
Junction-to-case (bottom) thermal resistance
θJB
Junction-to-board thermal resistance
(4)
(5)
(6)
ψJT
Junction-to-top characterization parameter
ψJB
Junction-to-board characterization parameter (7)
(1)
13
°C/W
9
°C/W
3.8
°C/W
6
°C/W
2.5
°C/W
5
°C/W
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
The junction-to-ambient thermal resistance, θJA, applies to devices soldered directly to a 100 mm × 100 mm double-sided PCB with
1 oz. copper and natural convection cooling. Additional airflow reduces θJA.
The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific JEDECstandard
test exists, but a close description can be found in the ANSI SEMI standard G30-88.
The junction-to-case (bottom) thermal resistance is obtained by simulating a cold plate test on the exposed (power) pad. No specific
JEDEC standard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB
temperature, as described in JESD51-8.
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.
(2)
(3)
(4)
(5)
(6)
(7)
4.3 Package Specifications
LMZ31506
UNIT
Weight
Flammability
MTBF Calculated reliability
4.4
1.26 grams
Meets UL 94 V-O
Per Bellcore TR-332, 50% stress, TA = 40°C, ground benign
33.9 MHrs
Electrical Characteristics
Over –40°C to 85°C free-air temperature, PVIN = VIN = 12 V, VOUT = 1.8 V, IOUT = 6 A,
CIN1 = 2 x 22 µF ceramic, CIN2 = 68 µF poly-tantalum, COUT1 = 4 × 47 µF ceramic (unless otherwise noted)
PARAMETER
TEST CONDITIONS
IOUT
Output current
TA = 85°C, natural convection
VIN
Input bias voltage range
PVIN
Input switching voltage range
UVLO
VOUT(adj)
VOUT
(1)
(2)
(3)
VIN Undervoltage lockout
MIN
TYP
MAX
UNIT
0
6
A
Over IOUT range
4.5
14.5
V
Over IOUT range
1.6 (1)
14.5 (2)
V
VIN = increasing
4.0
VIN = decreasing
3.5
0.6
4.5
3.85
(2)
Output voltage adjust range
Over IOUT range
Set-point voltage tolerance
TA = 25°C, IOUT = 0A
5.5
Temperature variation
-40°C ≤ TA ≤ +85°C, IOUT = 0A
±0.3%
Line regulation
Over PVIN range, TA = 25°C, IOUT = 0A
±0.1%
Load regulation
Over IOUT range, TA = 25°C
±0.1%
Total output voltage variation
Includes set-point, line, load, and temperature variation
±1.0%
(3)
±1.5%
(3)
V
V
The minimum PVIN voltage is 1.6V or (VOUT+ 0.9V), whichever is greater. VIN must be greater than 4.5V.
The maximum PVIN voltage is 14.5V or (15 x VOUT), whichever is less.
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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SNVS993B – JUNE 2013 – REVISED APRIL 2018
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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 = 6 A,
CIN1 = 2 x 22 µF ceramic, CIN2 = 68 µF poly-tantalum, COUT1 = 4 × 47 µF ceramic (unless otherwise noted)
PARAMETER
TEST CONDITIONS
PVIN = VIN = 12 V
IO = 2 A
Efficiency
η
Output voltage ripple
ILIM
PVIN = VIN = 5 V
IO = 2 A
MIN
92 %
VOUT = 3.3 V, fSW = 630 kHz
91 %
VOUT = 2.5 V, fSW = 530 kHz
89 %
VOUT = 1.8 V, fSW = 480 kHz
88 %
VOUT = 1.2 V, fSW = 480 kHz
85 %
VOUT = 0.8 V, fSW = 480 kHz
80 %
VOUT = 3.3V, fSW = 630 kHz
95 %
VOUT = 2.5V, fSW = 530 kHz
93 %
VOUT = 1.8V, fSW = 480 kHz
91 %
VOUT = 1.2V, fSW = 480 kHz
89 %
VOUT = 0.8V, fSW = 480 kHz
85 %
VOUT = 0.6V, fSW = 250 kHz
83 %
20 MHz bandwith
VINH-H
VINH-L
II(stby)
Inhibit Control
1.0 A/µs load step
from 50 to 100% IOUT(max)
Recovery time
VOUT over/undershoot
1.30
Inhibit Low Voltage
–0.3
-3.4
Input standby current
INH pin to AGND
2
I(PWRGD) = 2 mA
Over VIN and IOUT ranges, RT/CLK pin OPEN
fCLK
Synchronization frequency
VCLK-H
CLK High-Level
VCLK-L
CLK Low-Level
DCLK
CLK Duty cycle
Thermal Shutdown
4
Fault
91%
Good
106%
Ceramic
μA
4
µA
V
kHz
250
780
kHz
2.0
5.5
V
0.8
V
44
250
80%
175
°C
10
°C
(5)
µF
68 (5)
47
Non-ceramic
μA
0.3
160
Non-ceramic
V
300
200
Thermal shutdown hysteresis
Equivalent series resistance (ESR)
(6)
109%
Thermal shutdown
Ceramic
(5)
94%
Fault
20%
External input capacitance
External output capacitance
Good
CLK Control
(4)
1.05
-1.15
VOUT falling
mV
Open
INH > 1.26 V
Switching frequency
(4)
µs
INH < 1.1 V
PWRGD Low Voltage
COUT
A
80
INH Hysteresis current
fSW
CIN
11
INH Input current
PWRGD Thresholds
UNIT
mVPP
60
Inhibit High Voltage
VOUT rising
Power
Good
MAX
30
Overcurrent threshold
Transient response
TYP
VOUT = 5 V, fSW = 780 kHz
(6)
200
1500
220 (6)
5000
35
µF
mΩ
This control pin has an internal pullup. If this pin is left open circuit, the device operates when input power is applied. A small lowleakage MOSFET is recommended for control. See the application section for further guidance.
A minimum of 100µF of polymer tantalum and/or ceramic external capacitance is required across the input (VIN and PVIN connected)
for proper operation. Locate the capacitor close to the device. See Table 4 for more details. When operating with split VIN and PVIN
rails, place 4.7µF of ceramic capacitance directly at the VIN pin.
The amount of required output capacitance varies depending on the output voltage (see Table 3 ). The amount of required capacitance
must include at least 1x 47µF 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.
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SNVS993B – JUNE 2013 – REVISED APRIL 2018
5 Device Information
Functional Block Diagram
Thermal Shutdown
PWRGD
INH/UVLO
PWRGD
Logic
VSENSE+
Shutdown
Logic
OCP
VIN
VIN
UVLO
PVIN
VADJ
+
+
SS/TR
VREF
PH
Comp
STSEL
Current
Share
ISHARE
RT/CLK
Power
Stage
and
Control
Logic
VOUT
OSC
w/PLL
PGND
AGND
LMZ31506
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SNVS993B – JUNE 2013 – REVISED APRIL 2018
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Pin Descriptions
TERMINAL
NAME
DESCRIPTION
NO.
1
2
AGND
34
Zero VDC reference for the analog control circuitry. Connect AGND to PGND at a single point. Connect near
the output capacitors. See Figure 43 for a recommended layout.
45
8
INH/UVLO
ISHARE
9
5
Inhibit and UVLO adjust pin. Use an open drain or open collector output logic to control the INH function. A
resistor divider between this pin, AGND and VIN adjusts the UVLO voltage. Tie both pins together when
using this control.
Current share pin. Connect this pin to other LMZ31506 device's ISHARE pin when paralleling multple
LMZ31506 devices. When unused, treat this pin as a Do Not Connect (DNC) and leave it isolated from all
other signals or ground.
3
4
15
16
18
19
DNC
20
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.
22
23
30
31
32
36
PGND
37
Common ground connection for the PVIN, VIN, and VOUT power connections. See Figure 43 for a
recommended layout.
38
10
11
12
PH
13
Phase switch node. These pins should be connected to a small copper island under the device for thermal
relief. Do not connect any external component to this pin or tie it to a pin of another function.
14
17
46
PWRGD
33
Power good fault pin. Asserts low if the output voltage is out of range. A pull-up resistor is required.
39
PVIN
40
Input switching voltage. This pin supplies voltage to the power switches of the converter. See Figure 43 for a
recommended layout.
41
RT/CLK
35
This pin automatically selects between RT mode and CLK mode. A timing resistor adjusts the switching
frequency of the device. In CLK mode, the device synchronizes to an external clock.
SENSE+
44
Remote sense connection. Connect this pin to VOUT at the load for improved regulation. This pin must be
connected to VOUT at the load, or at the module pins.
SS/TR
6
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
7
Slow-start or track feature select. Connect this pin to AGND to enable the internal SS capacitor with a SS
interval of approximately 1.1 ms. Leave this pin open to enable the TR feature.
VADJ
43
Connecting a resistor between this pin and AGND sets the output voltage.
VIN
42
Input bias voltage pin. Supplies the control circuitry of the power converter. See Figure 43 for a
recommended layout.
6
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Pin Descriptions (continued)
TERMINAL
NAME
DESCRIPTION
NO.
21
24
25
VOUT
26
27
Output voltage. Connect output capacitors between these pins and PGND.
28
29
47
38 PGND
39 PVIN
40 PVIN
41 PVIN
42 VIN
43 VADJ
44 SENSE+
RUQ PACKAGE
47 PIN
TOP VIEW
AGND 1
37
PGND
AGND 2
36
PGND
DNC 3
35
RT/CLK
34
AGND
ISHARE 5
33
PWRGD
SS/TR 6
32
DNC
STSEL 7
31
DNC
INH/UVLO 8
30
DNC
INH/UVLO 9
29
VO
28
VO
27
VO
26
VO
PH 13
25
VO
PH 14
24
VO
DNC 15
23
DNC
DNC 4
45
AGND
PH 10
PH 11
DNC 22
VO 21
DNC 20
DNC 19
DNC 18
47
VO
PH 17
DNC 16
PH 12
46
PH
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SNVS993B – JUNE 2013 – REVISED APRIL 2018
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6 Typical Characteristics (PVIN = VIN = 12 V)
100
95
90
85
80
75
70
65
60
55
50
45
40
90
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
80
Output Voltage Ripple (mV)
Efficiency (%)
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 double-sided PCB with 1 oz. copper. Applies to Figure 4.
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2V, fSW = 480 kHz
VOUT = 0.8V, fSW = 330 kHz
0
1
2
3
4
Output Current (A)
5
70
60
50
40
30
20
10
0
6
0
Figure 1. Efficiency vs. Output Current
2
3
4
Output Current (A)
6
G000
90
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
2
80
Ambient Temperature (°C)
2.5
1.5
1
0.5
70
60
50
40
30
All Output Voltages
20
0
1
2
3
4
Output Current (A)
5
6
0
2
120
30
90
20
60
10
30
0
0
−10
−30
−20
−60
−40
1000
5
6
G000
Figure 4. Safe Operating Area
40
−30
3
4
Output Current (A)
G000
Figure 3. Power Dissipation vs. Output Current
Gain (dB)
1
Natural Convection
Gain
Phase
Phase (°)
0
5
Figure 2. Voltage Ripple vs. Output Current
3
Power Dissipation (W)
1
G000
−90
10000
Frequency (Hz)
100000
−120
400000
G000
Figure 5. VOUT= 1.8 V, IOUT= 6 A, COUT1= 200 µF ceramic, fSW= 480 kHz
8
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7 Typical Characteristics (PVIN = VIN = 5 V)
100
95
90
85
80
75
70
65
60
55
50
45
40
60
Output Voltage Ripple (mV)
Efficiency (%)
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 double-sided PCB with 1 oz. copper. Applies to Figure 9.
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
VOUT = 0.6V, fSW = 250 kHz
0
1
2
3
4
Output Current (A)
5
40
30
20
10
0
6
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
VOUT = 0.6 V, fSW = 250 kHz
50
0
Figure 6. Efficiency vs. Output Current
2
3
4
Output Current (A)
6
G000
90
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
VOUT = 0.6 V, fSW = 250 kHz
1.5
80
Ambient Temperature (°C)
2
1
0.5
70
60
50
40
30
All Output Voltages
20
0
1
2
3
4
Output Current (A)
5
6
0
2
120
30
90
20
60
10
30
0
0
−10
−30
−20
−60
−40
1000
5
6
G000
Figure 9. Safe Operating Area
40
−30
3
4
Output Current (A)
G000
Figure 8. Power Dissipation vs. Output Current
Gain (dB)
1
Natural Convection
Gain
Phase
Phase (°)
0
5
Figure 7. Voltage Ripple vs. Output Current
2.5
Power Dissipation (W)
1
G000
−90
10000
Frequency (Hz)
100000
−120
400000
G000
Figure 10. VOUT= 1.8 V, IOUT= 6 A, COUT1= 200 µF ceramic, fSW=480 kHz
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8 Typical Characteristics (PVIN = 12 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 double-sided PCB with 1 oz. copper. Applies to Figure 14 and Figure 15.
90
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2V, fSW = 480 kHz
VOUT = 0.8V, fSW = 330 kHz
0
1
2
3
4
Output Current (A)
5
70
60
50
40
30
20
10
0
6
0
1
G000
Figure 11. Efficiency vs. Output Current
2
3
4
Output Current (A)
G000
1.5
1
70
60
50
40
0.5
30
0
20
VOUT< 5.0 V
0
1
2
3
4
Output Current (A)
5
6
0
1
Natural Convection
2
3
4
Output Current (A)
5
6
G000
G000
Figure 14. Safe Operating Area
Figure 13. Power Dissipation vs. Output Current
90
40
120
80
30
90
20
60
10
30
0
0
Gain (dB)
70
60
50
40
30
20
0
1
2
3
4
Output Current (A)
5
6
G000
Figure 15. Safe Operating Area
−30
−20
−60
−30
100 LFM
Natural Convection
VOUT = 5.0 V
−10
−40
1000
Gain
Phase
Phase (°)
2
80
Ambient Temperature (°C)
2.5
Ambient Temperature (°C)
6
90
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
3
10
5
Figure 12. Voltage Ripple vs. Output Current
3.5
Power Dissipation (W)
VOUT = 5.0 V, fSW = 780 kHz
VOUT = 3.3 V, fSW = 630 kHz
VOUT = 2.5 V, fSW = 480 kHz
VOUT = 1.8 V, fSW = 480 kHz
VOUT = 1.2 V, fSW = 480 kHz
VOUT = 0.8 V, fSW = 480 kHz
80
Output Voltage Ripple (mV)
Efficiency (%)
100
95
90
85
80
75
70
65
60
55
50
45
40
−90
10000
Frequency (Hz)
100000
−120
400000
G000
Figure 16. VOUT= 2.5 V, IOUT= 6 A, COUT1= 200 µF ceramic,
fSW= 480 kHz
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9 Application Information
9.1 Adjusting the Output Voltage
The VADJ control sets the output voltage of the LMZ31506. 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 43) and AGND (pin 45). The SENSE+ pin (pin 44) 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 35) and AGND (pin 34). Table 1 gives the standard external RSET resistor for a
number of common bus voltages, along with the required 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)
261
261
200
200
165
121
86.6
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
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
0.6
open
open
250
3.1
0.348
140
580
0.7
8.66
590
330
3.2
0.332
140
580
0.8
4.32
590
330
3.3
0.316
121
630
0.9
2.87
261
430
3.4
0.309
121
630
1.0
2.15
261
430
3.5
0.294
121
630
1.1
1.74
261
430
3.6
0.287
121
630
1.2
1.43
200
480
3.7
0.280
121
630
1.3
1.24
200
480
3.8
0.267
107
680
1.4
1.07
200
480
3.9
0.261
107
680
1.5
0.953
200
480
4.0
0.255
107
680
1.6
0.866
200
480
4.1
0.243
107
680
1.7
0.787
200
480
4.2
0.237
95.3
730
1.8
0.715
200
480
4.3
0.232
95.3
730
1.9
0.665
200
480
4.4
0.226
95.3
730
2.0
0.619
200
480
4.5
0.221
95.3
730
2.1
0.576
200
480
4.6
0.215
95.3
730
2.2
0.536
200
480
4.7
0.210
95.3
730
2.3
0.511
200
480
4.8
0.205
86.6
780
2.4
0.475
200
480
4.9
0.200
86.6
780
2.5
0.453
200
480
5.0
0.196
86.6
780
2.6
0.432
165
530
5.1
0.191
86.6
780
2.7
0.412
165
530
5.2
0.187
86.6
780
2.8
0.392
165
530
5.3
0.182
86.6
780
2.9
0.374
165
530
5.4
0.178
86.6
780
3.0
0.357
140
580
5.5
0.174
86.6
780
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9.2 Capacitor Recommendations for the LMZ31506 Power Supply
9.2.1 Capacitor Technologies
9.2.1.1 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.
9.2.1.2 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.
9.2.1.3 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.
9.2.2 Input Capacitor
The LMZ31506 requires a minimum input capacitance of 100 μF of ceramic and/or polymer-tantalum capacitors.
The ripple current rating of the capacitor must be at least 450 mArms. Table 4 includes a preferred list of
capacitors by vendor.
9.2.3 Output Capacitor
The required output capacitance is determined by the output voltage of the LMZ31506. See Table 3 for the
amount of required capacitance. The required output capacitance must be comprised of all ceramic capacitors.
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. See Table 5 for typical transient response values for several output voltage, input voltage and
capacitance combinations. Table 4 includes a preferred list of capacitors by vendor.
Table 3. Required Output Capacitance
VOUT RANGE (V)
12
MINIMUM REQUIRED COUT (µF)
MIN
MAX
0.6
< 0.8
400 µF ceramic
0.8
< 1.2
300 µF ceramic
1.2
< 3.0
200 µF ceramic
3.0
< 4.0
100 µF ceramic
4.0
5.5
47 µF ceramic
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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
16
22
2
TDK
X5R
C3225X5R0J476K
6.3
47
2
Murata
X5R
GRM32ER60J476M
6.3
47
2
Sanyo
POSCAP
16TQC68M
16
68
50
Kemet
T520
T520V107M010ASE025
10
100
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
Please verify availability of capacitors identified in this table.
RoHS, Lead-free and Material Details
Please consult capacitor suppliers regarding material composition, RoHS status, lead-free status, and manufacturing process
requirements.
Maximum ESR @ 100kHz, 25°C.
9.3 Transient Response
Table 5. Output Voltage Transient Response
CIN1 = 47 µF CERAMIC, CIN2 = 220 µF POLYMER-TANTALUM
VOLTAGE DEVIATION (mV)
RECOVERY TIME
(µs)
VOUT (V)
VIN (V)
COUT1 Ceramic
COUT2 BULK
2 A LOAD STEP,
(1 A/µs)
3 A LOAD STEP,
(1 A/µs)
0.6
5
400 µF
330 µF
20
30
120
300 µF
220 µF
25
35
140
300 µF
330 µF
20
30
140
300 µF
220 µF
30
35
140
300 µF
330 µF
25
30
140
200 µF
100 µF
40
50
150
200 µF
220 µF
35
45
150
200 µF
100 µF
35
45
150
200 µF
220 µF
30
40
150
200 µF
-
65
85
160
200 µF
100 µF
55
96
160
200 µF
-
55
80
160
200 µF
100 µF
50
75
160
5
100 µF
100 µF
90
140
180
12
100 µF
100 µF
85
125
180
5
0.8
12
5
1.2
12
5
1.8
12
3.3
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9.4 Transient Waveforms
14
Figure 17. PVIN = 5V, VOUT = 0.6V, 2A Load Step
Figure 18. PVIN = 5V, VOUT = 0.8V, 2A Load Step
Figure 19. PVIN = 12V, VOUT = 1.2V, 2A Load Step
Figure 20. PVIN = 5V, VOUT = 1.2V, 2A Load Step
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Transient Waveforms (continued)
Figure 21. PVIN = 12V, VOUT = 1.8V, 2A Load Step
Figure 22. PVIN = 5V, VOUT = 1.8V, 2A Load Step
9.5 Application Schematics
LMZ31506
VIN
VIN / PVIN
4.5 V to 14.5 V
PWRGD
PVIN
+
CIN2
68 F
CIN1
47 F
VOUT
1.8 V
SENSE+
INH/UVLO
VOUT
SS/TR
+
COUT1
4x 47 F
COUT2
220 F
RT/CLK
RRT
200 k
VADJ
RSET
715
STSEL AGND PGND
Figure 23. Typical Schematic
PVIN = VIN = 4.5 V to 14.5 V, VOUT = 1.8 V
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Application Schematics (continued)
LMZ31506
VIN
VIN / PVIN
4.5 V to 14.5 V
PWRGD
PVIN
+
CIN2
68 F
CIN1
47 F
VOUT
3.3 V
SENSE+
INH/UVLO
VOUT
COUT1 +
2x 47 F
SS/TR
COUT2
100 F
RT/CLK
VADJ
RRT
121 k
RSET
316
STSEL AGND PGND
Figure 24. Typical Schematic
PVIN = VIN = 4.5 V to 14.5 V, VOUT = 3.3 V
VIN
4.5 V to 14.5 V
CIN3
4.7 F
VIN
LMZ31506
PVIN
3.3 V
+
PWRGD
PVIN
CIN2
68 F
CIN1
47 F
VOUT
1.2 V
SENSE+
INH/UVLO
VOUT
SS/TR
COUT1 +
4x 47 F
COUT2
330 F
RT/CLK
RRT
200 k
VADJ
RSET
1.43 k
STSEL AGND PGND
Figure 25. Typical Schematic
PVIN = 3.3 V, VIN = 4.5 V to 14.5 V, VOUT = 1.2 V
16
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9.6 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMZ31506 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.
9.7 VIN and PVIN Input Voltage
The LMZ31506 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 14.5 V. If using the
VIN pin separately from the PVIN pin, the VIN pin must be between 4.5 V and 14.5 V, and the PVIN pin can
range from as low as 1.6 V to 14.5 V. A voltage divider connected to the INH/UVLO pin can adjust the either
input voltage UVLO appropriately. See the Programmable Undervoltage Lockout (UVLO) section of this
datasheet for more information.
9.8 3.3-V Input Operation
Applications operating from 3.3 V must provide at least 4.5 V for VIN. See application note, SLVA561 for help
creating 5 V from 3.3 V using a small, simple charge pump device.
9.9 Power Good (PWRGD)
The PWRGD pin is an open drain output. Once the voltage on the SENSE+ pin is between 94% and 106% of the
set voltage, the PWRGD pin pull-down is released and the pin floats. The recommended pull-up 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 4.5V. The PWRGD pin is pulled low when the voltage on SENSE+ is
lower than 91% or greater than 109% 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.
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9.10 Parallel Operation
Up to six LMZ31506 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
LMZ31506 device. A typical LMZ31506 parallel schematic is shown in Figure 26. Refer to application note,
SLVA574 for information and design help when paralleling multiple LMZ31506 devices.
47µF
Voltage
Supervisor
VIN
PVIN
47µF
CSS
AGND
STSEL
VADJ
SS/TR
CSH
INH
Control
715 Ω
PWRGD
SENSE+
VOUT
LMZ31506
100µF
PGND
AGND
RRT
200kΩ
STSEL
100µF
RT/CLK
100µF 330µF
RSET
VADJ
5V
SS/TR
RRT
200kΩ
100µF
INH/UVLO
ISHARE
Sync Freq
480KHz
VOUT
LMZ31506
RT/CLK
VO = 1.8V
SENSE+
INH/UVLO
ISHARE
220µF
PWRGD
VIN
PVIN
PGND
VIN = 12V
Figure 26. Typical LMZ31506 Parallel Schematic
18
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9.11 Power-Up Characteristics
When configured as shown in the front page schematic, the LMZ31506 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. The soft-start circuitry introduces a short time delay from the point that a valid input voltage is
recognized. Figure 27 shows the start-up waveforms for a LMZ31506, operating from a 5-V input (PVIN=VIN)
and with the output voltage adjusted to 1.8 V. Figure 28 shows the start-up waveforms for a LMZ31506 starting
up into a pre-biased output voltage. The waveforms were measured with a 3-A constant current load.
Figure 27. Start-Up Waveforms
Figure 28. Start-up into Pre-bias
9.12 Pre-Biased Start-Up
The LMZ31506 has been designed to prevent discharging a pre-biased output. During monotonic pre-biased
startup, the LMZ31506 does not allow current to sink until the SS/TR pin voltage is higher than 1.4 V.
9.13 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.
9.14 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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9.15 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 pull-up 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.
Figure 29 shows the typical application of the inhibit function. The Inhibit control has its own internal pull-up to
VIN potential. An open-collector or open-drain device is recommended to control this input.
Turning Q1 on applies a low voltage to the inhibit control (INH) pin and disables the output of the supply, shown
in Figure 30. If Q1 is turned off, the supply executes a soft-start power-up sequence, as shown in Figure 31. A
regulated output voltage is produced within 3 ms. The waveforms were measured with a 3-A constant current
load.
INH/UVLO
Q1
INH
Control
AGND
STSEL
Figure 29. Typical Inhibit Control
Figure 31. Inhibit Turn-On
Figure 30. Inhibit Turn-Off
20
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9.16 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 1.1 ms. Adding additional capacitance between the SS pin and AGND increases
the slow start time. Table 6 shows an additional SS capacitor connected to the SS/TR pin and the STSEL pin
connected to AGND. See Table 6 below for SS capacitor values and timing interval.
SS/TR
CSS
(Optional)
AGND
STSEL
Figure 32. Slow-Start Capacitor (CSS) and STSEL Connection
Table 6. Slow-Start Capacitor Values and Slow-Start Time
CSS (pF)
open
2200
4700
10000
15000
22000
25000
SS Time (msec)
1.1
1.9
2.8
4.6
6.4
8.8
9.8
9.17 Overcurrent Protection
For protection against load faults, the LMZ31506 incorporates output overcurrent protection. Applying a load that
exceeds the regulator's overcurrent threshold 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 33. 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. Once the fault is removed, the module automatically recovers and returns to normal
operation as shown in Figure 34.
Figure 33. Overcurrent Limiting
Figure 34. Removal of Overcurrent Condition
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9.18 Synchronization (CLK)
An internal phase locked loop (PLL) has been implemented to allow synchronization between 250 kHz and
780 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 0.8 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 .
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 th 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
250 kHz to 780 kHz
RT/CLK
RRT
AGND
Figure 35. CLK/RT Configuration
The synchronization frequency must be selected based on the output voltages of the devices being
synchronized. Table 7 shows the allowable frequencies for a given range of output voltages. For the most
efficient solution, always synchronize to the lowest allowable frequency. For example, an application requires
synchronizing three LMZ31506 devices with output voltages of 1.2 V, 1.8 V and 3.3 V, all powered from
PVIN = 12 V. Table 7 shows that all three output voltages should be synchronized to 630 kHz.
Table 7. Synchronization Frequency vs Output Voltage
22
PVIN = 12 V
PVIN = 5 V
VOUT RANGE (V)
VOUT RANGE (V)
SYNCHRONIZATION
FREQUENCY (kHz)
RRT (kΩ)
MIN
MAX
MIN
MAX
250
open
0.6
1.0
0.6
1.3
280
1100
0.6
1.2
0.6
1.6
330
590
0.6
1.5
0.6
4.5
380
357
0.7
1.7
0.6
4.5
430
261
0.8
2.1
0.6
4.5
480
200
0.9
2.5
0.6
4.5
530
165
1.0
2.9
0.6
4.5
580
140
1.1
3.2
0.6
4.5
630
121
1.2
3.7
0.6
4.5
680
107
1.3
4.1
0.6
4.5
730
95.3
1.4
4.7
0.6
4.5
780
86.6
1.5
5.5
0.6
4.5
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9.19 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 36 using two LMZ31506 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 37 shows sequential turn-on waveforms of two LMZ31506 devices.
INH/UVLO
VOUT1
VOUT
STSEL
PWRGD
INH/UVLO
VOUT2
VOUT
STSEL
PWRGD
Figure 36. Sequencing Schematic
Figure 37. Sequencing Waveforms
Simultaneous power supply sequencing can be implemented by connecting the resistor network of R1 and R2
shown in Figure 38 to the output of the power supply that needs to be tracked or to another voltage reference
source. Figure 39 shows simultaneous turn-on waveforms of two LMZ31506 devices. Use Equation 2 and
Equation 3 to calculate the values of R1 and R2.
R1 =
(VOUT2 ´ 12.6 )
0.6
R2 =
(kW )
(2)
0.6 ´ R1
(kW )
V
( OUT2 - 0.6 )
(3)
VOUT1
VOUT
INH/UVLO
STSEL
SS/TR
VOUT2
VOUT
INH/UVLO
R1
STSEL
SS/TR
R2
Figure 38. Simultaneous Tracking Schematic
Figure 39. Simultaneous Tracking Waveforms
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9.20 Programmable Undervoltage Lockout (UVLO)
The LMZ31506 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 40 or Figure 41. 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 40. Adjustable VIN UVLO
Figure 41. 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 ≥ 4.5V. Figure 42 shows the
PVIN UVLO configuration. Use Table 9 to select RUVLO1 and RUVLO2 for PVIN. If PVIN UVLO is set for less than
3.0 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 42. Adjustable PVIN Undervoltage Lockout, (VIN ≥4.5 V)
Table 9. Standard Resistor Values for Adjusting PVIN UVLO, (VIN ≥4.5 V)
PVIN UVLO (V)
24
2.0
2.5
3.0
3.5
4.0
4.5
RUVLO1 (kΩ)
68.1
68.1
68.1
68.1
68.1
68.1
RUVLO2 (kΩ)
95.3
60.4
44.2
34.8
28.7
24.3
Hysteresis (mV)
300
315
335
350
365
385
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For higher PVIN UVLO voltages see
Table UV for resistor values
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9.21 Layout Considerations
To achieve optimal electrical and thermal performance, an optimized PCB layout is required. Figure 43 and
Figure 44 show two layers of 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.
• Place a dedicated AGND copper area beneath the LMZ31506.
• Isolate the PH copper area from the VOUT copper area using the AGND copper area.
• Connect the AGND and PGND copper area at one point; see AGND to PGND connection point in Figure 43.
• Place RSET, RRT, and CSS as close as possible to their respective pins.
• Use multiple vias to connect the power planes to internal layers.
SENSE+
Via
SENSE+
Via
VOUT
COUT3
PGND
Plane
COUT2
COUT1
Vias to
Topside
PGND
Copper
RRT
PGND
AGND to PGND
connection
CIN1
CIN2
Vias to
Topside
AGND
Copper
AGND
AGND
Plane
PH
SENSE+
Via
RSET
VIN/PVIN
SENSE+
Via
CSS
Figure 43. Typical Top-Layer Recommended Layout
Figure 44. Typical GND-Layer Recommended Layout
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9.22 EMI
The LMZ31506 is compliant with EN55022 Class B radiated emissions. Figure 46 and Figure 45 show typical
examples of radiated emissions plots for the LMZ31506 operating from 5V and 12V respectively. Both graphs
include the plots of the antenna in the horizontal and vertical positions.
Figure 45. Radiated Emissions 5-V Input, 1.8-V Output, 6-A
Load (EN55022 Class B)
26
Figure 46. Radiated Emissions 12-V Input, 1.8-V Output, 6A Load (EN55022 Class B)
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10 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (June 2017) to Revision B
Page
•
Added WEBENCH® design links for the LMZ31506.............................................................................................................. 1
•
Increased the peak reflow temperature and maximum number of reflows to JEDEC specifications for improved
manufacturability..................................................................................................................................................................... 2
•
Added Device Support section ............................................................................................................................................. 28
•
Added Mechanical, Packaging, and Orderable Information section .................................................................................... 29
Changes from Original (July 2013) to Revision A
•
Page
Added peak reflow and maximum number of reflows information ........................................................................................ 2
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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 LMZ31506 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 Community Resources
The following links connect to TI community resources. Linked contents are 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.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.5 Trademarks
E2E is a trademark 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.
28
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11.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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
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
LMZ31506RUQR
B1QFN
RUQ
47
500
330.0
24.4
9.35
15.35
3.1
16.0
24.0
Q1
LMZ31506RUQT
B1QFN
RUQ
47
250
330.0
24.4
9.35
15.35
3.1
16.0
24.0
Q1
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TAPE AND REEL BOX DIMENSIONS
Width (mm)
L
W
30
H
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMZ31506RUQR
B1QFN
RUQ
47
500
383.0
353.0
58.0
LMZ31506RUQT
B1QFN
RUQ
47
250
383.0
353.0
58.0
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PACKAGE OPTION ADDENDUM
www.ti.com
4-Jun-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LMZ31506RUQR
ACTIVE
B1QFN
RUQ
47
500
RoHS Exempt
& Green
NIPDAU
Level-3-245C-168 HR
-40 to 85
LMZ31506
LMZ31506RUQT
ACTIVE
B1QFN
RUQ
47
250
RoHS Exempt
& Green
NIPDAU
Level-3-245C-168 HR
-40 to 85
LMZ31506
(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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