LMR34215-Q1
SNVSBA9B – MAY 2019 – REVISEDLMR34215-Q1
NOVEMBER 2020
SNVSBA9B – MAY 2019 – REVISED NOVEMBER 2020
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LMR34215-Q1 4.2-V to 42-V, 1.5-A Ultra-Small Synchronous Step-Down Converter
1 Features
2 Applications
•
•
•
•
•
•
•
•
•
•
•
AEC-Q100-qualified for automotive applications:
– Temperature grade 1: –40°C to +125°C, TA
Functional Safety-Capable
– Documentation available to aid functional safety
system design
Designed for automotive applications
– Junction temperature range –40°C to +150°C
– 0.4-V dropout with 1.5-A load (typical)
– ±1.5% reference voltage tolerance
– 5-V fixed-output, adjustable output voltage
options
Suited for scalable power supplies
– Pin compatible with:
• LMR36015-Q1, LMR36006-Q1 (60 V, 0.6 A,
or 1.5 A)
• LMR33630-Q1, LMR33620-Q1 (36 V, 2 A, or
3 A)
– 400-kHz, 2.1-MHz frequency options
Integration reduces solution size and cost
– Small, 2-mm × 3-mm VQFN package with
wettable flanks
– Few external components
Low power dissipation across load spectrum
– 93% efficiency at 400 kHz (12 VIN, 5 VOUT, 1 A)
– Increased light load efficiency in PFM
– Low operating quiescent current of 24 µA
Optmized for ultra low EMI requirements
– Meets CISPR25 class 5 standard
– Hotrod™ package minimizes switch node
ringing
– Parallel input path minimizes parasitic
inductance
– Spread spectrum reduces peak emissions
ADAS camera module
Head-up display
Body control module
General purpose wide VIN power supplies
3 Description
The LMR34215-Q1 regulator is an easy-to-use,
synchronous, step-down DC/DC converter. With
integrated high-side and low-side power MOSFETs,
output current is delivered over a wide input voltage
range of 4.2 V to 42 V.
The LMR34215-Q1 uses peak-current-mode control
to provide optimal efficiency and output voltage
accuracy. Precision enable gives flexibility by enabling
a direct connection to the wide input voltage or
precise control over device start-up and shutdown.
The power-good flag, with built-in filtering and delay,
offers a true indication of system status eliminating
the requirement for an external supervisor.
Device Information
PACKAGE(1)
PART NUMBER
LMR34215-Q1
(1)
BODY SIZE (NOM)
VQFN-HR (12)
2.00 mm × 3.00 mm
For all available packages, see the orderable addendum at
the end of the data sheet.
BOOT
VIN
VIN
CIN
CBOOT
EN
VOUT
SW
L1
COUT
PGND
LMR34215-Q1
PG
VCC
CVCC
FB
AGND
Simplified Schematic
An©IMPORTANT
NOTICEIncorporated
at the end of this data sheet addresses availability, warranty, changes, use in
safety-critical
applications,
Copyright
2020 Texas Instruments
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Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Device Comparison Table...............................................3
6 Pin Configuration and Functions...................................4
7 Specifications.................................................................. 5
7.1 Absolute Maximum Ratings........................................ 5
7.2 ESD Ratings............................................................... 5
7.3 Recommended Operating Conditions.........................5
7.4 Thermal Information....................................................6
7.5 Electrical Characteristics.............................................6
7.6 Timing Requirements.................................................. 7
7.7 System Characteristics............................................... 8
7.8 Typical Characteristics................................................ 9
8 Detailed Description......................................................10
8.1 Overview................................................................... 10
8.2 Functional Block Diagram......................................... 11
8.3 Feature Description...................................................11
8.4 Device Functional Modes..........................................16
9 Power Supply Recommendations................................29
10 Layout...........................................................................30
10.1 Layout Guidelines................................................... 30
10.2 Layout Example...................................................... 32
11 Device and Documentation Support..........................34
11.1 Device Support........................................................34
11.2 Documentation Support.......................................... 34
11.3 Receiving Notification of Documentation Updates.. 34
11.4 Support Resources................................................. 34
11.5 Trademarks............................................................. 34
11.6 Electrostatic Discharge Caution.............................. 34
11.7 Glossary.................................................................. 34
12 Mechanical, Packaging, and Orderable
Information.................................................................... 35
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (October 2019) to Revision B (October 2020)
Page
• Added functional safety bullet to the Features ...................................................................................................1
• Updated the numbering format for tables, figures and cross-references throughout the document...................1
Changes from Revision * (May 2019) to Revision A (October 2019)
Page
• Added EMI description to the Features ............................................................................................................. 1
• Replaced Figure 9-19 with the correct graph....................................................................................................26
2
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5 Device Comparison Table
ORDERABLE PART
NUMBER
OUTPUT VOLTAGE
SPREAD
SPECTRUM
FPWM
fSW
PACKAGE QUANTITY
LMR34215FAQRNXTQ1
Adjustable
No
Yes
400 kHz
250
LMR34215FAQRNXRQ1
Adjustable
No
Yes
400 kHz
3000
LMR34215SC5QRNXTQ1
5-V fixed
Yes
No
2.1 MHz
250
LMR34215SC5QRNXRQ1
5-V fixed
Yes
No
2.1 MHz
3000
LMR34215FSC5RNXTQ1
5-V fixed
Yes
Yes
2.1 MHz
250
LMR34215FSC5RNXRQ1
5-V fixed
Yes
Yes
2.1 MHz
3000
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6 Pin Configuration and Functions
SW
12
5
PGND 1
11 PGND
10 VIN
VIN 2
NC
3
9 EN
BOOT
4
8 PG
5
6
7
VCC AGND FB
Figure 6-1. 12-Pin VQFN-HR RNX Package (Top View)
Table 6-1. Pin Functions
NO.
NAME
TYPE
DESCRIPTION
1, 11
PGND
G
Power ground terminal. Connect to system ground and AGND. Connect to CIN with short wide traces.
2, 10
VIN
P
Input supply to regulator. Connect to CIN with short wide traces.
3
NC
—
Connect the SW pin to NC on the PCB. This simplifies the connection from the CBOOT capacitor to the
SW pin. This pin has no internal connection to the regulator.
4
BOOT
P
Bootstrap supply voltage for internal high-side driver. Connect a high-quality 100-nF capacitor from this
pin to the SW pin. Connect the SW pin to NC on the PCB. This simplifies the connection from the CBOOT
capacitor to the SW pin.
5
VCC
P
Internal 5-V LDO output. Used as supply to internal control circuits. Do not connect to external loads.
Can be used as logic supply for power-good flag. Connect a high-quality 1-µF capacitor from this pin to
GND.
6
AGND
G
Analog ground for regulator and system. Ground reference for internal references and logic. All electrical
parameters are measured with respect to this pin. Connect to system ground on PCB.
7
FB
A
Feedback input to regulator. Connect to tap point of feedback voltage divider. Do not float. Do not
ground.
8
PG
A
Open-drain power-good flag output. Connect to suitable voltage supply through a current limiting
resistor. High = power OK, low = power bad. Goes low when EN = Low. Can be open or grounded when
not used.
9
EN
A
Enable input to regulator. High = ON, low = OFF. Can be connected directly to VIN; Do not float.
12
SW
P
Regulator switch node. Connect to power inductor. Connect the SW pin to NC on the PCB. This
simplifies the connection from the CBOOT capacitor to the SW pin.
A = Analog, P = Power, G = Ground
4
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7 Specifications
7.1 Absolute Maximum Ratings
Over operating junction temperature range of -40°C to 150°C (unless otherwise noted)(1)
MIN
MAX
VIN to PGND
–0.3
45
V
EN to AGND
–0.3
45.3
V
FB to AGND
–0.3
5.5
V
PG to AGND
–0.3
22
V
AGND to PGND
–0.3
0.3
V
SW to PGND
–0.3
45.3
V
SW to PGND less than 10-ns negative transient
–3.5
CBOOT to SW
–0.3
5.5
VCC to AGND
–0.3
5.5
V
Junction Temperature TJ
-40
150
°C
Storage temperature, Tstg
–65
150
°C
Input voltage
Output voltage
(1)
UNIT
V
V
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under
Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
7.2 ESD Ratings
VALUE
UNIT
V(ESD)
Electrostatic
discharge
Human-body model (HBM), per AEC Q100-002(1)
HBM ESD Classification Level 2
±2500
V
V(ESD)
Electrostatic
discharge
Charged-device model (CDM), per AEC Q100-011
CDM ESD Classification Level C5
±750
V
(1)
AEC Q100-002 indicates that HBM stressing shall be in accordance with ANSI/ESDA/JEDEC JS-001 specification
7.3 Recommended Operating Conditions
Over the recommended operating junction temperature range of –40 ℃ to 150 ℃ (unless otherwise noted)(1)
MIN
MAX
4.2
42
V
EN to PGND(2)
0
42
V
PG to PGND(2)
0
18
V
IOUT
0
1.5
A
VIN to PGND
Input voltage
Output current
(1)
(2)
UNIT
Recommended operating conditions indicate conditions for which the device is intended to be functional, but do not ensure specific
performance limits. For ensured specifications, see Electrical Characteristics.
The voltage on this pin must not exceed the voltage on the VIN pin by more than 0.3 V.
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7.4 Thermal Information
LMR34215-Q1
THERMAL
METRIC(1)
RNX (VQFN-HR)
UNIT
12 PINS
RθJA
Junction-to-ambient thermal resistance
72.5
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
35.9
°C/W
RθJB
Junction-to-board thermal resistance
23.3
°C/W
ψJT
Junction-to-top characterization parameter
0.8
°C/W
ψJB
Junction-to-board characterization parameter
23.5
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
7.5 Electrical Characteristics
Limits apply over operating junction temperature (TJ ) range of –40°C to +150°C, unless otherwise stated. Minimum and
Maximum limits(1) are specified through test, design or statistical correlation. Typical values represent the most likely
parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following
conditions apply: VIN = 12V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
14
24
35
UNIT
SUPPLY VOLTAGE (VIN PIN)
IQ-nonSW
Operating quiescent current (nonswitching)(2)
VEN = 3.3 V (PFM variant only)
ISD
Shutdown quiescent current;
measured at VIN pin
VEN = 0 V
3.3
µA
µA
ENABLE (EN PIN)
VEN-VCC-H
Enable input high level for VCC output
VENABLE rising; Internal LDO turns ON
VEN-VCC-L
Enable input low level for VCC output
VENABLE falling; Internal LDO turns
OFF
VEN-VOUT-H
Enable input high level for VOUT
VENABLE rising; Switching ON
1.157
1.231
1.3
V
VEN-VOUT-HYS Enable input hysteresis for VOUT
Hysteresis below VEN-VOUT-H;
Switching OFF
45
110
175
mV
ILKG-EN
VEN = 3.3V
0.2
50
nA
4.75
5
5.25
V
Enable input leakage current
1.14
0.3
V
V
INTERNAL LDO (VCC PIN)
VCC
VCC-UVLORising
VCC-UVLOFalling
Internal VCC voltage
6 V ≤ VIN ≤ 42 V
Internal VCC undervoltage lockout
VCC rising
3.6
3.8
4.0
V
Internal VCC undervoltage lockout
VCC falling
3.1
3.3
3.5
V
4.9
5
5.1
V
0.985
1
1.015
V
VOLTAGE REFERENCE (FB PIN)
6
V5v0-Fixed
5 V Fixed Output voltage
Fixed output voltage option
VFB
Feedback voltage
Adjustable output voltage option
ILKG-5v0-Fixed
Feedback leakage current; 5v0 Fixed
VOUT = 5 V (Fixed output voltage
option only)
2.5
2.9
µA
ILKG-FB
Feedback leakage current
FB = 1 V (Adjustable output voltage
option only)
0.2
125
nA
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Limits apply over operating junction temperature (TJ ) range of –40°C to +150°C, unless otherwise stated. Minimum and
Maximum limits(1) are specified through test, design or statistical correlation. Typical values represent the most likely
parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following
conditions apply: VIN = 12V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CURRENT LIMITS AND HICCUP
ISC
High-side current limit(3)
2
2.4
2.8
A
ILS-LIMIT
Low-side current limit(3)
1.55
1.8
2.07
A
IL-ZC
Zero cross detector threshold
IPEAK-MIN
Minimum inductor peak current(3)
IL-NEG
Negative current
PFM variants only
limit(3)
FPWM variant only
0.02
A
0.45
A
–1.8
–1.4
–0.9
A
POWER GOOD (PGOOD PIN)
VPG-HIGH-UP
Power-Good upper threshold - rising
% of FB voltage
105%
107%
110%
VPG-LOW-DN
Power-Good lower threshold - falling
% of FB voltage
90%
93%
95%
VPG-HYS
Power-Good hysteresis (rising &
falling)
% of FB voltage
TPG
Power-Good rising/falling edge
deglitch delay
VPG-VALID
Minimum input voltage for proper
Power-Good function
RPG
Power-Good on-resistance
VEN = 2.5 V
RPG
Power-Good on-resistance
VEN = 0 V
2%
80
140
200
µs
2
V
80
165
Ω
35
90
Ω
OSCILLATOR
FOSC
Internal oscillator frequency
2.1-MHz variant
1.95
2.1
2.35
MHz
FOSC
Internal oscillator frequency
400-kHz variant
340
400
460
kHz
RDS-ON-HS
High-side MOSFET ON-resistance
IOUT = 0.5 A
225
435
mΩ
RDS-ON-LS
Low-side MOSFET ON-resistance
IOUT = 0.5 A
150
280
mΩ
MOSFETS
(1)
(2)
(3)
MIN and MAX limits are 100% production tested at 25℃. Limits over the operating temperature range verified through correlation using
Statistical Quality Control (SQC) methods. Limits are used to calculate Average Outgoing Quality Level (AOQL).
This is the current used by the device open loop. It does not represent the total input current of the system when in regulation.
The current limit values in this table are tested, open loop, in production. They may differ from those found in a closed loop application.
7.6 Timing Requirements
Limits apply over operating junction temperature (TJ ) range of –40°C to +150°C, unless otherwise stated. Minimum and
Maximum limits(1) are specified through test, design or statistical correlation. Typical values represent the most likely
parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following
conditions apply: VIN = 12 V.
NOM
MAX
tON-MIN
Minimum switch on-time
MIN
55
83
ns
tOFF-MIN
Minimum switch off-time
53
73
ns
tON-MAX
Maximum switch on-time
7
12
µs
tSS
Internal soft-start time
4.5
6
ms
(1)
3
UNIT
MIN and MAX limits are 100% production tested at 25℃. Limits over the operating temperature range verified through correlation using
Statistical Quality Control (SQC) methods. Limits are used to calculate Average Outgoing Quality Level (AOQL).
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7.7 System Characteristics
The following specifications apply to a typical application circuit with nominal component values. Specifications in the typical
(TYP) column apply to TJ = 25℃ only. Specifications in the minimum (MIN) and maximum (MAX) columns apply to the case
of typical components over the temperature range of TJ = –40℃ to 150℃. These specifications are not ensured by
production testing.
PARAMETER
MIN
TYP
MAX
VOUT
Adjustable output voltage regulation(1)
DMAX
Maximum switch duty cycle(2)
VHC
FB pin voltage required to trip short-circuit
hiccup mode
0.4
V
94
ms
2
ns
FPWM operation
4.2
42
–1.5%
1.5%
UNIT
Operating input voltage range
V
98%
tHC
Time between current-limit hiccup burst
tD
Switch voltage dead time
FsSS
Frequency span of spread spectrum
operation
±4
%
FrSS
Triangular spread spectrum repetition
frequency
16
kHz
TSD
Thermal shutdown temperature
Shutdown temperature
170
°C
TSD
Thermal shutdown temperature
Recovery temperature
158
°C
(1)
(2)
8
TEST CONDITIONS
VIN
Deviation in VOUT from nominal output voltage value at VIN = 24 V, IOUT = 0 A to 1.5 A
In dropout the switching frequency drops to increase the effective duty cycle. The lowest frequency is clamped at approximately: FMIN
= 1 / (tON-MAX + tOFF-MIN). DMAX = tON-MAX /(tON-MAX + tOFF-MIN).
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7.8 Typical Characteristics
Unless otherwise specified the following conditions apply: TA = 25°C. VIN = 24 V.
30
12
29
10
Shutdown Current (µA)
Quiescent Current (µA)
28
27
26
25
24
23
22
8
6
4
25C
150C
-40C
21
20
2
6
10
14
18
22
26
30
Input Voltage (V)
34
38
42
6
10
14
18
LMR3
VFB = 1 V
22
26
30
Input Voltage (V)
34
38
42
Shut
EN = 0 V
Figure 7-1. Non-Switching Input Supply Current
Figure 7-2. Shutdown Supply Current
3.2
2.2
3
2
Current (A)
Current (A)
2.8
2.6
1.8
1.6
2.4
1.4
2.2
2
-40
0
40
80
Temperature (°C)
120
1.2
-40
150
0
hs-c
VIN = 24 V
Figure 7-3. High Side Current Limit
150
ls-c
Figure 7-4. Low Side Current Limit
700
1.016
675
Peak Inductor Current (mA)
1.012
1.008
Voltage (V)
120
VIN = 24 V
1.02
1.004
1
0.996
0.992
0.988
0.984
0.98
-40
40
80
Temperature (°C)
0
40
80
Temperature (°C)
120
150
vref
650
625
600
575
550
525
500
475
5
10
IOUT = 0 A
15
20
25
30
Input Voltage (V)
VOUT = 5V
35
40
45
lmr3
ƒSW = 2100 kHz
Figure 7-5. Reference Voltage Drift
Figure 7-6. IPEAK-MIN
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8 Detailed Description
8.1 Overview
The LMR34215-Q1 is a synchronous peak-current-mode buck regulator designed for a wide variety of
applications. The regulator automatically switches modes between PFM and PWM, depending on load. At heavy
loads, the device operates in PWM at a constant switching frequency. At light loads, the mode changes to
PFMW with diode emulation allowing DCM. This reduces the input supply current and keeps efficiency high. The
device features internal loop compensation which reduces design time and requires fewer external components
than externally compensated regulators.
The LMR34215-Q1 is designed with a flip-chip or HotRod technology, greatly reducing the parasitic inductance
of pins. In addition, the layout of the device allows for reduction in the radiated noise generated by the switching
action through partial cancellation of the current generated magnetic field. As a result, the switch-node waveform
exhibits less overshoot and ringing.
2V/div
50ns/div
BW:500MHz
Figure 8-1. Switch Node Waveform
10
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8.2 Functional Block Diagram
VCC
INT. REG.
BIAS
OSCILLATOR
EN
VIN
ENABLE
LOGIC
BOOT
HS CURRENT
SENSE
1.0V
Reference
ERROR
AMPLIFIER
FB
+
-
PG
+
-
PWM
COMP.
CONTROL
LOGIC
PFM MODE
CONTROL
SW
DRIVER
LS CURRENT
SENSE
POWER GOOD
CONTROL
AGND
PGND
8.3 Feature Description
8.3.1 Power-Good Flag Output
The power-good flag function (PG output pin) of the LMR34215-Q1 can be used to reset a system
microprocessor whenever the output voltage is out of regulation. This open-drain output goes low under fault
conditions, such as current limit and thermal shutdown, as well as during normal start-up. A glitch filter prevents
false flag operation for short excursions of the output voltage, such as during line and load transients. Output
voltage excursions lasting less than t PG do not trip the power-good flag. Power-good operation can best be
understood by reference to Figure 8-2 and Figure 8-3. Note that during initial power-up, a delay of about 4 ms
(typical) is inserted from the time that EN is asserted to the time that the power-good flag goes high. This delay
only occurs during start-up and is not encountered during normal operation of the power-good function.
The power-good output consists of an open-drain NMOS, requiring an external pullup resistor to a suitable logic
supply. It can also be pulled up to either VCC or V OUT through an appropriate resistor as desired. If this function
is not needed, the PG pin must be grounded. When EN is pulled low, the flag output is also forced low. With EN
low, power good remains valid as long as the input voltage is ≥ 2 V (typical). Limit the current into this pin to ≤ 4
mA.
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VOUT
VPG-HIGH_UP (107%)
VPG-HIGH-DN (105%)
VPG-LOW-UP (95%)
VPG-LOW-DN (93%)
PG
High = Power Good
Low = Fault
Figure 8-2. Static Power-Good Operation
12
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Glitches do not cause false operation nor reset timer
VOUT
VPG-LOW-UP (95%)
VPG-LOW-DN (93%)
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