TI LM2773TL/NOPB Lm2773 low-ripple 1.8v/1.6v spread-spectrum switched capacitor step-down regulator Datasheet

LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
LM2773 Low-Ripple 1.8V/1.6V Spread-Spectrum Switched Capacitor Step-Down Regulator
Check for Samples: LM2773
FEATURES
DESCRIPTION
•
•
•
•
•
•
•
•
•
•
•
•
The LM2773 is a switched capacitor step-down
regulator that produces a selectable 1.8V or 1.6V
output. It is capable of supplying loads up to 300mA.
The LM2773 operates with an input voltage from 2.5V
to 5.5V, accommodating 1-cell Li-Ion batteries and
chargers.
1
2
Low-Noise Spread Spectrum Operation
1.8V/1.6V Selectable Output Voltage
2% Output Voltage Regulation
> 75% Efficiency in 1.8V Mode
Very Low Output Ripple: 10mV @ 300mA
Output Currents up to 300mA
2.5V to 5.5V Input Voltage Range
Shutdown Disconnects Load from VIN
1.15MHz Switching Frequency
No Inductors…Small Solution Size
Short Circuit and Thermal Protection
0.5mm pitch, DSBGA-9 (1.511 × 1.511mm ×
0.6mm)
The LM2773 utilizes a regulated charge pump with
gains of 2/3x and 1x. It has very low ripple and noise
on both the input and output due to its pre-regulated
1.15MHz (typ.) switching frequency and spread
spectrum operation. When output currents are low,
the LM2773 automatically switches to a low-ripple
PFM regulation mode to maintain high efficiency over
the entire load range.
The LM2773 is available in TI's 0.5mm pitch 9-bump
DSBGA.
APPLICATIONS
•
•
•
Power Supply for DSP's, Memory, and
Microprocessors
Mobile Phones and Pagers
Digital Cameras, Portable Music Players, and
Other Portable Electronic Devices
Typical Application Circuit
VIN = 2.5V to
5.5V
CIN
1 PF
VIN
GND
C2+
VOUT
VOUT: 1.8V or 1.6V
IOUT up to 300 mA
COUT
4.7 PF
LM2773
C1+
C1
1 PF
C2
1 PF
C2-
C1-
EN
SEL
Capacitors: 1 PF - C1005 (0402), X5R, 6.3V
4.7 PF - C1608 (0603), X5R, 6.3V
or equivalent
Figure 1.
Figure 2. LM2773 Efficiency vs.
Low-Dropout Linear Regulator (LDO) Efficiency
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2013, Texas Instruments Incorporated
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Connection Diagram
A1
A2
A3
A3
A2
A1
B1
B2
B3
B3
B2
B1
C1
C2
C3
C3
C2
C1
Top View
Bottom View
9-Bump DSBGA
See Package Number YZR0009
0.5mm Pitch 1.511mm x 1.511mm x 0.6mm
PIN DESCRIPTIONS
Pin #
Name
A1
C2-
Description
A2
VOUT
Output Voltage
A3
C1+
Flying Capacitor 1: Positive Terminal
B1
GND
Ground
B2
EN
Device Enable. Logic HIGH: Enabled, Logic LOW: Shutdown.
Flying Capacitor 2: Negative Terminal
B3
VIN
Input Voltage. Recommended VIN Operating Range = 2.5V to 5.5V.
C1
SEL
Voltage Mode Select. Logic HIGH: VOUT = 1.6V, Logic LOW: VOUT = 1.8V
C2
C1-
Flying Capacitor 1: Negative Terminal
C3
C2+
Flying Capacitor 2: Positive Terminal
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
2
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
Absolute Maximum Ratings (1) (2) (3)
VIN Pin Voltage
-0.3V to 6.0V
EN, SEL Pin Voltage
-0.3V to (VIN+0.3V) w/ 6.0V max
Continuous Power Dissipation (4)
Internally Limited
Junction Temperature (TJ-MAX)
150°C
Storage Temperature Range
-65°C to +150° C
Maximum Lead Temperature
(Soldering, 10 sec.)
265°C
ESD Rating (5)
Human Body Model:
(1)
(2)
(3)
(4)
(5)
2.5kV
Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under
which operation of the device is ensured. Operating Ratings do not imply specified performance limits. For specified performance limits
and associated test conditions, see the Electrical Characteristics tables.
If Military/Aerospace specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.
All voltages are with respect to the potential at the GND pins.
Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=150°C (typ.) and
disengages at TJ=140°C (typ.).
The Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. MIL-STD-883 3015.7
Operating Ratings (1) (2)
Input Voltage Range
2.5V to 5.5V
Recommended Load Current Range
0mA to 300mA
Junction Temperature (TJ) Range
Ambient Temperature (TA) Range
(1)
(2)
(3)
-30°C to +110°C
(3)
-30°C to +85°C
Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under
which operation of the device is ensured. Operating Ratings do not imply ensured performance limits. For specified performance limits
and associated test conditions, see the Electrical Characteristics tables.
All voltages are with respect to the potential at the GND pins.
Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 110°C), the
maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package
in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX).
Thermal Properties
Junction-to-Ambient Thermal
Resistance (θJA), DSBGA-9 Package (1)
(1)
75°C/W
Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power
dissipation exists, special care must be paid to thermal dissipation issues.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
3
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Electrical Characteristics (1) (2)
Limits in standard typeface are for TJ = 25°C. Limits in boldface type apply over the full operating junction temperature range
(-30°C ≤ TJ ≤ +110°C) . Unless otherwise noted, specifications apply to the LM2773 Typical Application Circuit (pg. 1) with:
VIN = 3.6V; V(EN) = 1.8V, V(SEL) = 0V, CIN = C1 = C2 = 1.0µF, COUT = 4.7µF. (3)
Symbol
Typ
Max
1.8V Mode Output Voltage
Regulation
2.5V ≤ VIN ≤ 5.5V
0mA ≤ IOUT ≤ 300mA
1.779
(−2%)
1.815
1.851
(+2%)
1.6V Mode Output Voltage
Regulation
V(SEL) = 1.8V
2.5V ≤ VIN ≤ 5.5V
0mA ≤ IOUT ≤ 300mA
1.587
(−2%)
1.619
1.651
(+2%)
VOUT/IOUT
Output Load Regulation
0mA ≤ IOUT ≤ 300mA
VOUT/VIN
Output Line Regulation
E
Power Efficiency
IOUT = 300mA
IQ
Quiescent Supply Current
IOUT = 0mA
See (4)
48
VR
Fixed Frequency Output Ripple
IOUT = 300mA
10
VR–PFM
PFM–Mode Output Ripple
IOUT < 40mA
12
ISD
Shutdown Current
V(EN) = 0V
0.1
0.625
µA
FSW
Switching Frequency
3.0V ≤ VIN ≤ 5.5V
1.15
1.50
MHz
ROL
Open-Loop Output Resistance
IOUT = 300mA
See (5)
ICL
Output Current Limit
tON
Turn-on Time
VIL
Logic-low Input Voltage
EN, SEL Pins
2.5V ≤ VIN ≤ 5.5V
0
0.5
V
VIH
Logic-high Input Voltage
EN, SEL Pins
2.5V ≤ VIN ≤ 5.5V
1.0
VIN
V
IIH
Logic-high Input Current
V(EN), V(SEL) = 1.8V
See (7)
IIL
Logic-low Input Current
V(EN), V(SEL) = 0V
VOUT
(1)
(2)
(3)
(4)
(5)
(6)
(7)
4
Parameter
Condition
Min
0.80
VIN = 5.5V
0V ≤ VOUT ≤ 0.2V
See (6)
Units
V
0.15
mV/mA
0.3
%/V
75
%
55
µA
mV
mV
1.0
Ω
500
mA
150
µs
5
µA
0.01
µA
All voltages are with respect to the potential at the GND pins.
Min and Max limits are specified by design, test, or statistical analysis. Typical numbers are not ensured, but do represent the most
likely norm.
CIN, COUT, C1, C2: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics.
VOUT is set to 1.9V during this test (Device is not switching).
Open loop output resistance can be used to predict output voltage when, under low VIN and high IOUT conditions, VOUT falls out of
regulation. VOUT = (Gain)VIN - (ROL x IOUT)
Under the stated conditions, the maximum input current is equal to 2/3 the maximum output current.
There are 350kΩ pull-down resistors connected internally between the EN pin and GND and the SEL pin and GND.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
BLOCK DIAGRAM
LM2773
VIN
C1+
SWITCH
ARRAY
GAIN
CONTROL
SWITCH
CONTROL
G =1,
2
C1C2+
3
C2GND
Spread
Spectrum
1.25V
Ref.
PFM
Control
Current
sense
VOUT
1.15 MHz
OSC.
EN
Enable/
Shutdown
Control
EN
Soft-Start
Ramp
0.8V
Ref.
SEL
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
5
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Typical Performance Characteristics
Unless otherwise specified: VIN = 3.6V, CIN = C1 = C2 = 1.0µF, COUT = 4.7µF, V(EN) = 1.8V, V(SEL) = 0V, TA = 25°C.
Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's).
6
Output Voltage
vs.
Input Voltage, 1.8V Mode
Output Voltage
vs.
Input Voltage, 1.6V Mode
Figure 3.
Figure 4.
Output Voltage
vs.
Output Current, 1.8V Mode
Output Voltage
vs.
Output Current, 1.6V Mode
Figure 5.
Figure 6.
Efficiency
vs.
Input Voltage, 1.8V Mode
Efficiency
vs.
Input Voltage, 1.6V Mode
Figure 7.
Figure 8.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
Typical Performance Characteristics (continued)
Unless otherwise specified: VIN = 3.6V, CIN = C1 = C2 = 1.0µF, COUT = 4.7µF, V(EN) = 1.8V, V(SEL) = 0V, TA = 25°C.
Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's).
Shutdown Supply Current
Operating Supply Current
Figure 9.
Figure 10.
Line Step 3.0V to 4.2V with Load = 300mA, 1.8V Mode
Line Step 3.0V to 4.2V with Load = 300mA, 1.6V Mode
CH1: VIN; Scale: 1V/Div, DC Coupled
CH2: VOUT; Scale: 20mV/Div, AC Coupled
Time scale: 10ms/Div
Figure 11.
Load Step 0mA to 300mA, VIN = 3.6V, 1.8V Mode
CH1: VIN; Scale: 1V/Div, DC Coupled
CH2: VOUT; Scale: 20mV/Div, AC Coupled
Time scale: 10ms/Div
Figure 12.
Load Step 300mA to 0mA, VIN = 3.6V, 1.8V Mode
CH2: VOUT; Scale: 100mV/Div
DC Coupled, Offset 1.834V
CH4: IOUT; Scale: 100mA/Div
Time scale: 4ms/Div
Figure 13.
CH2: VOUT; Scale: 100mV/Div
DC Coupled, Offset 1.834V
CH4: IOUT; Scale: 100mA/Div
Time scale: 4ms/Div
Figure 14.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
7
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Typical Performance Characteristics (continued)
Unless otherwise specified: VIN = 3.6V, CIN = C1 = C2 = 1.0µF, COUT = 4.7µF, V(EN) = 1.8V, V(SEL) = 0V, TA = 25°C.
Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's).
Load Step 0mA to 300mA, VIN = 3.6V, 1.6V Mode
Load Step 300mA to 0mA, VIN = 3.6V, 1.6V Mode
CH2: VOUT; Scale: 100mV/Div
DC Coupled, Offset 1.633V
CH4: IOUT; Scale: 100mA/Div
Time scale: 4ms/Div
Figure 15.
8
CH2: VOUT; Scale: 100mV/Div
DC Coupled, Offset 1.633V
CH4: IOUT; Scale: 100mA/Div
Time scale: 4ms/Div
Figure 16.
1.8V Mode Startup, Load = 300mA
1.6V Mode Startup, Load = 300mA, VSEL = VIN
CH1: VEN; Scale: 5V/Div, DC Coupled
CH2: VOUT; Scale: 500mV/Div, DC Coupled
Time scale: 10µs/Div
Figure 17.
CH1: VEN; Scale: 5V/Div, DC Coupled
CH2: VOUT; Scale: 500mV/Div, DC Coupled
Time scale: 10µs/Div
Figure 18.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
OPERATION DESCRIPTION
Overview
The LM2773 is a switched capacitor converter that produces a selectable 1.8V or 1.6V regulated output. The
core of the part is a highly efficient charge pump that utilizes fixed frequency pre-regulation, Pulse Frequency
Modulation, and spread spectrum to minimize conducted noise and power losses over wide input voltage and
output current ranges. A description of the principal operational characteristics of the LM2773 is detailed in the
Circuit Description, and Efficiency Performance sections. These sections refer to details in the Block Diagram.
Circuit Description
The core of the LM2773 is a two-phase charge pump controlled by an internally generated non-overlapping
clock. The charge pump operates by using external flying capacitors C1 and C2 to transfer charge from the input
to the output. The LM2773 will operate in a 1x Gain, with the input current being equal to the load current, when
the input voltage is at or below 3.5V (typ.) for 1.8V mode or 3.3V (typ.) for 1.6V mode. At input voltages above
3.5V (typ.) or 3.3V (typ.) for the respective voltage mode selected, the part utilizes a gain of 2/3x, resulting in an
input current equal to 2/3 times the load current.
The two phases of the switched capacitor switching cycle will be referred to as the "charge phase" and the
"discharge phase". During the charge phase, the flying capacitor is charged by the input supply. After half of the
switching cycle [ t = 1/(2×FSW) ], the LM2773 switches to the discharge phase. In this configuration, the charge
that was stored on the flying capacitors in the charge phase is transferred to the output.
The LM2773 uses fixed frequency pre-regulation to regulate the output voltage to 1.8V during moderate to high
load currents. The input and output connections of the flying capacitors are made with internal MOS switches.
Pre-regulation limits the gate drive of the MOS switch connected between the voltage input and the flying
capacitors. Controlling the on resistance of this switch limits the amount of charge transferred into and out of
each flying capacitor during the charge and discharge phases, and in turn helps to keep the output ripple very
low.
When output currents are low (<40mA typ.), the LM2773 automatically switches to a low-ripple Pulse Frequency
Modulation (PFM) form of regulation. In PFM mode, the flying capacitors stay in the discharge phase until the
output voltage drops below a predetermined trip point. When this occurs, the flying capacitors switch back to the
charge phase. After being charged, the flying capacitors repeat the process of staying in the discharge phase
and switching to the charge phase when necessary.
The LM2773 utilizes spread spectrum operation to distrubute the peak radiated energy of the device over a wider
frequency band, reducing electromagnetic interference (EMI). Spread spectrum is used during all modes of
operation for the LM2773.
Efficiency Performance
Charge-pump efficiency is derived in the following two ideal equations (supply current and other losses are
neglected for simplicity):
IIN = G × IOUT
E = (VOUT × IOUT) ÷ (VIN × IIN) = VOUT ÷ (G × VIN)
(1)
(2)
In the equations, G represents the charge pump gain. Efficiency is at its highest as G×VIN approaches VOUT.
Refer to the efficiency graph in the Typical Performance Characteristics section for detailed efficiency data. The
transition between the gain of 1x and 2/3x is clearly distinguished by the sharp discontinuity in the efficiency
curve.
Shutdown and Voltage Select
The LM2773 is in shutdown mode when the voltage on the enable pin (EN) is logic-low. In shutdown, the
LM2773 draws virtually no supply current. When in shutdown, the output of the LM2773 is completely
disconnected from the input. Internal feedback resistors pull the output voltage down to 0V during shutdown.
The SEL pin sets the output voltage at either 1.8V or 1.6V. A logic-low voltage on the SEL pin will place the
output of the LM2773 in the 1.6V mode, and a logic-high voltage on the SEL pin will place it into the 1.8V mode.
There are 350kΩ pull-down resistors connected internally between the EN pin and GND and the SEL pin and
GND.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
9
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Soft Start
The LM2773 employs soft start circuitry to prevent excessive input inrush currents during startup. At startup, the
output voltage gradually rises from 0V to the nominal output voltage. This occurs in 150µs (typ.). Soft-start is
engaged when the part is enabled.
Thermal Shutdown
Protection from damage related to overheating is achieved with a thermal shutdown feature. When the junction
temperature rises to 150°C (typ.), the part switches into shutdown mode. The LM2773 disengages thermal
shutdown when the junction temperature of the part is reduced to 140°C (typ.). Due to the high efficiency of the
LM2773, thermal shutdown and/or thermal cycling should not be encountered when the part is operated within
specified input voltage, output current, and ambient temperature operating ratings. If thermal cycling is seen
under these conditions, the most likely cause is an inadequate PCB layout that does not allow heat to be
sufficiently dissipated out of the DSBGA package.
Current Limit Protection
The LM2773 charge pump contains current limit protection circuitry that protects the device during VOUT fault
conditions where excessive current is drawn. Output current is limited to 500mA (typ).
APPLICATION INFORMATION
Recommended Capacitor Types
The LM2773 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors
are recommended. These capacitors are small, inexpensive and have very low equivalent series resistance
(ESR, ≤ 15mΩ typ.). Tantalum capacitors, OS-CON capacitors, and aluminum electrolytic capacitors generally
are not recommended for use with the LM2773 due to their high ESR, as compared to ceramic capacitors.
For most applications, ceramic capacitors with an X7R or X5R temperature characteristic are preferred for use
with the LM2773. These capacitors have tight capacitance tolerance (as good as ±10%) and hold their value over
temperature (X7R: ±15% over -55°C to 125°C; X5R: ±15% over -55°C to 85°C).
Capacitors with a Y5V or Z5U temperature characteristic are generally not recommended for use with the
LM2773. These types of capacitors typically have wide capacitance tolerance (+80%, -20%) and vary
significantly over temperature (Y5V: +22%, -82% over -30°C to +85°C range; Z5U: +22%, -56% over +10°C to
+85°C range). Under some conditions, a 1µF-rated Y5V or Z5U capacitor could have a capacitance as low as
0.1µF. Such detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum
capacitance requirements of the LM2773.
Net capacitance of a ceramic capacitor decreases with increased DC bias. This degradation can result in lower
capacitance than expected on the input and/or output, resulting in higher ripple voltages and currents. Using
capacitors at DC bias voltages significantly below the capacitor voltage rating will usually minimize DC bias
effects. Consult capacitor manufacturers for information on capacitor DC bias characteristics.
Capacitance characteristics can vary quite dramatically with different application conditions, capacitor types, and
capacitor manufacturers. It is strongly recommended that the LM2773 circuit be thoroughly evaluated early in the
design-in process with the mass-production capacitors of choice. This will help ensure that any such variability in
capacitance does not negatively impact circuit performance.
The table below lists some leading ceramic capacitor manufacturers.
10
Manufacturer
Contact Information
AVX
www.avx.com
Murata
www.murata.com
Taiyo-Yuden
www.t-yuden.com
TDK
www.component.tdk.com
Vishay-Vitramon
www.vishay.com
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
Output Capacitor and Output Voltage Ripple
The output capacitor in the LM2773 circuit (COUT) directly impacts the magnitude of output voltage ripple. Other
prominent factors also affecting output voltage ripple include input voltage, output current and flying capacitance.
Due to the complexity of the regulation topology, providing equations or models to approximate the magnitude of
the ripple can not be easily accomplished. But one important generalization can be made: increasing
(decreasing) the output capacitance will result in a proportional decrease (increase) in output voltage ripple.
In typical high-current applications, a 4.7µF low-ESR ceramic output capacitor is recommended. Different output
capacitance values can be used to reduce ripple, shrink the solution size, and/or cut the cost of the solution. But
changing the output capacitor may also require changing the flying capacitor and/or input capacitor to maintain
good overall circuit performance. Performance of the LM2773 with different capacitor setups in discussed in the
section Recommended Capacitor Configurations.
High ESR in the output capacitor increases output voltage ripple. If a ceramic capacitor is used at the output, this
is usually not a concern because the ESR of a ceramic capacitor is typically very low and has only a minimal
impact on ripple magnitudes. If a different capacitor type with higher ESR is used (tantalum, for example), the
ESR could result in high ripple. To eliminate this effect, the net output ESR can be significantly reduced by
placing a low-ESR ceramic capacitor in parallel with the primary output capacitor. The low ESR of the ceramic
capacitor will be in parallel with the higher ESR, resulting in a low net ESR based on the principles of parallel
resistance reduction.
Input Capacitor and Input Voltage Ripple
The input capacitor (CIN) is a reservoir of charge that aids a quick transfer of charge from the supply to the flying
capacitors during the charge phase of operation. The input capacitor helps to keep the input voltage from
drooping at the start of the charge phase when the flying capacitors are connected to the input. It also filters
noise on the input pin, keeping this noise out of sensitive internal analog circuitry that is biased off the input line.
Much like the relationship between the output capacitance and output voltage ripple, input capacitance has a
dominant, first-order effect on input ripple magnitude. Increasing (decreasing) the input capacitance will result in
a proportional decrease (increase) in input voltage ripple. Input voltage, output current, and flying capacitance
also will affect input ripple levels to some degree.
In typical high-current applications, a 1µF low-ESR ceramic capacitor is recommended on the input. Different
input capacitance values can be used to reduce ripple, shrink the solution size, and/or cut the cost of the
solution. But changing the input capacitor may also require changing the flying capacitor and/or output capacitor
to maintain good overall circuit performance. Performance of the LM2773 with different capacitor setups is
discussed below in Recommended Capacitor Configurations.
Flying Capacitors
The flying capacitors (C1, C2) transfer charge from the input to the output. Flying capacitance can impact both
output current capability and ripple magnitudes. If flying capacitance is too small, the LM2773 may not be able to
regulate the output voltage when load currents are high. On the other hand, if the flying capacitance is too large,
the flying capacitor might overwhelm the input and output capacitors, resulting in increased input and output
ripple.
In typical high-current applications, 1µF low-ESR ceramic capacitors are recommended for the flying capacitors.
Polarized capacitors (tantalum, aluminum electrolytic, etc.) must not be used for the flying capacitor, as they
could become reverse-biased during LM2773 operation.
Recommended Capacitor Configurations
The data in Table 1 can be used to assist in the selection of capacitance configurations that best balances
solution size and cost with the electrical requirements of the application.
As previously discussed, input and output ripple voltages will vary with output current and input voltage. The
numbers provided show expected ripple voltage with VIN = 3.6V and a load current of 300mA. The table offers a
first look at approximate ripple levels and provides a comparison of different capacitor configurations, but is not
intended to ensure performance. With any capacitance configuration chosen, always verify that the performance
of the ripple waveforms are suitable for the intended application. The same capacitance value must be used for
all the flying capacitors.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
11
LM2773
SNVS554A – JANUARY 2008 – REVISED MAY 2013
www.ti.com
Table 1. LM2773 Performance with Different Capacitor Configurations, 1.8V Mode
CAPACITOR
CONFIGURATION
(VIN = 3.6V)
TYPICAL
OUTPUT
RIPPLE
CIN = 1µF,
COUT = 4.7µF,
C1, C2 = 1µF
10mV
CIN = 1µF,
COUT = 2.2µF,
C1, C2 = 1µF
16mV
CIN = 0.47µF,
COUT = 4.7µF,
C1, C2 = 1µF
12mV
CIN = 0.47µF,
COUT = 3.3µF,
C1, C2 = 1µF
12mV
CIN = 0.47µF,
COUT = 3.3µF,
C1, C2 = 0.47µF
13mV
(1)
(1)
Refer to the text in the Recommended Capacitor Configurations section for detailed information on the data in this table
Layout Guidelines
Proper board layout will help to ensure optimal performance of the LM2773 circuit. The following guidelines are
recommended:
• Place capacitors as close to the LM2773 as possible, and preferably on the same side of the board as the IC.
• Use short, wide traces to connect the external capacitors to the LM2773 to minimize trace resistance and
inductance.
• Use a low resistance connection between ground and the GND pin of the LM2773. Using wide traces and/or
multiple vias to connect GND to a ground plane on the board is most advantageous.
12
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
LM2773
www.ti.com
SNVS554A – JANUARY 2008 – REVISED MAY 2013
REVISION HISTORY
Changes from Original (May 2013) to Revision A
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 12
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM2773
13
PACKAGE OPTION ADDENDUM
www.ti.com
3-May-2013
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
(2)
MSL Peak Temp
Op Temp (°C)
Top-Side Markings
(3)
(4)
LM2773TL/NOPB
ACTIVE
DSBGA
YZR
9
250
Green (RoHS
& no Sb/Br)
SNAGCU
Level-1-260C-UNLIM
DJ
LM2773TLX/NOPB
ACTIVE
DSBGA
YZR
9
3000
Green (RoHS
& no Sb/Br)
SNAGCU
Level-1-260C-UNLIM
DJ
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a
continuation of the previous line and the two combined represent the entire Top-Side Marking for that device.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
PACKAGE MATERIALS INFORMATION
www.ti.com
8-May-2013
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
LM2773TL/NOPB
DSBGA
YZR
9
250
178.0
8.4
LM2773TLX/NOPB
DSBGA
YZR
9
3000
178.0
8.4
Pack Materials-Page 1
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
1.57
1.57
0.76
4.0
8.0
Q1
1.57
1.57
0.76
4.0
8.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
8-May-2013
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LM2773TL/NOPB
DSBGA
YZR
LM2773TLX/NOPB
DSBGA
YZR
9
250
210.0
185.0
35.0
9
3000
210.0
185.0
35.0
Pack Materials-Page 2
MECHANICAL DATA
YZR0009xxx
D
0.600±0.075
E
TLA09XXX (Rev C)
D: Max = 1.502 mm, Min =1.441 mm
E: Max = 1.502 mm, Min =1.441 mm
4215046/A
NOTES:
A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994.
B. This drawing is subject to change without notice.
www.ti.com
12/12
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2013, Texas Instruments Incorporated
Similar pages