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FEATURES DESCRIPTION
APPLICATIONS
Typical Application Circuit (600-mA Output Current)
VIN
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C1
R2
R1
C2
C3
10 µF
VI
2.5 V to 6 V L1
10 µH
C4
10 µF
VO
0.7 V to VI / 600 mA
40
45
50
55
60
65
70
75
80
85
90
95
100
0 0.01 0.10 1 100010 100
Efficiency − %
EFFICIENCY
vs
LOAD CURRENT
IL − Load Current − mA
VO = 1.8 V
VI = 3.6 V
Mode = High
Mode = Low
VI = 5 V
VI = 3.6 V
VI = 2.7 V
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
600 mA/1.25 MHz HIGH-EFFICIENCY STEP-DOWN CONVERTER
•Up to 95% Conversion Efficiency
The TPS6202x is a high efficiency synchronousstep-down dc-dc converter optimized for battery pow-•Typical Quiescent Current: 18 µA
ered portable applications. This device is ideal for•Load Current: 600 mA
portable applications powered by a single Li-Ion•Operating Input Voltage Range: 2.5 V to 6.0 V
battery cell or by 3-cell NiMH/NiCd batteries. With an•Switching Frequency: 1.25 MHz output voltage range from 6.0 V down to 0.7 V, thedevice supports low voltage DSPs and processors in•Adjustable and Fixed Output Voltage
PDAs, pocket PCs, as well as notebooks and•Power Save Mode Operation at Light load
subnotebook computers. The TPS6202x operates atCurrents
a fixed switching frequency of 1.25 MHz and entersthe power save mode operation at light load currents•Active-Low MODE pin on TPS62021
to maintain high efficiency over the entire load current•100% Duty Cycle for Lowest Dropout
range. For low noise applications, the device can be•Internal Softstart
forced into fixed frequency PWM mode by pulling the•Dynamic Output Voltage Positioning
MODE pin high. The difference between theTPS6202x and the TPS62021 is the logic level of the•Thermal Shutdown
MODE pin. The TPS62021 has an active-low MODE•Short-Circuit Protection
pin. The TPS6202x supports up to 600-mA load•10 Pin MSOP PowerPad™ Package
current.•10 Pin QFN 3 X 3 mm Package
•PDA, Pocket PC and Smart Phones•USB Powered Modems•CPUs and DSPs•PC Cards and Notebooks•xDSL Applications
•Standard 5-V to 3.3-V Conversion
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstruments semiconductor products and disclaimers thereto appears at the end of this data sheet.PowerPad is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Copyright © 2003–2004, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.
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ABSOLUTE MAXIMUM RATINGS
PACKAGE DISSIPATION RATINGS
RECOMMENDED OPERATING CONDITIONS
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
These devices have limited built-in ESD protection. The leads should be shorted together or the deviceplaced in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.
ORDERING INFORMATION
PACKAGE PACKAGE MARKINGMODE PIN OUTPUTT
A
LOGIC LEVEL VOLTAGE
MSOP
(1)
QFN
(2)
MSOP QFN
MODE Adjustable TPS62020DGQ TPS62020DRC BBK BBJ–40 °C to 85 °C MODE Adjustable TPS62021DGQ TPS62021DRC ASH ASJMODE 3.3 V TPS62026DGQ TPS62026DRC BKI BKJ
(1) The DGQ package is available in tape and reel. Add R suffix (DGQR) to order quantities of 2500 parts per reel.(2) The DRC package is available in tape and reel. Add R suffix (DRCR) to order quantities of 3000 parts per reel.
over operating free-air temperature range unless otherwise noted
(1)
UNITS
Supply voltage VIN
(2)
–0.3 V to 7 VVoltages on EN, MODE, FB, SW
(2)
–0.3 V to V
CC
+0.3 VContinuous power dissipation See Dissipation Rating TableOperating junction temperature range –40 °C to 150 °CStorage temperature range –65 °C to 150 °CLead temperature (soldering, 10 sec) 260 °C
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratingsonly, and functional operation of the device at these or any other conditions beyond those indicated under recommended operatingconditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.(2) All voltage values are with respect to network ground terminal.
T
A
≤25 °C T
A
= 70 °C T
A
= 85 °CPACKAGE R
θJA
(1)
POWER RATING POWER RATING POWER RATING
MSOP 60 °C/W 1.67 W 917 mW 667 mWQFN 48.7 °C/W 2.05 W 1.13 W 821 mW
(1) The thermal resistance, R
θJA
is based on a soldered PowerPAD using thermal vias.
MIN TYP MAX UNIT
V
I
Supply voltage 2.5 6.0 VV
O
Output voltage range for adjustable output voltage version 0.7 V
I
VI
O
Output current 600 mAL Inductor
(1)
3.3 10 µHC
I
Input capacitor
(1)
10 µFC
O
Output capacitor
(1)
10 µFT
A
Operating ambient temperature –40 85 °CT
J
Operating junction temperature –40 125 °C
(1) Refer to application section for further information
2
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ELECTRICAL CHARACTERISTICS
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
V
I
= 3.6 V, V
O
= 1.8 V, I
O
= 600 mA, EN = VIN, T
A
= –40 °C to 85 °C, typical values are at T
A
= 25 °C (unless otherwise noted)
(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY CURRENT
V
I
Input voltage range 2.5 6.0 VI
(Q)
Operating quiescent current I
O
= 0 mA, device is not switching 18 35 µAI
SD
Shutdown supply current EN = GND 0.1 1 µAV
UVLO
Under-voltage lockout threshold 1.5 2.3 V
ENABLE AND MODE
V
EN
EN high level input voltage 1.4 VV
EN
EN low level input voltage 0.4 VI
EN
EN input bias current EN = GND or VIN 0.01 1.0 µAV
(MODE)
MODE high level input voltage 1.4 VV
(MODE)
MODE low level input voltage 0.4 VI
(MODE)
MODE input bias current MODE = GND or VIN 0.01 1.0 µA
POWER SWITCH
P-channel MOSFET on-resistance V
I
= V
GS
= 3.6 V 115 210 m Ωr
DS(ON)
P-channel MOSFET on-resistance V
I
= V
GS
= 2.5 V 145 270 m ΩI
lkg(P)
P-channel leakage current V
DS
= 6.0 V 1 µAN-channel MOSFET on-resistance V
I
= V
GS
= 3.6 V 85 200 m Ωr
DS(ON)
N-channel MOSFET on-resistance V
I
= V
GS
= 2.5 V 115 280 m ΩI
Ikg(N)
N-channel leakage current V
DS
= 6.0 V 1 µAI
L
P-channel current limit 2.5 V < V
I
< 6.0 V 0.9 1.1 1.3 AThermal shutdown 150 °C
OSCILLATOR
V
FB
= 0.5 V 1 1.25 1.5 MHzf
S
Oscillator frequency
V
FB
= 0 V 625 kHz
OUTPUT
Adjustable output TPS62020,V
O
0.7 V
IN
Vvoltage range TPS62021V
ref
Reference voltage 0.5 VTPS62020, V
I
= 2.5 V to 6.0 V; I
O
= 0 mA 0% 3%V
FB
Feedback voltage TPS62021 VV
I
= 2.5 V to 6.0 V; 0 mA ≤I
O
≤600 mA –3% 3%Adjustable
V
I
= 3.6 V to 6.0 V; I
O
= 0 mA 0% 3%V
O
Fixed output voltage TPS62026 3.3 V VV
I
= 3.6 V to 6.0 V; 0 mA ≤I
O
≤600 mA –3% 3%V
I
= V
O
+ 0.5 V (min 2.5 V) to 6.0 V, I
O
= 10Line regulation
(1)
0 %/VmALoad regulation
(1)
I
O
= 10 mA to 600 mA 0 %/mALeakage current into SW pin V
I
> V
O
, 0 V ≤V
SW
≤V
I
0.1 1 µAI
Ikg(SW)
Reverse leakage current into pin SW V
I
= open; EN = GND; V
SW
= 6.0 V 0.1 1 µAf Short circuit switching frequency V
FB
= 0 V 625 kHz
(1) The line and load regulations are digitally controlled to assure an output voltage accuracy of ±3%.
3
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PIN ASSIGNMENTS
1
2
3
4
5
10
9
8
7
6
EN
VIN
VIN
GND
FB
PGND
PGND
SW
SW
MODE
DGQ PACKAGE
(TOP VIEW)
NOTE:The PowerPAD must be connected to GND.
1
2
3
4
5
10
9
8
7
6
EN
VIN
VIN
GND
FB
PGND
PGND
SW
SW
MODE
DRC PACKAGE
(TOP VIEW)
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
Terminal Functions
TERMINAL
I/O DESCRIPTIONNAME NO.
EN 1 I Enable. Pulling EN to ground forces the device into shutdown mode. Pulling EN to V
I
enables the device. ENshould not be left floating and must be terminated.VIN 2, 3 I Supply voltage inputGND 4 Analog groundFB 5 I Feedback. Connect an external resistor divider to this pin.If a fixed-output-voltage device is ued, connect FB directly to the output.MODE 6 I The difference between TPS6202x and TPS62021 is the logic level of the MODE pin. The TPS62021 has anMODE active-low MODE pin. The TPS6202x is forced into fixed-frequency PWM mode by pulling the MODE pin high.Pulling the MODE pin low enables the Power Save Mode, operating in PFM mode (Pulse frequency modulation)at light load current, and in fixed frequency PWM at medimum to heavy load currents. In contrast, the TPS62021is forced into PWM mode by pulling the MODE pin low.SW 7, 8 I/O This is the switch pin of the converter and connected to the drain of the internal power MOSFETsPGND 9, 10 Power ground
4
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(See Note A)
FB PGND
SW
VIN
EN
Undervoltage
Lockout
Bias supply
Control Logic
+
−
LoadComparator
1.25 MHz
Oscillator
Vref = 0.5 V
Driver
Shoot−thru
Logic
P−Channel
Power MOSFET
N−Channel
Power MOSFET
R1
R2
Soft
Start
+
−
+
−
Current limit Comparator
SkipComparator
Gm
Saw Tooth
Generator
V
I
+
−
Vcomp
S
R
+
−
Comp High
Comp Low
Comp Low 2
Comp High
Comp Low
Comp Low 2
−
+
Comparator
Compensation
Ref
Ref
PGND
VIN
GNDMODE
MODE
SW
For the Adjustable Version the FB Pin Is
Directly Connected to the Gm Amplifier
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
FUNCTIONAL BLOCK DIAGRAM
NOTE A: The TPS6202x has an active-high MODE pin. The TPS62021 has an active-low MODE pin.NOTE B: The resistor network R1 and R2 is only integrated in fixed-output devices.
5
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TYPICAL CHARACTERISTICS
40
45
50
55
60
65
70
75
80
85
90
95
100
0 0.01 0.10 1 100010 100
Efficiency − %
IL − Load Current − mA
VO = 3.3 V
VI = 3.6 V
Mode = Low
VI = 5 V
Mode = Low
40
45
50
55
60
65
70
75
80
85
90
95
100
0 0.01 0.10 1 100010 100
Efficiency − %
IL − Load Current − mA
VO = 1.8 V
VI = 3.6 V
Mode = High
Mode = Low
VI = 5 V
VI = 3.6 V
VI = 2.7 V
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
Table of Graphs
FIGURE
ηEfficiency vs Load current 1, 2, 3ηEfficiency vs Input voltage 4I
Q
No load quiescent current vs Input voltage 5, 6f
s
Switching frequency vs Input voltage 7r
DS(on)
P-Channel switch r
DS(on)
vs Input voltage 8r
DS(on)
N-Channel rectifier switch r
DS(on
) vs Input voltage 9Load transient response 10PWM operation 11Power save mode operation 12Start-up 13
EFFICIENCY EFFICIENCYvs vsLOAD CURRENT LOAD CURRENT
Figure 1. Figure 2.
6
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40
45
50
55
60
65
70
75
80
85
90
95
100
0 0.01 0.10 1 100010 100
Efficiency − %
IL − Load Current − mA
VO = 1.5 V
VI = 5 V
VI = 3.6 V
VI = 2.7 V
Mode = Low
Mode = High
70
75
80
85
90
95
100
2.5 3 3.5 4 4.5 5 5.5 6
IL = 250 mA
IL = 1 mA
VO = 1.8 V
Mode = Low
Efficiency − %
VI − Input Voltage − V
IL = 500 mA
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
2.5 3 3.5 4 4.5 5 5.5 6
Quisecent Current −
VI − Input Voltage − V
mA
MODE = High
TA = 25°C
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
EFFICIENCY EFFICIENCYvs vsLOAD CURRENT INPUT VOLTAGE
Figure 3. Figure 4.
QUIESCENT CURRENT QUIESCENT CURRENTvs vsINPUT VOLTAGE INPUT VOLTAGE
Figure 5. Figure 6.
7
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1.18
1.18
1.19
1.19
1.20
1.20
1.21
1.21
1.22
1.22
1.23
1.23
2.5 2.9 3.3 3.7 4.1 4.5 4.9 5.3 5.7 6
f − Switching Frequency − MHz
VI − Input Voltage − V
TA = 85°C
TA = 25°C
TA = −40°C
2.5 2.9 3.3 3.7 4.1 4.5 4.9 5.3 5.7 6
VI − Input Voltage − V
TA = 85°C
TA = 25°C
TA = −40°C
0.080
0.090
0.100
0.110
0.120
0.130
0.140
0.150
0.160
0.170
0.180
ΩDS(on) −
P−Channel r
VI = 3.6 V,
VO = 1.8 V,
PWM/PFM Operation
50 µs/div
100 mV/div
VO
50 mA to 600 mA
IO
2.5 2.9 3.3 3.7 4.1 4.5 4.9 5.3 5.7 6
VI − Input Voltage − V
TA = 85°C
TA = 25°C
TA = −40°C
N-Channel Rectifier r Ω
0.050
0.060
0.070
0.080
0.090
0.100
0.110
0.120
0.130
0.140
0.150
DS(on) −
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
SWITCHING FREQUENCY P-CHANNEL r
DS(on)vs vsINPUT VOLTAGE INPUT VOLTAGE
Figure 7. Figure 8.
N-CHANNEL RECTIFIER r
DS(on)vsINPUT VOLTAGE LOAD TRANSIENT RESPONSE
Figure 9. Figure 10.
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VI = 3.6 V,
VO = 1.8 V
500 ns/div
2 V/div
VSW
20 mV/div
VO
500 mA/div
IL
VI = 3.6 V,
VO = 1.8 V
2.5 µs/div
5 V/div
VSW
20 mV/div
VO
500 mA/div
IL
VI = 3.6 V,
VO = 1.8 V,
IO = 545 mA
200 µs/div
2 V/div
Enable
1 V/div
VO
200 mV/div
II
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
PWM OPERATION POWER SAVE MODE OPERATION
Figure 11. Figure 12.
START-UP
Figure 13.
9
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DETAILED DESCRIPTION
OPERATION
POWER SAVE MODE OPERATION
Itransition
VI
18.66
(1)
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
The TPS6202x is a synchronous step-down converter that typically operates at a 1.25-MHz fixed frequency. Atmoderate to heavy load currents the device operates in pulse-width modulation (PWM), and at light load currentsthe device enters power-save mode operation using pulse-requency modulation (PFM). When operating in PWMmode, the typical switching frequency is 1.25 MHz with a minimum switching frequency of 1 MHz. This makesthe device suitable for xDSL applications, minimizing RF (radio frequency) interference.
During PWM operation the converter uses a unique fast response voltage mode controller scheme with inputvoltage feed-forward to achieve good line and load regulation allowing the use of small ceramic input and outputcapacitors. At the beginning of each clock cycle initiated by the clock signal (S) the P-channel MOSFET switchturns on and the inductor current ramps up until the comparator trips and the control logic turns off the switch.The current limit comparator also turns off the switch in case the current limit of the P-channel switch isexceeded. After the dead time preventing current shoot through, the N-channel MOSFET rectifier is turned onand the inductor current ramps down. The next cycle is initiated by the clock signal, again turning off theN-channel rectifier and turning on the P-channel switch.
The Gm amplifier as well as the input voltage determines the rise time of the saw tooth generator, and therefore,any change in input voltage or output voltage directly controls the duty cycle of the converter, giving a very goodline and load transient regulation.
As the load current decreases, the converter enters power save mode operation. During power save mode theconverter operates with reduced switching frequency in PFM mode and with a minimum quiescent currentmaintaining high efficiency.
The converter monitors the average inductor current and the device enters power save mode when the averageinductor current is below the threshold. The transition point between PWM and power save mode is given by thetransition current with the following equation:
During power save mode the output voltage is monitored with the comparator by the threshold's comp low andcomp high. As the output voltage falls below the comp low threshold set to typically 0.8% above the nominaloutput voltage, the P-channel switch turns on. The P-channel switch remains on until the transition currentEquation 1 is reached. Then the N-channel switch turns on completing the first cycle. The converter continues toswitch with its normal duty cycle determined by the input and output voltage but with half the nominal switchingfrequency of 625-kHz typ. Thus the output voltage rises and, as soon as the output voltage reaches the comphigh threshold of 1.6%, the converter stops switching. Depending on the load current, the converter switches fora longer or shorter period of time in order to deliver the energy to the output. If the load current increases and theoutput voltage can not be maintained with the transition current Equation 1 , the converter enters PWM again.See Figure 11 and Figure 12 under the typical graphs section and Figure 14 for power save mode operation.Among other techniques this advanced power save mode method allows high efficiency over the entire loadcurrent range and a small output ripple of typically 1% of the nominal output voltage.
Setting the power save mode thresholds to typically 0.8% and 1.6% above the nominal output voltage at lightload current results in a dynamic voltage positioning achieving lower absolute voltage drops during heavy loadtransient changes. This allows the converter to operate with small output capacitors like 10 µF or 22 µF and stillhaving a low absolute voltage drop during heavy load transient. Refer to Figure 14 as well for detailed operationof the power save mode.
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1.6%
0.8%
VO
Comp High
Comp Low
Comp Low 2
PWM Mode at Medium to Full Load
PFM Mode at Light Load
DYNAMIC VOLTAGE POSITIONING
MODE (AUTOMATIC PWM/PFM OPERATION AND FORCED PWM OPERATION)
100% DUTY CYCLE LOW DROPOUT OPERATION
VImin VOmaxIOmaxrDS(on)maxRL
(2)
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
DETAILED DESCRIPTION (continued)
Figure 14. Power Save Mode Thresholds and Dynamic Voltage Positioning
The converter enters the fixed frequency PWM mode as soon as the output voltage falls below the comp low 2threshold.
As described in the power save mode operation sections before and as detailed in Figure 14 the output voltageis typically 0.8% (i.e., 1% on average) above the nominal output voltage at light load currents, as the device is inpower save mode. This gives additional headroom for the voltage drop during a load transient from light load tofull load. In the other direction during a load transient from full load to light load the voltage overshoot is alsominimized by turning on the N-Channel rectifier switch to pull the output voltage actively down.
Connecting the MODE pin of the TPS6202x to GND enables the automatic PWM and power save modeoperation. The converter operates in fixed frequency PWM mode at moderate to heavy loads and in the PFMmode during light loads, maintaining high efficiency over a wide load current range.
Pulling the TPS6202x MODE pin high forces the converter to operate constantly in the PWM mode even at lightload currents. The advantage is the converter operates with a fixed switching frequency that allows simplefiltering of the switching frequency for noise sensitive applications. In this mode, the efficiency is lower comparedto the power save mode during light loads (see Figure 1 to Figure 3 ). For additional flexibility it is possible toswitch from power save mode to forced PWM mode during operation. This allows efficient power managementby adjusting the operation of the TPS6202x to the specific system requirements.
The difference between the TPS6202x and the TPS62021 is the logic level of the MODE pin. The TPS62021 hasan active-low MODE pin. Pulling the TPS62021 MODE pin high enables the automatic PWM and Power SaveMode.
The TPS6202x offers a low input to output voltage difference while still maintaining regulation with the use of the100% duty cycle mode. In this mode, the P-Channel switch is constantly turned on. This is particularly useful inbattery powered applications to achieve longest operation time by taking full advantage of the whole batteryvoltage range. i.e. The minimum input voltage to maintain regulation depends on the load current and outputvoltage and can be calculated as:
with:
•I
O(max)
= maximum output current plus inductor ripple current•r
DS(on)
max = maximum P-channel switch t
DS(on)
.
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SOFTSTART
SHORT-CIRCUIT PROTECTION
THERMAL SHUTDOWN
ENABLE
UNDERVOLTAGE LOCKOUT
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
DETAILED DESCRIPTION (continued)•R
L
= DC resistance of the inductor•V
O
max = nominal output voltage plus maximum output voltage tolerance
The TPS6202x series has an internal softstart circuit that limits the inrush current during start-up. This preventspossible voltage drops of the input voltage in case a battery or a high impedance power source is connected tothe input of the TPS6202x.
The softstart is implemented with a digital circuit increasing the switch current in steps of typically I
LIM
/8, I
LIM
/4,I
LIM
/2 and then the typical switch current limit of 1.1 A as specified in the electrical parameter table. The start-uptime mainly depends on the output capacitor and load current, see Figure 13 .
As soon as the output voltage falls below 50% of the nominal output voltage, the converter switching frequencyas well as the current limit is reduced to 50% of the nominal value. Since the short-circuit protection is enabledduring start up the device does not deliver more than half of its nominal current limit until the output voltageexceeds 50% of the nominal output voltage. This needs to be considered in case a load acting as a current sinkis connected to the output of the converter.
As soon as the junction temperature of typically 150 °C is exceeded the device goes into thermal shutdown. Inthis mode, the P-Channel switch and N-Channel rectifier are turned off. The device continues its operation whenthe junction temperature falls below typically 150 °C again.
Pulling the EN low forces the part into shutdown mode, with a shutdown current of typically 0.1 µA. In this mode,the P-Channel switch and N-Channel rectifier are turned off and the whole device is in shut down. If an outputvoltage is present during shut down, which could be an external voltage source or super cap, the reverseleakage current is specified under electrical parameter table. For proper operation the enable (EN) pin must beterminated and should not be left floating.
Pulling EN high starts up the device with the softstart as described under the section Softstart.
The undervoltage lockout circuit prevents device misoperation at low input voltages. It prevents the converterfrom turning on the switch or rectifier MOSFET with undefined conditions.
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APPLICATION INFORMATION
ADJUSTABLE OUTPUT VOLTAGE VERSION
VO0.5 V 1R1
R2
(3)
C1 1
210 kHz R1
(4)
C2 R1
R2 C1
(5)
VIN
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C3
22 µF
VI
2.5 V to 6 V L1
6.2 µH
C4
22 µF
VO
1.8 V / 600 mA
R1
470 kΩ
R2
180 kΩ
C1
33 pF
C2
100 pF
Inductor Selection
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
When the adjustable output voltage version TPS6202x is used, the output voltage is set by the external resistordivider. See Figure 15 .
The output voltage is calculated as:
with R1 + R2 ≤1 M Ωand internal reference voltage V
ref
typical = 0.5 V
R1 + R2 should not be greater than 1 M Ωbecause of stability reasons. To keep the operating quiescent currentto a minimum, the feedback resistor divider should have high impedance with R1+R2 ≤1 M Ω. Due to this and thelow reference voltage of V
ref
= 0.5 V, the noise on the feedback pin (FB) needs to be minimized. Using acapacitive divider C1 and C2 across the feedback resistors minimizes the noise at the feedback, withoutdegrading the line or load transient performance.
C1 and C2 should be selected as:
with:
•R1 = upper resistor of voltage divider•C1 = upper capacitor of voltage divider
For C1 a value should be chosen that comes closest to the calculated result.
with:
•R2 = lower resistor of voltage divider•C2 = lower capacitor of voltage divider
For C2, the selected capacitor value should always be selected larger than the calculated result. For example, inFigure 15 for C2 100 pF are selected for a calculated result of C2 = 88.42 pF.
If quiescent current is not a key design parameter C1 and C2 can be omitted, and a low impedance feedbackdivider has to be used with R1 + R2 < 100 k Ω. This reduces the noise available on the feedback pin (FB) as wellbut increases the overall quiescent current during operation. The higher the programmed output voltage thelower the feedback impedance has to be for best operation when not using C1 and C2.
Figure 15. Adjustable Output Voltage Version
The TPS6202x uses typically a 10-µH output inductor. Larger or smaller inductor values can be used to optimizethe performance of the device for specific operation conditions. When changing inductor values, the product ofthe inductor value times output-capacitor value (L ×C) should stay constant. For example, when reducing the
13
www.ti.com
ILVO
1–VO
VI
Lƒ
(6)
ILmax IOmax
IL
2
(7)
Output Capacitor Selection
IRMSCout VO
1–VO
VI
Lƒ1
23
(8)
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
APPLICATION INFORMATION (continued)inductor value, increase the output capacitor accordingly. See the application circuits in Figure 17 , Figure 18 , andFigure 19 . The selected inductor has to be rated for its dc resistance and saturation current. The dc resistance ofthe inductance directly influences the efficiency of the converter. Therefore an inductor with the lowest dcresistance should be selected for highest efficiency. Formula Equation 7 calculates the maximum inductor currentunder static load conditions. The saturation current of the inductor should be rated higher than the maximuminductor current as calculated with formula Equation 7 . This is needed because during heavy load transient theinductor current rises above the value calculated under Equation 7 .
with:
•7 = Switching frequency (1.25 MHz typical)•L = Inductor value• ∆ I
L
= Peak-to-peak inductor ripple current•I
L
max = Maximum inductor current
The highest inductor current occurs at maximum V
I
.
Open core inductors have a soft saturation characteristic and they can usually handle higher inductor currentsversus a comparable shielded inductor. A more conservative approach is to select the inductor current rating forthe maximum switch current of 1.3 A for the TPS6202x. Keep in mind that core material differs from inductor toinductor, and this impacts efficiency, especially at high switching frequencies. Refer to Table 1 and the typicalapplications and inductors selection.
Table 1. Inductor Selection
INDUCTOR VALUE DIMENSIONS COMPONENT SUPPLIER
10 µH 6,6 mm ×4,75 mm ×2,92 mm Coilcraft DO1608C-10310 µH 5,0 mm ×5,0 mm ×3,0 mm Sumida CDRH4D28-1003.3 µH 5,0 mm ×5,0 mm ×2,4 mm Sumida CDRH4D22 3R36.8 µH 5,8 mm ×7,4 mm ×1,5 mm Sumida CMD5D13 6R8
The advanced, fast-response voltage-mode control scheme of the TPS6202x allows the use of small ceramiccapacitors with a typical value of 10 µF and 22 µF without having large output voltage under and overshootsduring heavy load transients. Ceramic capacitors having low ESR values have the lowest output voltage rippleand are recommended. If required, tantalum capacitors may be used as well. Refer to Table 2 for componentselection. If ceramic output capacitors are used, the capacitor RMS ripple current rating always meets theapplication requirements. Just for completeness the RMS ripple current is calculated as:
At nominal load current the device operates in PWM mode and the overall output voltage ripple is the sum of thevoltage spike caused by the output capacitor ESR plus the voltage ripple caused by charging and discharging theoutput capacitor:
14
www.ti.com
VOVO
1–VO
VI
Lƒ1
8COƒESR
(9)
Input Capacitor Selection
Layout Considerations
VIN
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C3
22 µF
VIL1
6.2 µH
C2
22 µF
VO
The Switch Node Must Be
Kept as Small as Possible
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
Where the highest output voltage ripple occurs at the highest input voltage, V
I
.
At light load currents, the device operates in power save mode and the output voltage ripple is independent ofthe output capacitor value. The output voltage ripple is set by the internal comparator thresholds. The typicaloutput voltage ripple is 1% of the nominal output voltage.
Because of the nature of the buck converter having a pulsating input current, a low ESR input capacitor isrequired for best input voltage filtering and minimizing the interference with other circuits caused by high inputvoltage spikes. The input capacitor should have a minimum value of 10 µF for the TPS6202x. The input capacitorcan be increased without any limit for better input voltage filtering.
Table 2. Input and Output Capacitor Selection
CAPACITOR
CASE SIZE COMPONENT SUPPLIER COMMENTSVALUE
Taiyo Yuden JMK212BJ106MG Ceramic10 µF 0805
TDK C12012X5ROJ106K CeramicTaiyo Yuden JMK316BJ106KL10 µF 1206 CeramicTDK C3216X5ROJ106M22 µF 1206 Taiyo Yuden JMK316BJ226ML Ceramic22 µF 1210 Taiyo Yuden JMK325BJ226MM Ceramic
For all switching power supplies, the layout is an important step in the design especially at high peak currentsand switching frequencies. If the layout is not carefully done, the regulator might show stability problems as wellas EMI problems. Therefore, use wide and short traces for the main current paths as indicated in bold inFigure 16 . These traces should be routed first. The input capacitor should be placed as close as possible to theIC pins as well as the inductor and output capacitor. The feedback resistor network should be routed away fromthe inductor and switch node to minimize noise and magnetic interference. To further minimize noise fromcoupling into the feedback network and feedback pin, the ground plane or ground traces should be used forshielding. A common ground plane or a star ground as shown below should be used. This becomes veryimportant especially at high switching frequencies of 1.25 MHz.
Figure 16. Layout Diagram
15
www.ti.com
THERMAL INFORMATION
TYPICAL APPLICATIONS
Vout
3.3V/0.6A
Vin
3.6V to 6.0V VIN
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C3
10uF C1
22pF
L1
3.3uH
C4
22uF
R2
110k
R1
620k
C2
150pF
C5
22uF
Vout
1.8V/0.6A
Vin
2.5V to 6.0V
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C3
10uF C1
22pF
L1
6.8uH
C4
22uF
R2
240k
R1
620k
C2
68pF
VIN
Vout
1.2V/0.6A
Vin
2.5V to 6.0V
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62020
C3
10uF C1
33pF
L1
10uH
C4
10uF
R2
330k
R1
470k
C2
68pF
VIN
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
One of the most influential components on the thermal performance of a package is board design. In order totake full advantage of the heat dissipating abilities of the PowerPAD™ packages, a board should be used thatacts similar to a heat sink and allows for the use of the exposed (and solderable), deep downset pad. For furtherinformation please refer to Texas Instruments application note (SLMA002 )PowerPAD Thermally EnhancedPackage.
The PowerPAD™ of the 10-pin MSOP package has an area of 1,52 mm ×1,79 mm ( ±0,05 mm) and must besoldered to the PCB to lower the thermal resistance. Thermal vias to the next layer further reduce the thermalresistance.
Figure 17. Li-Ion to 3.3 V With Improved Load Transient Response
Figure 18. 1.8 V Output Using 6.8 µH Inductor
Figure 19. 1.2 V Output Using 10 µH Inductor
16
www.ti.com
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
49
10
5
7
8
6
TPS62026
VIN
Vin
3.6 V to 6 V Vout
3.3 V/0.6 A
L1
6.8 H
C2
22 F
C1
10 F
VIN
EN
MODE
SW
FB
PGND
PGND
SW
GND
2
3
1
4 9
10
5
7
8
6
TPS62026
VIN
Vin
3.6 V to 6 V Vout
3.3 V / 0.6 A
L1
10 H
C2
10 F
C1
10 F
TPS62020
TPS62021
TPS62026
SLVS076C – JUNE 2003 – REVISED DECEMBER 2004
Figure 20. TPS62026 Fixed 3.3 V Output Using 6.8 µH inductor
Figure 21. TPS62026 Fixed 3.3 V Output Using 10 µH inductor
17
PACKAGE OPTION ADDENDUM
www.ti.com 17-Aug-2012
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
TPS62020DGQ ACTIVE MSOP-
PowerPAD DGQ 10 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62020DGQG4 ACTIVE MSOP-
PowerPAD DGQ 10 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62020DGQR ACTIVE MSOP-
PowerPAD DGQ 10 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62020DGQRG4 ACTIVE MSOP-
PowerPAD DGQ 10 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62020DRCR ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TPS62020DRCRG4 ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TPS62021DGQ PREVIEW MSOP-
PowerPAD DGQ 10 TBD Call TI Call TI
TPS62021DGQR ACTIVE MSOP-
PowerPAD DGQ 10 TBD Call TI Call TI
TPS62021DGQRG4 ACTIVE MSOP-
PowerPAD DGQ 10 TBD Call TI Call TI
TPS62021DRCR ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TPS62021DRCRG4 ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TPS62026DGQ ACTIVE MSOP-
PowerPAD DGQ 10 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62026DGQG4 ACTIVE MSOP-
PowerPAD DGQ 10 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62026DGQR ACTIVE MSOP-
PowerPAD DGQ 10 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62026DGQRG4 ACTIVE MSOP-
PowerPAD DGQ 10 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-1-260C-UNLIM
TPS62026DRCR ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TPS62026DRCRG4 ACTIVE SON DRC 10 3000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
PACKAGE OPTION ADDENDUM
www.ti.com 17-Aug-2012
Addendum-Page 2
(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.
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.
TAPE AND REEL INFORMATION
*All dimensions are nominal
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
TPS62020DGQR MSOP-
Power
PAD
DGQ 10 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
TPS62020DRCR SON DRC 10 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2
TPS62021DRCR SON DRC 10 3000 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q2
TPS62021DRCR SON DRC 10 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2
TPS62026DGQR MSOP-
Power
PAD
DGQ 10 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
TPS62026DRCR SON DRC 10 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2
PACKAGE MATERIALS INFORMATION
www.ti.com 17-Aug-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
TPS62020DGQR MSOP-PowerPAD DGQ 10 2500 364.0 364.0 27.0
TPS62020DRCR SON DRC 10 3000 367.0 367.0 35.0
TPS62021DRCR SON DRC 10 3000 370.0 355.0 55.0
TPS62021DRCR SON DRC 10 3000 367.0 367.0 35.0
TPS62026DGQR MSOP-PowerPAD DGQ 10 2500 364.0 364.0 27.0
TPS62026DRCR SON DRC 10 3000 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 17-Aug-2012
Pack Materials-Page 2
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