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FEATURES DESCRIPTION
APPLICATIONS
VOUT2
SW1
FB1
SW2
ADJ2
DEF_1
OUT2
CIN
10 μF
VIN2.5V 6V VIN
EN_1
EN_2
MODE/
DATA
TPS62410
GND
Upto800mA
R21
360kΩ
R22
180kΩ
=1.8V
L2
2.2 μH
C =22 µF
Cff2
33pF
upto800mA
R11
270kΩ
R12
180kΩ
VOUT1 =1.5V
L1
2.2 μH
COUT1 =22 µF
V =5V
IN
V =3.6V
IN
PowerSaveMode
MODE/DATA =0
ForcedPWMMode
MODE/DATA =1
0
10
20
30
40
50
60
70
80
90
100
Efficiency-%
0.01 0.1 1 10 100 1000
I -mA
OUT
V =3.3V
OUT
V =3.6V
IN
V =5V
IN
TPS62410
SLVS737 FEBRUARY 2007
2.25MHz 2x800mA Dual Step Down Converter In Small 3x3mm QFN Package
High Efficiency—up to 95%
The TPS62410 device is a synchronous dualstep-down DC-DC converter optimized for batteryV
IN
Range From 2.5 V to 6 V
powered portable applications. It provides two2.25 MHz Fixed Frequency Operation
independent output voltage rails powered by 1-cellOutput Current 2 x 800mA
Li-Ion or 3-cell NiMH/NiCD batteries. The device isAdjustable Output Voltage From 0.6 V to V
IN
also suitable to operate from a standard 3.3V or 5Vvoltage rail.EasyScale™ Optional One Pin Serial Interfacefor Dynamic Output Voltage Adjustment
With an input voltage range of 2.5V to 6V, theTPS62410 is ideal to power portable applications likePower Save Mode at Light Load Currents
smart phones, PDAs, and other portable equipment.180 °Out of Phase Operation
With the EasyScale™ serial interface the outputOutput Voltage Accuracy in PWM Mode ±1%
voltages can be modified during operation. ItTypical 32 µA Quiescent Current for both
therefore supports Dynamic Voltage Scaling for lowConverters
power DSP and processors.100% Duty Cycle for Lowest Dropout
The TPS62410 operates at 2.25MHz fixed switchingAvailable in a 10-Pin QFN (3 ×3mm)
frequency and enter the Power Save Mode operationat light load currents to maintain high efficiency overthe entire load current range. For low noiseapplications the devices can be forced into fixedCell Phones, Smart-phones
frequency PWM mode by pulling the MODE/DATAPDAs, Pocket PCs
pin high. In the shutdown mode, the currentOMAP™ and Low Power DSP Supply
consumption is reduced to 1.2 µA. The device allowsPortable Media Players
the use of small inductors and capacitors to achieveDigital Radio
a small solution size.Digital Cameras
The TPS62410 is available in a 10-pin leadlesspackage (3 ×3mm QFN)
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.EasyScale, OMAP, PowerPAD are trademarks of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Copyright © 2007, 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
DISSIPATION RATINGS
RECOMMENDED OPERATING CONDITIONS
TPS62410
SLVS737 FEBRUARY 2007
ORDERING INFORMATION
(1)
T
A
PART DEFAULT OUTPUT OUTPUT QFN (1) ORDERING PACKAGENUMBER VOLTAGE (2) CURRENT PACKAGE MARKING(1)
OUT1 800mA–40 °C to 85 °C TPS62410 Adjustable DRC TPS62410DRC CATOUT2 800mA
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TIWeb site at www.ti.com .
over operating free-air temperature range (unless otherwise noted)
(1)
VALUE UNIT
Input voltage range on V
IN
(2)
–0.3 to 7 VVoltage range on EN, MODE/DATA, DEF_1 –0.3 to V
IN
+0.3, 7 VMaximum Current into MODE/DATA 500 µAVoltage on SW1, SW2 –0.3 to 7 VVoltage on ADJ2, FB1 –0.3 to V
IN
+0.3, 7 VESD rating
(3)
HBM Human body nodel 2 kVCharge device model 1 kVMachine model 200 VT
J(max)
Maximum junction temperature 150 °CT
A
Operating ambient temperature range –40 to 85 °CT
stg
Storage temperature range –65 to 150 °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.(3) The human body model is a 100pF capacitor discharged through a 1.5k resistor into each pin. The machine model is a 200pFcapacitor discharged directly into each pin.
PACKAGE R
θJA
POWER RATING FOR T
A
25 °C DERATING FACTOR ABOVE T
A
= 25 °C
DRC 49 °C/W 2050mW 21mW/ °C
over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VIN Supply voltage 2.5 6 VOutput voltage range for adjustable voltage 0.6 VIN VT
A
Operating ambient temperature -40 85 °CT
J
Operating junction temperature -40 125 °C
2
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ELECTRICAL CHARACTERISTICS
TPS62410
SLVS737 FEBRUARY 2007
V
IN
= 3.6V, V
OUT
= 1.8V, EN = V
IN
, MODE = GND, L = 2.2 µH, C
OUT
= 20 µF, T
A
= –40 °C to 85 °C typical values are at T
A
=25 °C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY CURRENT
V
IN
Input voltage range 2.5 6.0 VOne converter, I
OUT
= 0mA. PFM mode enabled 19 29 µA(Mode = 0) device not switching,EN1 = 1 OR EN2 = 1Two converter, I
OUT
= 0mA. PFM mode enabled 32 48 µA(Mode = 0) device not switching,I
Q
Operating quiescent current
EN1 = 1 AND EN2 = 1I
OUT
= 0mA, MODE/DATA = GND, for one 23 µAconverter, V
OUT
1.575V
(1)
I
OUT
= 0mA, MODE/DATA = V
IN
, for one 3.6 mAconverter, V
OUT
1.575V
(1)
EN1, EN2 = GND, V
IN
= 3.6V
(2)
1.2 3I
SD
Shutdown current µAEN1, EN2 = GND, V
IN
ramped from 0V to 3.6V
(3)
0.1 1Falling 1.5 2.35V
UVLO
Undervoltage lockout threshold VRising 2.4
ENABLE EN1, EN2
V
IH
High-level input voltage, EN1, EN2 1.2 V
IN
VV
IL
Low-level input voltage, EN1, EN2 0 0.4 VI
IN
Input bias current, EN1, EN2 EN1, EN2 = GND or VIN 0.05 1.0 µA
DEF_1 INPUT
I
IN
Input biasd current DEF_1 DEF_1 = GND or VIN 0.01 1.0 µA
MODE/DATA
V
IH
High-level input voltage, 1.2 V
IN
VMODE/DATAV
IL
Low-level input voltage, 0 0.4 VMODE/DATAI
IN
Input bias current, MODE/DATA MODE/DATA = GND or VIN 0.01 1.0 µAV
OH
Acknowledge output voltage high Open drain, via external pullup resistor V
IN
VV
OL
Acknowledge output voltage low Open drain, sink current 500 µA 0 0.4 V
INTERFACE TIMING
t
Start
Start time 2 µst
H_LB
High time low bit, logic 0 detection Signal level on MODE/DATA pin is > 1.2V 2 200 µst
L_LB
Low time low bit, logic 0 detection Signal level on MODE/DATA pin < 0.4V 2x 400 µst
H_LB
t
L_HB
Low time high bit, logic 1 detection Signal level on MODE/DATA pin < 0.4V 2 200 µst
H_LB
High time high bit, logic 1 detection Signal level on MODE/DATA pin is > 1.2V 2x 400 µst
L_HS
T
EOS
End of Stream T
EOS
2µst
ACKN
Duration of acknowledge condition V
IN
2.5V to 6V 400 520 µs(MODE/DATE line pulled low by thedevice)t
valACK
Acknowledge valid time 2 µst
timeout
Timeout for entering power save MODE/DATA Pin changes from high to low 520 µsmode
(1) Device is switching with no load on the output, L = 3.3 µH, value includes losses of the coil(2) These values are valid after the device has been already enabled one time (EN1 or EN2 = high) and supply voltage V
IN
has notpowered down.(3) These values are valid when the device is disabled (EN1 and EN2 low) and supply voltage V
IN
is powered up. The values remain validuntil the device has been enabled first time (EN1 or EN2 = high). After first enable, Note 3 becomes valid.
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TPS62410
SLVS737 FEBRUARY 2007
ELECTRICAL CHARACTERISTICS (continued)V
IN
= 3.6V, V
OUT
= 1.8V, EN = V
IN
, MODE = GND, L = 2.2 µH, C
OUT
= 20 µF, T
A
= –40 °C to 85 °C typical values are at T
A
=25 °C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
POWER SWITCH
R
DS(ON)
P-Channel MOSFET On-resistance, V
IN
= V
GS
= 3.6V 280 620 m Converter 1,2I
LK_PMOS
P-Channel leakage current V
DS
= 6.0V 1 µAR
DS(ON)
N-Channel MOSFET On-resistance V
IN
= V
GS
= 3.6V 200 450 m Converter 1,2I
LK_SW1/SW2
Leakage Current into SW1/SW2 Pin Includes N-Chanel leakage currnet, 6 7.5 µAV
IN
= open, V
SW
= 6.0V, EN = GND
(4)
I
LIMF
Forward Current OUT 1/2 800mA 2.5V V
IN
6.0V 1.0 1.2 1.38 ALimit PMOS andNMOST
SD
Thermal shutdown Increasing junction temperature 150 °CThermal shudown hysteresis Decreasing junction temperature 20 °C
OSCILLATOR
fSW Oscillator frequency 2.5V VIN 6.0V 2.0 2.25 2.5 MHz
OUTPUT
V
OUT
Adjustable output votage range 0.6 V
IN
VV
ref
Reference voltage 600 mVVoltage positioning active, MODE/DATA = GND,
1.01xV
OUT (PFM)
device operating in PFM mode, VIN = 2.5V to –1.5% 2.5%V
OUT5.0V
(6) (7)DC output voltage accuracy PFMmode, adjustable and fixed output MODE/DATA = GND; device operating in PWM
–1% 0% 1%voltage
(5)
Mode VIN = 2.5V to 6.0V
(7)
V
OUT
V
IN
= 2.5V to 6.0V, Mode/Data = V
IN
, Fixed PWM
–1% 0% 1%operation, 0mA < I
OUT
< I
OUTMAX
(8)
DC output voltage load regulation PWM operation mode 0.5 %/At
Start up
Start-up time Activation time to start switching
(9)
170 µst
Ramp
V
OUT
Ramp UP time Time to ramp from 5% to 95% of V
OUT
750 µs
(4) At pins SW1 and SW2 an internal resistor of 1M is connected to GND(5) Output voltage specification does not include tolerance of external voltage programming resistors(6) Configuration L typ 2.2 µH, C
OUT
typ 20 µF, see parameter measurement information, the output voltage ripple depends on the effectivecapacitance of the output capacitor, larger output capacitors lead to tighter output voltage tolerance(7) In Power Save Mode, PWM operation is typically entered at I
PSM
= V
IN
/32 .(8) For V
OUT
> 2.2V, V
IN
min = V
OUT
+0.3V(9) This time is valid if one converter turns from shutdown mode (EN2 = 0) to active mode (EN2 =1) AND the other converter is alreadyenabled (e.g., EN1 = 1). In case both converters are turned from shutdown mode (EN1 and EN2 = low) to active mode (EN1 and/orEN2=1) a value of typ 80 µs for ramp up of internal circuits needs to be added. After t
Start
the converter starts switching and rampsV
OUT
.
4
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DEVICE INFORMATION
PIN ASSIGNMENTS
DEF_1
FB1
MODE/DATA
VIN
EN1
SW2
ADJ2
GND
EN2
PowerPAD
SW1
1
2
3
4
5
10
9
8
7
6
TopviewDRCpackage
TPS62410
SLVS737 FEBRUARY 2007
TERMINAL FUNCTIONS
TERMINAL
I/O DESCRIPTIONNO.NAME
(QFN)
ADJ2 1 I Input to adjust output voltage of converter 2. In adjustable version (TPS62410) connect a externalresistor divider between VOUT2, this pin and GND to set output voltage between 0.6V and VIN. IfEasyScale™ Interface is used for converter 2, this pin must be directly connected to the output.MODE/DATA 2 I This Pin has 2 functions:1. Operation Mode selection: With low level, Power Save Mode is enabled where the deviceoperates in PFM mode at light loads and enters automatically PWM mode at heavy loads.Pulling this PIN to high forces the device to operate in PWM mode over the whole load range.2. EasyScale™ Interface function: One wire serial interface to change the output voltage of bothconverters. The pin has an open drain output to provide an acknowledge condition if requested.The current into the open drain output stage may not exceed 500 µA. The interface is active ifeither EN1 or EN2 is high.VIN 3 I Supply voltage, connect to VBAT, 2.5V to 6VFB1 4 I Direct feedback voltage sense input of converter 1, connect directly to Vout 1. An internal feed forwardcapacitor is connected between this pin and the error amplifier. In case of fixed output voltage versionsor when the Interface is used, this pin is connected to an internal resistor divider network.DEF_1 5 I/O This pin defines the output voltage of converter 1. The pin acts in TPS62410 as an analog input foroutput voltage setting via external resistors. In fixed default output voltage versions this pin is a digitalinput to select between two fixed default output voltages.In TPS62410 an external resistor network needs to be connected to this pin to adjust the default outputvoltage.SW1 6 Switch Pin of Converter1. Connected to Inductor 1EN1 7 I Enable Input for Converter1, active highGND 8 I GND for both converters, this pin should be connected with the PowerPADEN2 9 I/O Enable Input for Converter 2, active highSW2 10 Switch Pin of Converter 2. Connected to Inductor 2PowerPAD™ Connect to GND
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FUNCTIONAL BLOCK DIAGRAM
Internal
compensated
Error Amp.
Sawtooth
Generator
Skip Comp.Low
PWM
Comp.
Average
CurrentDetector
Skip ModeEntry
VREF Control
Stage
GateDriver
PMOSCurrent
LimitComparator
NMOSCurrent
LimitComparator
LoadComparator
VREF-1%
FB
VOUT1
FB_VOUT
Undervoltage
Lockout
Thermal
Shutdown Softstart
VIN
GND
MODE
Error Amp.
Sawtooth
Generator
PWM
Comp.
VREF Control
Stage
GateDriver
PMOSCurrent
LimitComparator
NMOSCurrent
LimitComparator
LoadComparator
FB_VOUT2
Thermal
Shutdown
Softstart
VIN
GND
MODE
CLK180°
Easy Scale
Interface
CLK0°
CLK180°
2.25MHz
Oscillator
Converter1
Converter2
SW1
SW2
ADJ2
FB1
DEF1
Mode/
DATA
EN1
EN2
VIN
GND
Ext. res. network
Reference
Average
CurrentDetector
Skip ModeEntry
ACK
MOSFET
Opendrain
Internal
compensated
Skip Comp.
VREF+1%
FB_VOUT
Skip Comp.Low
VREF-1%
FB_VOUT
Skip Comp.
VREF+1%
FB_VOUT
Note A
RI3
RI1
RI..N
Int.Resistor
Network
Cff 25pF
Register
DEF1_High
DEF1_Low
RI1
RI..N
Int.Resistor
Network
Cff 25pF
Register
DEF2
NoteB
TPS62410
SLVS737 FEBRUARY 2007
A. In fixed output voltage version, the PIN DEF_1 is connected to an internal digital input and disconnected from theerror amplifierB. To set the output voltage of Converter 2 via EasyScale Interface, ADJ2 pin must be directly connected to VOUT2
6
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PARAMETER MEASUREMENT INFORMATION
SW1
FB1
SW2
ADJ2
DEF_1
VIN
EN_1
EN_2
MODE/
DATA
TPS62410
GND
R11
R12
L1
VIN2.5V-6V
C
10 F
IN
m
2.2 H
LPS4018
m
VOUT1
C 2x10 F
GRM21BR61A106K
OUT1 m
R21
R22
L2
VOUT2
C 2x10 F
GRM21BR61A106K
OUT2 m
C
33pF
ff2
2.2 H
LPS4018
m
TYPICAL CHARACTERISTICS
TABLE OF GRAPHS
TPS62410
SLVS737 FEBRUARY 2007
FIGURE NO.
Efficiency V
OUT1
= 1.2V 1Efficiency V
OUT1
= 1.5V 2Efficiency V
OUT2
= 1.8V 3Efficiency V
OUT2
= 3.3V 4Efficiency vs V
IN
5, 6DC Output Accuracy V
OUT1
= 1.5V 7DC Output Accuracy V
OUT2
= 3.3V 8F
OSC
vs V
IN
9I
q
for one converter 10I
q
for both converters, not switching 11R
DSON
PMOS vs V
IN
12R
DSON
NMOS vs V
IN
13Light Load Output Voltage Ripple in Power Save Mode 14Output Voltage Ripple in Forced PWM Mode 15Output Voltage Ripple in PWM Mode 16Forced PWM/ PFM ModeTransition 17Load Transient Response PFM/PWM 18Load Transient Response PWM Operation 19Line Rransient Response 20Startup Timing One Converter 21Typical Operation V
IN
= 3.6V, V
OUT1
= 1.575V, VOUT2 = 1.8V 22Typical Operation V
IN
= 3.6V, V
OUT1
= 1.8V, V
OUT2
= 3.0V 23Typical Operation V
IN
= 3.6V, V
OUT1
= 1.2V, V
OUT2
= 1.2V 24Dynamic Voltage Positioning 25
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0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
I -mA
OUT
Efficiency-%
V =1.2V
OUT
MODE/DATA =Low
V =5V
V =3.7V
V =3.3V
V =2.7V
IN
IN
IN
IN
MODE/DATA =High
V =5V
V =3.7V
V =3.3V
V =2.7V
IN
IN
IN
IN
0
10
20
30
40
50
60
70
80
90
100
Efficiency-%
0.01 0.1 1 10 100 1000
I -mA
OUT
V =1.8V
OUT
V =2.7V
IN
V =5V
IN
V =3.6V
IN
V =2.7V
IN
V =5V
IN
V =3.6V
IN
PowerSaveMode
MODE/DATA =0
ForcedPWMMode
MODE/DATA =1
V =5V
IN
V =3.6V
IN
PowerSaveMode
MODE/DATA =0
ForcedPWMMode
MODE/DATA =1
0
10
20
30
40
50
60
70
80
90
100
Efficiency-%
0.01 0.1 1 10 100 1000
I -mA
OUT
V =3.3V
OUT
V =3.6V
IN
V =5V
IN
TPS62410
SLVS737 FEBRUARY 2007
TYPICAL CHARACTERISTICS (continued)
FIGURE NO.
Soft Start 26EasyScale Protocol Overview 27EasyScale Protocol Without Acknowledge 28EasyScale Protocol Including Acknowledge 29EasyScale Bit Coding 30MODE/DATA PIN: Mode Selection 31MODE/DATA Pin: Power Save Mode / Interface Communication 32Typical Application Circuit 1.5V / 2.85V Adjustable Outputs 33,34Layout Diagram 35PCB Layout 36
EFFICIENCY V
OUT
= 1.2V EFFICIENCY V
OUT
= 1.5V
Figure 1. Figure 2.
EFFICIENCY V
OUT2
= 1.8V EFFICIENCY V
OUT2
= 3.3V
Figure 3. Figure 4.
8
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50
55
60
65
70
75
80
85
90
95
100
23 4 5 6
Efficiency
MODE/DATA =0
V =1.575V
OUT I =10mA
OUT
I =1mA
OUT
I =200mA
OUT
V -V
IN
50
60
70
80
90
100
3 4 5 6
V -V
IN
Efficiency
MODE/DATA =0
V =3.3V
OUT
I =100mA
OUT
I =10mA
OUT
I =1mA
OUT
1.425
1.450
1.475
1.500
1.525
1.550
1.575
VDC-V
OUT
MODE/DATA =low,PFMMode,VoltagePositioning Active
MODE/DATA = high, forced PWM Mode
V =1.5V
OUT
0.01 0.1 1 10 100 1000
I -mA
OUT
V =2.7V
IN
V =5V
IN
V =3.7V
IN
V =5V
IN
V =3.7V
IN
V =3.3V
IN
V =2.7V
IN
V =3.3V
IN
3.200
3.250
3.300
3.350
3.400
V DC-V
OUT
0.01 0.1 1 10 100 1000
I -mA
OUT
MODE/DATA =low,PFMMode,VoltagePositioning Active
MODE/DATA = high, forced PWM Mode
V =5V
IN
V =5V
IN
V =3.3V
OUT
V 3.7V
IN =
V 4.2V
IN =
PWMMode
Operation
V =3.7V
IN V =4.2V
IN
TPS62410
SLVS737 FEBRUARY 2007
EFFICIENCY vs V
IN
, V
OUT
= 1.575V EFFICIENCY vs V
IN
, V
OUT
= 3.3V
Figure 5. Figure 6.
DC OUTPUT ACCURACY V
OUT1
= 1.5V DC OUTPUT ACCURACY V
OUT2
= 3.3V
Figure 7. Figure 8.
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2
2.05
2.1
2.15
2.2
2.25
2.3
2.35
2.4
2.45
2.5
2.5 3 3.5 4 4.5 5 5.5 6
V -V
IN
Fosc-MHz
-40 C°
85 C°
25 C°
17
18
19
20
21
22
23
24
2.5 3 3.5 4 4.5 5 5.5 6
V -V
IN
Iddq- Am
-40°C
85°C
25°C
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
2.5 3 3.5 4 4.5 5 5.5 6
V -V
IN
RDSon- W
85°C
25°C
-40°C
28
30
32
34
36
38
40
42
2.5 3 3.5 4 4.5 5 5.5 6
V -V
IN
Iddq- Am
85°C
25°C
-40°C
TPS62410
SLVS737 FEBRUARY 2007
F
OSC
vs V
IN
I
q
FOR ONE CONVERTER, NOT SWITCHING
Figure 9. Figure 10.
I
q
FOR BOTH CONVERTERS, NOT SWITCHING R
DSON
PMOS vs V
IN
Figure 11. Figure 12.
10
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0.05
0.1
0.15
0.2
0.25
0.3
2.5 3 3.5 4 4.5 5 5.5 6
V -V
IN
RDSon- W
85°C
25°C
-40°C
IOUT =10mA
VOUT =1.8V20mV/Div
Inductorcurrent100mA/Div
PowerSaveMode
Mode/Data=low
Timebase-10 s/Divm
IOUT =10mA
VOUT =1.8V20mV/Div
Inductorcurrent100mA/Div
Mode/Data=high,
forcedPWMMODEoperation
Timebase-400ns/Div
TPS62410
SLVS737 FEBRUARY 2007
LIGHT LOAD OUTPUT VOLTAGE RIPPLER
DSON
NMOS vs V
IN
IN POWER SAVE MODE
Figure 13. Figure 14.
OUTPUT VOLTAGE RIPPLE OUTPUT VOLTAGE RIPPLEIN FORCED PWM MODE IN PWM MODE
Figure 15. Figure 16.
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IOUT=60mA
IOUT1=540mA
VOUT =1.575V
50mV/Div
Voltagepositioning inPFM
Modereduces voltage drop
duringloadstep
IOUT 200mA/Div
MODE/DATA =low
PWMModeoperation
Timebase-100 s/Divm
IOUT=60mA
IOUT1=540mA
VOUT =1.575V
50mV/Div
IOUT 200mA/Div
MODE/DATA =high
PWMModeoperation
Timebase-100 s/Divm
VIN1V/Div
VOUT 1.575
IOUT 200mA
VIN3.6Vto4.6V
VOUT 50mV/Div
MODE/DATA =high
Timebase-400 s/Divm
TPS62410
SLVS737 FEBRUARY 2007
FORCED PWM/PFM MODE TRANSITION LOAD TRANSIENT RESPONSE PFM/PWM
Figure 17. Figure 18.
LOAD TRANSIENT RESPONSE PWM OPERATION LINE TRANSIENT RESPONSE
Figure 19. Figure 20.
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SW15V/Div
SW25V/Div
Icoil1 200mA/Div
Icoil2 200mA/Div
VIN 3.6V,
VOUT1:1.575V
VOUT2:1.8V
IOUT1 =IOUT2 =200mA
Timebase-100ns/Div
VIN=3.8V
IOUT1max=400mA
SW11V/Div
EN1/EN25V/Div
VOUT1
500mV/Div
Icoil500mA/Div
Timebase-200 s/Divm
SW15V/Div
SW25V/Div
Icoil1 200mA/Div
Icoil2 200mA/Div
VIN 3.6V,
VOUT1:1.8V
VOUT2:3.0V
IOUT1 =IOUT2 =200mA
Timebase-100ns/Div
SW15V/Div
SW25V/Div
Icoil1 200mA/Div
Icoil2 200mA/Div VIN 3.6V,
VOUT1:1.2V
VOUT2:1.2V
IOUT1 =IOUT2 =200mA
Timebase-100ns/Div
DETAILED DESCRIPTION
OPERATION
TPS62410
SLVS737 FEBRUARY 2007
TYPICAL OPERATION V
IN
= 3.6V,STARTUP TIMING ONE CONVERTER V
OUT1
= 1.575V, V
OUT2
= 1.8V
Figure 21. Figure 22.
TYPICAL OPERATION V
IN
= 3.6V, TYPICAL OPERATION V
IN
= 3.6V,V
OUT1
= 1.8V, V
OUT2
= 3.0V V
OUT1
= 1.2V, V
OUT2
= 1.2V
Figure 23. Figure 24.
V
OUT1
CHANGE WITH EASYSCALE
The TPS62410 includes two synchronous step-down converters. The converters operate with typically 2.25MHzfixed frequency pulse width modulation (PWM) at moderate to heavy load currents. If Power Save Mode isenabled, the converters automatically enter Power Save Mode at light load currents and operate in PFM (Pulse
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Converter 1
Converter 2
POWER SAVE MODE
IOUT_PFM_enter +VINDCDC
32 W
(1)
IOUT_PFM_leave +VINDCDC
24 W
(2)
TPS62410
SLVS737 FEBRUARY 2007
DETAILED DESCRIPTION (continued)Frequency Modulation). During PWM operation the converters use a unique fast response voltage modecontroller scheme with input voltage feed-forward to achieve good line and load regulation allowing the use ofsmall ceramic input and output capacitors. At the beginning of each clock cycle initiated by the clock signal, theP-channel MOSFET switch is turned on and the inductor current ramps up until the comparator trips and thecontrol logic turns off the switch.
Each converter integrates two current limits, one in the P-channel MOSFET and another one in the N-channelMOSFET. When the current in the P-channel MOSFET reaches its current limit, the P-channel MOSFET isturned off and the N-channel MOSFET is turned on. If the current in the N-channel MOSFET is above theN-MOS current limit threshold, the N-channel MOSFET remains on until the current drops below its current limit.The two DC-DC converters operate synchronized to each other. A 180 °phase shift between converter 1 andconverter 2 decreases the input RMS current.
In the adjustable output voltage version TPS62410 the converter 1 output voltage can be set via an externalresistor network on PIN DEF_1, which operates as an analog input. In this case, the output voltage can be set inthe range of 0.6V to VIN V. The FB1 Pin must be directly connected to the converter 1 output voltage VOUT1. Itfeeds back the output voltage directly to the regulation loop.
The output voltage of converter 1 can also be changed by the EasyScale serial Interface. This makes the devicevery flexible for output voltage adjustment. In this case, the device uses an internal resistor network.
In the adjustable output voltage version TPS62410, the converter 2 output voltage is set by an external resistordivider connected to ADJ2 Pin and uses an external feed forward capacitor of 33pF.
It is also possible to change the output voltage of converter 2 via the EasyScale Interface. In this case, the ADJ2Pin must be directly connected to converter 2 output voltage VOUT2. At TPS62410 no external resistor networkmay be connected.
The Power Save Mode is enabled with Mode/Data Pin set to 0 for both converters. If the load current of aconverter decreases, this converter will enter Power Save Mode operation automatically. The transition to PowerSave Mode of a converter is independent from the operating condition of the other converter. During PowerSave Mode the converter operates with reduced switching frequency in PFM mode and with a minimumquiescent current to maintain high efficiency. The converter will position the output voltage in PFM mode totypically 1.01xVOUT. This voltage positioning feature minimizes voltage drops caused by a sudden load step.
In order to optimize the converter efficiency at light load the average inductor current is monitored. The devicechanges from PWM Mode to Power Save Mode, if in PWM mode the inductor current falls below a certainthreshold. The typical output current threshold depends on VIN and can be calculated according to Equation 1for each converter.
Equation 1 : Average output current threshold to enter PFM Mode
Equation 2 : Average output current threshold to leave PFM Mode
In order to keep the output voltage ripple in Power Save Mode low, the output voltage is monitored with a singlethreshold comparator (skip comparator). As the output voltage falls below the skip comparator threshold (skipcomp) of 1.01 x VOUTnominal, the corresponding converter starts switching for a minimum time period oftypically 1 µs and provides current to the load and the output capacitor. Therefore the output voltage increasesand the device maintains switching until the output voltage trips the skip comparator threshold (skip comp)again. At this moment all switching activity is stopped and the quiescent current is reduced to minimum. Theload is supplied by the output capacitor until the output voltage has dropped below the threshold again.
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Dynamic Voltage Positioning
VOUT_NOM
+1%
PWMMode
medium/heavyload
PFMMode
lightload
Smooth
increasedload
PWMMode
medium/heavyload
PFMMode
lightload
Fastloadtransient
PWMMode
medium/heavyload
COMP_LOWthreshold –1%
Soft Start
95%
5%
tRAMP