Texas Instruments TPS60120EVM-174 User manual

TPS60120EVMĆ174
BatteryĆPowered, DualĆOutput Power Supply
EVM For DSP's
September 2000 Power Management Products
User’s Guide
SLVU035

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Copyright 2000, Texas Instruments Incorporated

iii
Read This First
Preface
About This Manual
This user’s guide describes the TPS60120EVM-174 battery-powered, dual-
output evaluation module (SLVP174). The SLVP174 provides a convenient
method for evaluating the performance of a dual-output linear regulator.
How to Use This Manual
- Chapter 1 – Introduction
- Chapter 2 – EVM Test Setup
- Chapter 3 – Test Results
Information About Cautions and Warnings
This book may contain cautions and warnings.
This is an example of a caution statement.
A caution statement describes a situation that could potentially
damage your software or equipment.
This is an example of a warning statement.
A warning statement describes a situation that could potentially
cause harm to you.
The information in a caution or a warning is provided for your protection.
Please read each caution and warning carefully.

Trademarks
iv
Related Documentation From Texas Instruments
- TPS70751 data sheet (literature number SLVS291)
- TPS60120 data sheet (literature number SLVS257B)
- TPS60120EVM-142 user’s guide (literature number SLVU022)
Trademarks
PowerPAD is a trademark of Texas Instruments.

Running Title—Attribute Reference
v
Chapter Title—Attribute Reference
Contents
1 Introduction 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Low Power DC/DC Converter 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 LDO Regulator 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Design Strategy 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Adjustment by Switch and Jumper 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Schematic 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Bill of Materials 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 Board Layout 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 EVM Test Setup 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Test Results 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Test Results 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Running Title—Attribute Reference
vi
Figures
1–1 TPS60120EVM-174 Configuration 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 TPS60120EVM-174 Schematic Diagram 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 Top Layer 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4 Bottom Layer (top view) 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–5 Assembly 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 Test Setup 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 Start-Up Curves (TPS70751) 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–2 Start-Up Curves (TPS70751) Over an Extended Period 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–3 Start-Up Curves (TPS60120 and TPS70751) 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–4 Start-Up Curves (TPS60120 With a 1 mA Load and TPS70751) 3-3. . . . . . . . . . . . . . . . . . . . .
3–5 AC Measurement (TPS60120) 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–6 AC Measurement (TPS70751) 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
1–1 TPS60120EVM-174 Bill of Materials 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction
Introduction
This user’s guide describes the TPS60120EVM-174 battery-powered,
dual-output power supply evaluation module (SLVP174). This power supply
solution is comprised of a TPS60120 low-power dc/dc converter and a
TPS70751 dual LDO regulator with integrated supervisory and power-up
sequencing circuitry. Figure 1-1 shows a block diagram of the EVM. The DSP
is not part of the EVM.
Figure 1–1.TPS60120EVM-174 Configuration
VIN1 VOUT1
VIN2 VOUT2
SEQ
EN RESET
MR PG1
TPS70751
CORE
RESET
I/O
DSP
IN
TPS60120
EN
VBAT
VEXT
Off Board
3.3 VO(3.3 VLDO)
(1.8 VLDO)
Topic Page
1.1 Low-Power DC/DC Converter 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 LDO Regulator 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Design Strategy 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Adjustment by Switch and Jumpers 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Schematic 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Bill of Materials 1–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 Board Layout 1–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Low-Power DC/DC Converter
1-2
Introduction
The EVM allows the user to select either two AA batteries in series or an
external power supply as the input supply for the dc/dc converter. As shown
intheblockdiagraminFigure1–1,theTPS60120convertergeneratesa3.3-V
output voltage and can provide up to 200 mA of output current. The 3.3-V
converter output voltage is the input for both of the regulators on the
TPS70751.Usingitspower-upsequencingcircuitry,theTPS70751powersup
its 1.8-V output before its 3.3-V output. The supervisory circuitry reset signal
is low until both voltages are within a certain threshold of regulation. This
configuration is designed to provide a complete power management solution
for battery powered DSP, ASIC, and other low-power applications where two
independent supply voltages are required.
1.1 Low-Power DC/DC Converter
Low-power dc/dc converters with internal charge pumps use a capacitor
instead of an inductor or transformer for energy storage. The Texas
Instruments TPS60120 is one of these low-power dc/dc converters and
performs as a regulated voltage multiplier. Some of the key features of the
TPS60120 include:
- Up to 200-mA output current from 1.8-V to 3.6-V input voltage range
- Regulated 3.3-V ±4% output
- Only four external capacitors are required
- Up to 90% efficiency
- Only 55-µA quiescent supply current
- 0.055-µA current in shutdown mode
- Low-battery indicator
- Available in thermally enhanced TSSOP package (PowerPAD)
For a complete functional description, refer to the TPS60120 data sheet,
SLVS257, and the Charge Pump application note, SLVA070.
PowerPAD is a trademark of Texas Instruments.

LDO Regulator
1-3
Introduction
1.2 LDO Regulator
LDO regulators use a series pass element, feedback network, including an
error amplifier and voltage reference to provide a regulated output voltage
from a slightly larger and variable input voltage. Specific features of the
TPS707xx family of dual LDO regulators include:
- Fixed and adjustable dual-output voltages optimized for low power DSPs
and processor power supplies
- Logic selectable power-up sequencing
- Output currents of 250 mA (regulator 1) and 125 mA (regulator 2)
- Fast response to line and load transient allows use of small, low cost ca-
pacitors
- Integrated supervisory circuit (SVS) with 120-ms delayed open-drain
RESET
- Lowquiescentcurrent(approximately190µA),andlowdropouttoreduce
power and prolong battery operating life
- Output noise only 65 µVRMS
-
Small PowerPADTSSOP packaging
See the TPS707xx family data sheet (SLVS291) for further explanation.

Design Strategy
1-4
Introduction
1.3 Design Strategy
The demand for smaller electronic devices is driving the need for innovative
battery powered solutions including smaller batteries because smaller
batteriesprovidesmallervoltages.Sincethebatterysupplyvoltagesvaryover
the life of the battery, it is necessary to have a dc/dc converter capable of
providingaregulatedoutputoverawiderangeofinputvoltages.Forexample,
AA alkaline batteries have a rated output voltage of 1.5 V but typically provide
1.2 – 1.5 V over most of their life and finally fall to 0.9 V near the end of their
life. NiHM and NiCd rechargeable batteries have a rated output voltage of
1.2 V but typically provide 1.4 V over most of their life and also fall to 1 V near
the end of their life. With its 1.5x or 2x voltage multiplication modes, the
TPS60120converterisanidealsolutionforefficientlyprovidingaregulated3.3
V from batteries whose end of life voltage falls well below the required 3.3 V.
With a minimum input of 1.8 V, the TPS60120 continues to supply power over
the entire usable life of alkaline, NiCd, and NiMH batteries. The TPS60120
alsoprovidesaninputvoltagemonitoringfeatureandanopendrainoutputpin
which is pulled high when the input voltage falls below a user determined
threshold. In this application, the threshold is resistor-divider selected as 1.8
V, and the open-drain output activates a red LED in the event of a low-battery
condition.
Today’s advanced DSPs and microprocessors are designed with the
processor’s core operating at a lower voltage than the input/output (I/O) cells
that communicate with the peripherals in the external system. Without proper
power-up sequencing, the long term reliability of many DSP systems can be
compromised when one rail is powered and the other rail is left inactive for
extended periods of time. In addition, bus contention, a condition when the
processorandanotherdevicebothattempttocontrolabidirectionalbusduring
power up, can affect I/O hardware reliability without proper power-up
sequencing. To provide proper power-up sequencing of the separate 1.8-V
coreandthe3.3-VI/Ovoltage,theTPS70751dualregulatorwaschosen.With
the sequence pin tied high, regulator 2 of the TPS70751 is enabled first and
provides the regulated 1.8-V core output. When the core output reaches
approximately 95% of its regulated voltage, regulator 1 is enabled and
providesthe3.3-Vcorevoltage.Hadsequencingnotbeenaconcern,a single
LDO regulator could have provided a 1.8-V core output and the TPS60120
dc/dc converter could have provided the 3.3-V I/O output directly. In this
configuration,regulator1oftheTPS70751operatesasaswitchtoensurethat
the I/O voltage powers up after the core voltage. In addition, the output
capacitorsofregulator1providesomefilteringtoreducesomeoftherippleon
thedc/dcconverter’soutput.AlsoincludedinthisimplementationisaSchottky
diodewith cathode connectedto the 1.8-Vcore voltage andanode connected
tothe3.3-VI/Ovoltage.Thediodeprovidesadditionalprotectionforlong-term
reliabilityandagainstbuscontentionissuesbyensuringthattherailsarenever
more than 0.3 V apart during power up.

Adjustment by Switch and Jumpers
1-5
Introduction
Aswithanypowersolution,theoutputvoltagesshouldbemonitoredtoensure
that the electronics are properly notified and shut down if the voltages fall
below a predetermined threshold. The TPS70751 monitors both 3.3-V and
1.8-Voutputsandprovidesanopendrain,activelow,120-msdelayedRESET
output. Therefore, the application on this EVM is designed to provide a
complete power management solution for battery powered DSP, ASIC, and
otherdigitalapplicationswheretwoindependentsupplyvoltagesarerequired.
The TPS60120EVM174 from TI provides a convenient method for evaluating
this dual power supply solution as well as the individual operation of the
TPS60120 dc/dc converter and the TPS70751 dual LDO regulator.
1.4 Adjustment by Switch and Jumpers
The schematic for the EVM is provided in Figure 1-2.
- S1 – Toggleswitch S1 is used to enable or disable the TPS60120.
- S2 – Push button switch S2 is connected to the manual reset input of the
TPS70751.DepressingthebuttonwillcausetheRESEToutputofthedual
regulator to toggle.
- JP1 – Jumper JP1 is used to select the input voltage for the charge pump
as either the external power supply or the battery pack as labeled on the
board.
- TP1 – Test point TP1 can be used to measure the output voltage of the
charge pump.

Schematic
1-6
Introduction
1.5 Schematic
Figure1–2 shows the TPS60120EVM-174 schematic diagram.
Figure 1–2. TPS60120EVM-174 Schematic Diagram
19
GND 18
LBI 17
LBO
2GND
20
GND
16
OUT 15
C2+ 14
IN 13
C2–
8C1– 7IN 6C1+ 5OUT 4FB 3ENABLE 1GND
12
PGND 11 PGND
PwrPad
10 PGND
9PGND
+
–
3VIN1 2VIN1 8GND 9VIN2
10 VIN2
1NC
11
NC
12
VOUT2
13
VOUT2
14
VSENSE2
16
PGD_1
17
VSENSE1
18
VOUT1
19
VOUT1
20
NC
PwrPad
4MR1 5MR2 6EN
7SEQ
15
RESET
R3
TP1
C5
3.3 k C6
C4
D1 Red
Low Battery
Manual Reset
S2
C3
R1
357 k
R2
732 k
C2
C1
BP1
J1
GND
EXT. IN 1
2 JP1 S1
OFF
ON
C7
R4
249 k
C8
C10
J2
C9
D2
2 3 4
1VOUT2
VOUT1 RESET
22 µF0.1 µF
2.2µF
2.2 µF
0.1 µF
22 µF
22 µF 0.1µF
22 µF
0.1 µF
TPS70751PWP
BAT54
GND

Bill of Materials
1-7
Introduction
1.6 Bill of Materials
Table 1–2 lists materials required for the TPS60120EVM-174.
Table 1–1.TPS60120EVM-174 Bill of Materials
Ref Des Qty Part Number Description MFG Size
BP1 1 BH2AA–PC Battery holder, 2 AA cells, PC mount MPD
C2, 6, 9,
10 4 GRM39X7R104K016 Capacitor, ceramic, 0.1 µF, 16 V, X7R muRata 603
C3, 4 2 GMK316F225ZG Capacitor, ceramic, 2.2 µF,
35 V, Y5V+80/–20% Taiyo-Yuden 1206
C1, 5, 7,
84 GRM235Y5V226Z010 Capacitor, ceramic, 22 µF,
10 V, Y5V, +80/–20% muRata 1210
D1 1 CMD28–21SRC/TR8 Diode, LED, red, 20 mA, 11.0 Chicago Mini CMD28
D2 1 BAT54 Diode, Schottky, 200 mA, 30 V Vishay-Liteon SOT23
J1 1 ED1660 Header, 2-pin, 5 mm spacing OST
J2 1 ED1662 Header, 4-pin, 5 mm spacing OST
JP1 1 PTC36SAAN Header, 3-pin, 100 mil spacing,
(36 pin strip) Sullins
R1 1 Std Resistor, chip, 375 kΩ, 1/10 W, 1% 805
R2 1 Std Resistor, chip, 732 kΩ, 1/10 W, 1% 805
R3 1 Std Resistor, chip, 3.3 kΩ, 1/10 W, 5% 805
R4 1 Std Resistor, chip, 250 kΩ, 1/10 W, 1% 805
S1 1 EG1218 Switch, 1P2T, slide, PC mount,
200 mA E_Switch
S2 1 EVQ–PJA04Q Switch, 1P1T, PB momentary, 50 mA Panasonic
U1 1 TPS60120PWP IC, charge pump, regulated
3.3 V, 200 mA TI PWP20
U2 1 TPS70751PWP IC, dual-output LDO regulators
w/sequencing for DSP systems TI PWP20
TP1 1 240-345 Test point, red, 1 mm Farnell

Board Layout
1-8
Introduction
1.7 Board Layout
Figures 1–3 and 1-4 show the board layout for the TPS60120EVM-174.
Figure 1–3.Top Layer
Figure 1–4.Bottom Layer (top view)

Board Layout
1-9
Introduction
Figure 1–5.Assembly

2-1
EVM Test Setup
EVM Test Setup
This chapter provides a recommended test setup. Figure 2–1 shows the test
setup. Follow these steps for initial power up of the SLVP174:
1) Adjust the settings of the jumpers to fit test requirements. If the battery
pack is selected as the input, install two AA alkaline batteries into the
battery pack on the back of the board. If an external supply is selected as
the input, connect another voltage source (e.g. power supply or external
batteries)totheEXTINPUTandGNDinputpinsoftheboard.Theexternal
voltage source should supply no more than 3.6 V, the maximum
recommended input voltage for the TPS60120.
2) If desired, connect an external load to either or both outputs. The load
shouldnotexceed200mAonthe3.3-Vchargepumpoutputifitistheonly
loaded output. The load should not exceed 100 mA on either the 3.3-V or
the 1.8-V output if both devices are loaded. Use of short leads on the
external load will prevent loss of performance due to capacitive loading
and/or inductive effects.
3) Connect measurement devices to the test points and output pins as de-
sired.Foramoreprecisemeasurementofnoiseand/orrippleattheoutput
ofthechargepump,useanac-coupledoscilloscopewitheither adifferen-
tial probe placed directly across the output capacitor (C5), or connect a
regular scope probe with as short of a ground lead as possible across the
output capacitor of the charge pump.
Figure 2–1.Test Setup
External
Load
0–100 mA
+
–
Power Supply
+
–
External
Load
0–100 mA
+
–
EVM Enable
Low Battery Indicator Manual reset
RESET Output
TPS60120EVM 174
SLVP174 2AA Input
Dual Output DSP Power
REV (B) 3.3 V
Reset
1.8 V
GND
2000
Reset
On/OFF
Low Battery
Battery
GND
Ext Input
Chapter 2

2-2
EVM Test Setup

3-1
Test Results
Test Results
This chapter presents laboratory test results for the TPS60120EVM-174.
Topic Page
3.1 Test Results 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

Test Results
3-2
Test Results
3.1 Test Results
Figures 3–1 through 3–6 show the results of various test conditions using the
TPS60120EVM-174.
Figures 3–1 shows the startup curves of the 3.3-V output (CH1) and 1.8-V
output(CH2)oftheEVM.EachatnoloadusingswitchSW1tomanuallytrigger
start up.
Figure 3–1.Start-Up Curves (TPS70751)
Figures 3–2 shows the same measurement as in Figure 3–1 except for a
longer time period. It demonstrates the operation of the TPS70751
supervisory circuit RESET output (CH3).
Figure 3–2.Start-Up Curves (TPS70751) Over an Extended Period

Test Results
3-3
Test Results
Figures 3–3 shows the startup curves of the TPS60120, 3.3-V output( CH1),
and the TPS70751, 3.3-V output (CH1) and 1.8-V output (CH2). Switch SW1
was disconnected and the TPS60120 ENABLE (CH3) pin was enabled using
a pulse generator. Both TPS70751 outputs have 1 mA loads. The TPS60120
outputisdistorteddue totheloadonthechargepumpfrom thechargingofthe
TPS70751 output capacitors and the 1 mA loads.
Figure 3–3.Start-Up Curves (TPS60120 and TPS70751)
Figures 3–4 is the same as Figure 3–3 except that the TPS60120 (CH1) now
has a 1 mA load and the Schottky diode between the TPS70751 has been
removed. This figure shows the startup curves if no Schottky diode is used.
Figure 3–4.Start-Up Curves(TPS60120 With a 1 mA Load and TPS70751)