Texas Instruments TPS6100 EVM Series User manual

 
May 2000 Power Management Products
User’s Guide
SLVU029

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Copyright 2000, Texas Instruments Incorporated

How to Use This Manual
iii
Read This First
Preface

About This Manual
This user’s guide describes the evaluation module (EVM) TPS6100x
EVM-156. The TPS6100x family of devices is a single-cell boost converter with
start-up into full load. The TPS6100x family is intended for systems with a
single or dual-battery cell supply and a required output voltage between1.5 V
and 3.3 V.
The guide contains the EVM schematic with an attached bill of material, which
shows the components used with their manufacturers. The layout and the
component placement of the top and bottom side of the board is shown. The
board is assembled on both sides. The following layout considerations point
out the most important layout issues, which must be followed to avoid oscilla-
tions and instability.
The
Setup of the EVM section describes how to start working with the board.
The next section covers the low-battery feature, which typically works as a bat-
tery supervisor.
How to Use This Manual
This document contains the following chapters:
Chapter 1 – Introduction
Chapter 2 – Schematic and Bill of Material
Chapter 3 – Layout
Chapter 4 – Setup of the EVM

Related Documentation From Texas Instruments
iv
Related Documentation From Texas Instruments
1) TPS6100x Single-Cell Boost Converter With Start-Up Into Full
Load –
data sheet (literature number SLVS279)
2) Understanding Boost Power Stages in Switchmode Power Sup-
plies
(literature number SLVA061)
3) Linear Design Seminar (literature number SLYD016)

Running Title—Attribute Reference
v
Contents

1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Schematic and Bill of Material 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Layout 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Top-Side Layout and Component Placement 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Bottom-Side Layout and Component Placement 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Layout Considerations 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Setup of the EVM 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Setup of the EVM 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Low-Battery Function LBI and LBO 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2–1 Schematic of the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 Topology of a Boost Converter Stage 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–1 Setup of the EVM 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–2 Resistive Divider at LBI 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vi

1-1
Introduction

The Texas Instruments TPS6100x are low-power single-cell boost converters.
The TPS61002, TPS61003, and TPS61006 are fixed voltage versions with
1.8-V, 2.5-V and 3.3-V output voltage. The TPS61000 can be adjusted with an
external voltage divider to an output voltage between 1.5 V and 3.3 V. Each
of these four versions is supported with its own EVM. The EVM with the adjust-
able output voltage version is adjusted to 3.3-V output voltage.
The maximum output current at an input voltage down to 0.8 V (single battery-
cell supply) is 100 mA. If two battery cells are used as supply, output currents
up to 200 mA can be drawn at an input voltage down to 1.6 V. The device can
be started into a full load with supply voltages down to 0.9 V over the full tem-
perature range.
The high power conversion efficiency of up to 90%, a low quiescent current of
less than 50 µA, and a special power-save mode makes this family of devices
well-suited for battery-powered applications. These EVMs should help to eval-
uate the device directly in the application.
The board can be used, for example, to measure the efficiency of different ex-
ternal components and determine the best for the application. The ripple of the
output voltage be can easily measured, depending on the output capacitor
used. The board is assembled with a 22-µF multilayer ceramic output capaci-
tor from Taiyo Yuden, which has an ultralow ESR to keep the output ripple as
low as possible.
If another fixed-voltage version is of interest, the assembled device can be re-
placed with the desired device. Other fixed voltage versions are TPS61001,
TPS61004, and TPS61005 with 1.5-V, 2.8-V and 3-V output voltage. Free
samples can be ordered from http://www.ti.com. Type in the complete device
name in the quick search box and select Check stock or order under Availabil-
ity/Samples .
To get more detailed information about the device, see the TPS6100x data
sheet (literature number SLVS279).
Chapter 1

1-2

2-1
Schematic and Bill of Material
    
Figure 2–1.Schematic of the EVM
EN
COMP
FB
GND
VO
LBO
LBI
NC
SWITCH
VBAT
R6 LP1
R5
C5
C6
R3
R4
OUT
C2
J1 J2
L1
C1 C3
R2 R1
IN
D1
Chapter 2

2-2
Table 2–1.Bill of Material
Component Value Functionality
IC1 Texas Instruments:
TPS6100x
10-pin MSOP package
Controller-IC in the boost-converter stage
L1
10 µH, Coilcraft: DS1608C-103 Inductor for storing energy during on-state of the power transistor
D1
Motorola: MBRM120LT3 Schottky diode for rectifying current flow, works as a free-wheeling diode
R1 1 MΩ, 1% Resistor to adjust the threshold voltage, supervised by the
low-battery function
R2 909 kΩ, 1% Resistor to adjust the threshold voltage, supervised by the
low-battery function
R3 178 kΩ, 1%
(only TPS61000-ADA) Resistor to adjust the output voltage for the adjustable version
R4 1 MΩ, 1%
(only TPS61000-ADA) Resistor to adjust the output voltage at the adjustable version
R5 33 kΩ, 5% Resistor to compensate the control loop
R6 470 kΩ, 5% Pullup resistor for the open-drain output of the low-battery output
C1 10 µF, Taiyo Yuden:
JMK316BJ106ML-T Input capacitor to stabilize input voltage
C2 22 µF, Taiyo Yuden:
LMK432BJ226MM-T Output capacitor to supply the load during on state of the power transistor
C3 100 nF, 10 V Input capacitor for filtering spikes
C5 10 nF, 10 V Capacitor to compensate the control loop
C6 47 pF, 10 V Capacitor to compensate the control loop
J1 3-pin To enable (connect to VBATT) or disable (to GND) the device
J2 3-pin Not used for this family of devices
IN 4-pin To connect the device to the battery and GND →Input
OUT 4-pin To connect the device to the load and GND →Output

3-1
Layout

Topic Page
3.1 Top-Side Layout and Component Placement 3-2. . . . . . . . . . . . . . . . . . . .
3.2 Bottom-Side Layout and Component Placement 3-2. . . . . . . . . . . . . . . . .
3.3 Layout Considerations 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

Top-Side Layout and Component Placement
3-2
3.1 Top-Side Layout and Component Placement
3.2 Bottom-Side Layout and Component Placement

Layout Considerations
3-3
Layout
3.3 Layout Considerations
The basic components of a boost converter topology (as shown in Figure 3–1)
are placed on the top side of the EVM. These are the components which carry
the high currents. The ground plane is divided into two parts that are connected
to the ground pin of the device. The ground plane on the top side carries the
inductor current and the load current back to the ground terminal of the power
supply. The ground plane on the bottom side of the EVM is for connecting the
sensitive parts to ground. These are the compensation network and the volt-
age divider for the low-battery function and for fixing the output voltage on the
adjustable version. It is very important to keep noisy and high current traces
away from sensitive lines or to separate them by using additional ground
traces between them, otherwise instability or oscillation can occur. The resis-
tive divider for fixing the output voltage should be placed as close as possible
to the FB pin.
Since the device has a high switching frequency of 500 kHz and large peak
currents, the layout is an extemely important part of the design. All power com-
ponents like the input and output capacitors, the inductor, the diode, and the
device should be kept as close together as possible. The traces should be kept
short, wide, and direct.
Figure 3–1.Topology of a Boost Converter Stage
_
+
VREF
L1 D1
C2C1
VIVO
IC1

3-4

4-1
Setup of the EVM
   
Topic Page
4.1 Setup of the EVM 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Low-Battery Function LBI and LBO 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 4

4-2
4.1 Setup of the EVM
Figure 4–1.Setup of the EVM
Current Meter
for Input Current
(See Note A)
+
–
Power
Supply
Oscilloscope
for Output Voltage
and Output Ripple
Voltage Meter for
LBO Output Voltage
Voltage Meter
for Input Voltage
Current Meter
for Output Current
Important
LOAD
Note A: Use this current meter only if the sense wires of the supply are used.
Follow these steps for proper operation of the EVM:
1) Connect J1, the Enable-pin, with VDD as shown in Figure 4–1.
2) Connect the sense wires of the power supply to the input terminals of the
board, or solder the connections of the power supply to the terminals.
3) Connect the input voltage meter between the board on the one side and
the power supply and input current meter on the other side.
4) Connect the oscilloscope between the output terminals of the EVM on the
one side and the load and output current meter on the other side.

Low-Battery Function LBI and LBO
4-3
Setup of the EVM
4.2 Low-Battery Function LBI and LBO
The low battery feature is typically used to supervise the battery voltage and
to indicate when the voltage goes below an adjustable threshold voltage. The
threshold voltage can be adjusted by an external resistive divider connected
to the low-battery input (LBI) as shown in Figure 4–2. It can be calculated by
using equation 1.
V
threshold

R
2
R
11
V
REF
909
k 
1 M 10.5
V 0.955 V
(1)
On the EVM, the threshold voltage is adjusted to about 0.96 V. If the battery
voltage goes below 0.96 V, the LBO open-drain output is pulled down to
ground. Otherwise, it is in a high-impedance state and the voltage is pulled up
via the external resistor R6 to VO. R1 is a 1-MΩresistor, so that the current
through R1 is about 50 times higher than the typical current into the LBI pin of
10 nA. Therefore, the LBI input current can be neglected in the calculations.
Figure 4–2.Resistive Divider at LBI
TPS6100x
LBI LBO
R2
909 kΩ
R1
1 MΩ
R6
470 kΩ
VLBO
Note:
Voltage drops can be found on the input line although there are two input ca-
pacitors. These spikes can be the reason for triggering the LBO earlier than
expected, since the input voltage decreases the adjusted threshold voltage
for short periods of time. Be aware of this.

4-4