Texas Instruments TPS62840-1YBGEVM56 User manual

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TPS62840-1YBGEVM56 User's Guide
User's Guide
SLUUC17–May 2019
TPS62840-1YBGEVM56 User's Guide
The TPS62840-1YBGEVM56 (BSR056-001) facilitates the evaluation of the TPS6284xYBG family of 750-
mA, step-down converters with 60-nA IQin tiny 1.47-mm by 0.97-mm WCSP packages with 0.4-mm pitch.
The EVM contains 2 separate circuits to create output voltages between 0.8 V and 3.3 V from higher input
voltages between 1.8 V and 6.5 V. All circuits have a maximum height of 1 mm. Due to its extremely low
IQ, the TPS6284x provides a long battery lifetime for systems which have very low current consumption
states such as wearables, Internet of Things- (IoT-) connected devices, and other portable end equipment.
Contents
1 Introduction ................................................................................................................... 2
2 Setup .......................................................................................................................... 4
3 TPS62840-1YBGEVM56 Test Results.................................................................................... 5
4 Board Layout ................................................................................................................. 6
5 Schematic and Bill of Materials (BOM).................................................................................. 12
List of Figures
1 Loop Response Measurement Modification.............................................................................. 3
2 TPS62840 Thermal Performance (VIN = 3.6 V, VOUT = 1.8 V, IOUT = 750 mA)........................................ 5
3 Loop Response (VIN = 3.6 V, VOUT = 1.8 V, IOUT = 750 mA)............................................................. 5
4 Top Assembly................................................................................................................ 6
5 Top Layer..................................................................................................................... 7
6 Internal Layer 1 .............................................................................................................. 8
7 Internal Layer 2 .............................................................................................................. 9
8 Bottom Layer................................................................................................................ 10
9 TPS62840-1YBGEVM56 Angled View .................................................................................. 11
10 TPS62840-1YBGEVM56 Overhead View............................................................................... 11
11 TPS62840 Schematic...................................................................................................... 12
12 TPS62841 Schematic...................................................................................................... 12
List of Tables
1 BSR056 Circuit Options..................................................................................................... 2
2 Performance Specification Summary ..................................................................................... 2
3 TPS62840 Bill of Materials................................................................................................ 13
4 TPS62841 Bill of Materials................................................................................................ 13
Trademarks
All trademarks are the property of their respective owners.

Introduction www.ti.com
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1 Introduction
The TPS6284x is a family of synchronous, step-down converters in a 1.47-mm × 0.97-mm wafer chip-
scale package (WCSP) with 0.4-mm pitch. The BSR056 EVM contains 2 completely independent circuits,
each for a different IC version. See Table 1 for a summary of the BSR056 EVMs.
The reference designator order is grouped together by sub-circuit. Reference designators beginning with
'1' (for example, R1x, J1x, C1x) are part of one sub-circuit. The second digit of each reference designator
is the same for the same component in different sub-circuits. R11 and R21, for example, refer to the same
resistor in each sub-circuit.
Table 1. BSR056 Circuit Options
EVM Version IC Installed Output Voltage Output Voltage Range Output Current
TPS62840-1YBGEVM56
(BSR056-001) TPS62840 (U11) 1.8 V 1.8 - 3.3 V (selectable) 750 mA
TPS62841 (U21) 1.2 V 0.8 - 1.55 V (selectable) 750 mA
1.1 Performance Specification
Table 2 provides a summary of the TPS62840-1YBGEVM56 performance specifications.
Table 2. Performance Specification Summary
SPECIFICATION MIN TYP MAX UNIT
Input voltage 1.8 3.6 6.5 V
Output voltage See Table 1 V
Output current 0 See Table 1 mA
1.2 Modifications
The printed-circuit board (PCB) for this EVM uses the adjustable output voltage versions of this integrated
circuit (IC). Additional input and output capacitors can also be added. Finally, the loop response of the IC
can be measured.
1.2.1 Adjusting the Output Voltage
The output voltage is adjusted though the choice of Rx1 and Rx3 resistors. Since Rx1 and Rx3 are in
parallel, only Rx1 or Rx3 should be installed at the same time. Rx1 is an 0201 size to represent a typical
final solution. However, such a small size is difficult to manually replace. Therefore, Rx3 is provided in an
0603 size to easily change the output voltage. Simply remove Rx1 and install Rx3 in the desired value.
1.2.2 Input and Output Capacitors
Cx4 is provided for an additional input capacitor. This capacitor is not required for proper operation but
can be used to reduce the input voltage ripple.
Cx5, Cx6, and Cx7 are provided for additional output capacitors. These capacitors are not required for
proper operation but can be used to reduce the output voltage ripple and to improve the load transient
response. The total output capacitance must remain within the recommended range in the data sheet for
proper operation.

Cut trace
as shown
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1.2.3 Loop Response Measurement
The loop response of the EVM can be measured with two simple changes to the circuitry. First, cut the
trace between the VOS pin and the output capacitor on the top layer. This change is shown in Figure 1.
Second, install a 10-Ωresistor across the resistor pads on the back of the PCB at Rx2. The pads are
spaced to allow installation of an 0603-sized resistor. With these changes, an ac signal (10-mV, peak-to-
peak amplitude recommended) can be injected into the control loop across the added resistor. Details of
measuring the control loop of DCS-Control devices are found in How to Measure the Control Loop of
DCS-Control™ Devices. The results of this test are shown in Figure 3.
Figure 1. Loop Response Measurement Modification

Setup www.ti.com
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2 Setup
This section describes how to properly use the TPS62840-1YBGEVM56.
2.1 Input/Output Connector Descriptions
Jx1, Pin 1 and 2 – VIN Positive input connection from the input supply for the EVM.
Jx1, Pin 3 and 4 – S+/S- Input voltage sense connections. Measure the input voltage at this point.
Jx1, Pin 5 and 6 – GND Input return connection from the input supply for the EVM.
Jx2, Pin 1 and 2 – VOUT Output voltage connection.
Jx2, Pin 3 and 4 – S+/S- Output voltage sense connections. Measure the output voltage at this point.
Jx2, Pin 5 and 6 – GND Output return connection.
JPx1 – EN EN pin input jumper. Place the supplied jumper across ON and EN to turn
on the IC. Place the jumper across OFF and EN to turn off the IC.
2.2 Setup
To operate the EVM, set jumper JPx1 to the desired position per Section 2.1. Connect the input supply to
Jx1 and connect the load to Jx2.

Frequency (Hz)
Gain (dB)
Phase (deg)
100 200 5001000 10000 100000 1000000
-60 -180
-50 -150
-40 -120
-30 -90
-20 -60
-10 -30
0 0
10 30
20 60
30 90
40 120
50 150
60 180
D001
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3 TPS62840-1YBGEVM56 Test Results
The TPS62840-1YBGEVM56 was used to take all the data in the 1.8V-6.5V, 750mA, 60nA IQStep-Down
Converter data sheet. See the device data sheet for the performance of this EVM. The only difference is
the inductor used. This EVM was designed for the smallest solution size and uses a 0805-size inductor.
The data sheet inductor achieves higher efficiency but is a 0806 size and taller.
Figure 2 shows the thermal performance of the EVM.
Figure 2. TPS62840 Thermal Performance (VIN = 3.6 V, VOUT = 1.8 V, IOUT = 750 mA)
Figure 3. Loop Response (VIN = 3.6 V, VOUT = 1.8 V, IOUT = 750 mA)

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4 Board Layout
This section provides the TPS62840-1YBGEVM56 board layout and illustrations in Figure 4 through
Figure 8. The Gerbers are available on the EVM product page: TPS62840-1YBGEVM56.
Figure 4. Top Assembly

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Figure 5. Top Layer

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Figure 6. Internal Layer 1

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Figure 7. Internal Layer 2

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Figure 8. Bottom Layer