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TPS62770
SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
TPS62770 Multi-Rail DC/DC Converter For Wearable Applications
1 Features
3 Description
•
•
The TPS62770 is a tiny power solution for wearable
applications including a 370nA ultra low Iq step-down
converter, a slew rate controlled load switch and a
dual mode step-up converter. The output voltage of
the step-down converter can be selected with three
VSEL pins between 1.0 V, 1.05 V, 1.1 V, 1.2 V, 1.8
V, 1.9 V, 2.0 V and 3.0 V. The output voltage can be
changed during operation. In shutdown mode, the
output of the step-down converter is pulled to GND.
The integrated load switch is internally connected to
the output of the step-down converter and features
slew rate control during turn on phase. Once turned
off, its output is connected to GND.
1
•
•
•
VIN Range 2.5 V to 5.5 V
370 nA Iq Step-Down Converter
– 8 Selectable Output Voltages (1.0V to 3.0V)
– 300 mA Output Current
– Output Discharge Function
Slew Rate Controlled Load Switch with Discharge
Function
Dual Mode Step-Up Converter
– Load Disconnect
– Constant Output Voltage Adjustable up to 15 V
(VFB 0.8 V) / 12 V Fixed
– LED Current Driver with PWM to Current
Conversion (max VFB Voltage 200 mV @ D =
100%)
Tiny 16pin 1.58 x 1.58mm WCSP Package 0.4mm
pitch
2 Applications
•
•
•
Wearable and Personal Electronics
Fitness Accessories
Health Monitoring and Medical Accessories
The dual mode step-up converter can generate a
constant output voltage up to 15 V, such as PMOLED
supply; or, a constant output current, such as LED
back light supply. The output voltage can be adjusted
up to 15 V with external resistors, or set to fixed 12 V
by connecting the FB pin to VIN. The device features
an internal over voltage protection of 17.7 V in case
the FB node is left open or tight to GND. It includes
an internal rectifier and load disconnect function.
When used as constant output current driver, the
device offers a PWM to analog converter to scale
down the reference voltage according to the duty
cycle of the PWM signal.
The device is available in a small 16pin 0.4mm pitch
WCSP package.
Device Information(1)
PART NUMBER
TPS62770
PACKAGE
DSBGA (16)
BODY SIZE (NOM)
1.58mm x 1.58mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Schematic
TPS62770
VIN
CIN
10mF
EN1
DC/DC 1
Step Down Converter
SW1
VO1
VSEL3
VSEL2
L1 = 2.2mH
VOUT1 = 1.8V/300mA
MCU / BLE
COUT1
10mF
VSEL1
Load Output = 1.8V
ON/OFF
CTRL
Load Switch
LOAD
Sensors
L2 = 10mH
VOUT2 = 12V / 30mA
SW2
EN2/PWM
FB
DC/DC 2
Step up converter
VO2
PMOLED
COUT2
10mF
BM
GND1
GND2
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
TPS62770
SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
5
5
5
8
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information .................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram ......................................... 9
7.3 Feature Description................................................. 10
7.4 Device Functional Modes........................................ 13
8
Application and Implementation ........................ 17
8.1 Application Information............................................ 17
8.2 Typical Applications ............................................... 18
9 Power Supply Recommendations...................... 32
10 Layout................................................................... 32
10.1 Layout Guidelines ................................................. 32
10.2 Layout Example .................................................... 33
11 Device and Documentation Support ................. 34
11.1
11.2
11.3
11.4
11.5
Device Support ....................................................
Documentation Support .......................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
34
34
34
34
34
12 Mechanical, Packaging, and Orderable
Information ........................................................... 34
4 Revision History
Changes from Revision A (March 2016) to Revision B
•
Changed Application and Implementation section organization for clarity. .......................................................................... 17
Changes from Original (February 2016) to Revision A
•
2
Page
Page
Changed device status to Production Data and released the full data sheet. ....................................................................... 1
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SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
5 Pin Configuration and Functions
YFP Package
16-Pin DSBGA
Top View
1
2
3
4
A
GND2
SW2
VO2
VSEL3
B
BM
VSEL2
EN2/
PWM
FB
C
SW1
EN1
VSEL1
CTRL
D
VIN
GND1
VO1
LOAD
Table 1. Pin Functions
PIN
I/O
DESCRIPTION
NAME
NO
EN2/PWM
B3
IN
GND2
A1
PWR
SW2
A2
IN
VO2
A3
OUT
BM
B1
IN
This pin controls the operation mode of the step-up converter. With BM = high, the device features a low
feedback voltage of 200mV, which can be scaled down by the integrated PWM to analog converter. With
BM = low, the device operates with a 0.8V feedback voltage and operates as a step-up converter with
voltage regulation. This pin must be terminated and set before the device is enabled.
FB
B4
IN
Feedback pin for the step-up converter to set the output voltage / current. Connect the pin to the center tap
of a resistor divider to program the output voltage. When it is connected to the VIN pin, the output voltage
is set to 12 V by an internal feedback divider network. When used as a LED current driver connect the
sense resistor between this pin and GND. The LED string is connected between FB pin and VO2.
EN1
C2
IN
Enable pin for the step-down converter. High level enables the devices, low level turns the device into
shutdown mode. The pin must be terminated.
VSEL1
C3
IN
VSEL2
B2
IN
Output voltage selection pins. See Table 2 for VOUT selection. These pins must be terminated. The pins
can be dynamically changed during operation.
VSEL3
A4
IN
CTRL
C4
IN
VIN
D1
PWR
VIN power supply pin. Connect the input capacitor close to this pin for best noise and voltage spike
suppression. A ceramic capacitor of 10μF is required.
GND1
D2
PWR
GND supply pin for the step-down converter. Connect this pin close to both, the GND terminal of the input
and output capacitor.
SW1
C1
OUT
This is the switch pin of the step-down converter and is connected to the internal MOSFET switches.
Connect the inductor L1 between this terminal and the output capacitor.
VO1
D3
OUT
Output of the step-down converter. The output voltage is sensed via this pin to the internal feedback divider
network for the regulation loop. In addition the internal load switch is connected between VO1 pin and
LOAD pin. Connect this pin directly to the output capacitor with a short trace. The pin is connected to
GND1 and discharges the output capacitor when the converter is disabled.
LOAD
D4
OUT
Output terminal of the internal load switch. With CTRL = high, the internal load switch connects VO1 to the
LOAD pin. The switch features a slew rate control. This pin is pulled to GND with the CTRL = low. If not
used, leave the pin open.
Enable pin for the step-up converter. High level enables the devices, low level turns the device into
shutdown mode. A PWM signal can be applied to this pin when used as a constant current driver (BM pin
connected to VIN). The pin must be terminated.
GND supply pin for the step-up converter. Connect this pin close to the GND terminals of the input and
output capacitors.
The switch pin of the step-up converter. It is connected to the drain of the internal power MOSFET.
Connect the inductor L2 between this pin and the input capacitor CIN
Output of the step-up converter.
This pin controls the load switch between VO1 and LOAD. With CTRL = low, the LOAD switch is disabled.
The pin must be terminated.
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TPS62770
SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
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Table 2. Output Voltage Setting Step-Down Converter
VO1 [V]
VSEL3
VSEL2
VSEL1
1.0
0
0
0
1.05
0
0
1
1.1
0
1
0
1.2
0
1
1
1.8
1
0
0
1.9
1
0
1
2.0
1
1
0
3.0
1
1
1
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
MAX
UNIT
VIN, FB
–0.3
6
V
SW1
–0.3
VIN +0.3V
V
EN1, EN2/PWM, CTRL, BM, VSEL1-3
–0.3
VIN +0.3V
V
SW2, VO2
-0.3
32
V
VO1, LOAD
–0.3
3.7
V
TJ
Operating junction temperature range
–40
125
°C
Tstg
Storage temperature range
–65
150
°C
Pin voltage
(1)
(2)
(2)
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute–maximum–rated conditions for extended periods may affect device reliability.
All voltage values are with respect to network ground terminal GND.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
4
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all
pins (1)
Charged device model (CDM), per JEDEC specification
JESD22-C101, all pins (2)
UNIT
± 2000
V
±500
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. The human body
model is a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
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SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
6.3 Recommended Operating Conditions
MIN NOM MAX
VIN
Input voltage range at VIN pin
IOUT1
DC/DC 1 Step down
converter output current
IOUT2
DC/DC 2 Step up
converter output current
2.5
L1 = 2.2µH, COUT1 = 10 µF
UNIT
5.5
V
300
mA
2.5V < VIN < 5.5V, VOUT2 = 12V, COUT2 = 10uF, L = 10µH
30
2.5V < VIN < 5.5V, VOUT2 = 12V, COUT2 = 2x 10uF, L = 10µH
100
3V < VIN < 5.5V, VOUT2 = 5V, COUT2 = 2x 10uF, L = 4.7µH
200
ILOAD
Load current (current
from LOAD pin)
TJ
Operating junction temperature range
-40
125
TA
Ambient temperature range
-40
85
mA
100
°C
6.4 Thermal Information
TPS62770
THERMAL METRIC
(1)
YFP
UNIT
TERMINALS
RθJA
Junction-to-ambient thermal resistance
RθJCtop
Junction-to-case (top) thermal resistance
0.6
RθJB
Junction-to-board thermal resistance
13.8
ψJT
Junction-to-top characterization parameter
2.8
ψJB
Junction-to-board characterization parameter
13.7
RθJCbot
Junction-to-case (bottom) thermal resistance
n/a
(1)
90.6
°C/W
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
6.5 Electrical Characteristics
VIN = 3.6V, TA = –40°C to 85°C typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
EN1 = EN2/PWM = GND, CTRL GND, BM = GND,
0.1
1850
nA
Rising VIN
2.1
2.22
Falling VIN
1.9
2
SUPPLY
Shutdown current
into VIN
ISD
VTH_ UVLO+
VTH_UVLO-
Undervoltage
lockout threshold
V
INPUTS EN1, EN2/PWM, BM, CTRL,VSEL 1-3
VIH
TH
High level input
threshold
VIL TH
Low level input
threshold
IIN
Input bias Current
1.2
0.4
V
TJ = 25°C
10
TJ = –40°C to 85°C
25
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nA
5
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Electrical Characteristics (continued)
VIN = 3.6V, TA = –40°C to 85°C typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
EN1 = VIN, EN2/PWM = GND, CTRL = GND, IOUT = 0µA, VOUT = 1.8V,
device not switching,
370
1850
EN1 = VIN, EN2/PWM = GND, IOUT = 0mA, CTRL = GND, VOUT =
1.8V , device switching
500
UNIT
STEP-DOWN CONVERTER
Operating
quiescent current
IQ
Output voltage
range
Output voltage
accuracy
VVOUT
RDS(ON)
1.0
PFM mode
PWM mode
DC output voltage
load regulation
VOUT = 1.8V
DC output voltage
line regulation
VOUT = 1.8V, IOUT = 10 mA, 2.5V ≤ VIN ≤ 5.5V
High side
MOSFET onresistance
Low Side
MOSFET onresistance
%
0
2.5
-2
0
2
%/mA
0
%/V
0.45
Ω
IOUT = 50mA
0.22
480
600
720
600
RDSCH_VO1
Discharge switch
on-resistance
EN = GND, IVO1 = -10mA into VO1 pin
IIN_VO1
Bias current into
VO1 pin
EN = VIN, VOUT = 1.8V
VTH_100+
Auto 100% Mode
leave detection
threshold (1)
Rising VIN,100% Mode is left with VIN = VOUT + VTH_100+ , max value at
TJ = 85°C
VTH_100-
Auto 100% Mode
enter detection
threshold (1)
Falling VIN, 100% Mode is entered with VIN = VOUT + VTH_100-, max
value at TJ = 85°C
tONmin
Minimum ON time
VOUT = 2.0V, IOUT = 0 mA
tOFFmin
Minimum OFF time
tStartup_delay
Regulator start up
delay time
tSoftstart
Softstart time with
reduced switch
current limit
ILIM_softstart
V
-2.5
Low side MOSFET
switch current limit
High side
MOSFET switch
current limit
3.0
0.001
High side
MOSFET switch
current limit
ILIMF
nA
20
TJ = 25°C
40
TJ = –40°C to 85°C
mA
65
100
1010
150
250
mA
Ω
nA
370
mV
85
200
225
ns
50
ns
From transition EN1 = low to high until device starts switching
80
310
1
5
ms
700
1200
µs
150
200
Reduced switch current limit during softstart
mA
Low side MOSFET
switch current limit
150
LOAD SWITCH
RLOAD
MOSFET onresistance
ILOAD = 50mA, CTRL = VIN, VOUT = 1.8V,
0.6
1.27
Ω
trise_LOAD
VLOAD rise time
Starting with CTRL low to high transition, time to ramp VLOAD from
95%, VOUT = 1.8V, ILOAD = 20mA
315
800
μs
RDCHRG
MOSFET onresistance
20
65
Ω
(1)
6
VIN is compared to the programmed output voltage (VOUT). When VIN–VOUT falls below VTH_100- the device enters 100% Mode by turning
the high side MOSFET on. The 100% Mode is exited when VIN–VOUT exceeds VTH_100+ and the device starts switching. The hysteresis
for the 100% Mode detection threshold VTH_100+ - VTH_100- will always be positive and will be approximately 50 mV(typ.)
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Electrical Characteristics (continued)
VIN = 3.6V, TA = –40°C to 85°C typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
110
200
µA
15
V
STEP-UP CONVERTER
IQ_VIN
Quiescent current
into VIN pin
EN2/PWM = VIN, BM = GND, EN1 = GND, no load, no switching, VOUT
= 12 V
VOUT
Output voltage
range
EN2/PWM = VIN, BM = GND
VOUT_12V
12-V output
voltage accuracy
FB pin connected to VIN pin, EN2/PWM = VIN, BM = GND
VFB
Feedback voltage
PWM mode, BM = GND, EN2/PWM = VIN
4.5
11.7
12
12.3
V
0.775
0.795
0.814
V
PFM mode, BM = GND, EN2/PWM = VIN
Feedback
regulation voltage
under brightness
control
tDim_Off
tDim_On
0.803
EN2/PWM = VIN, BM = VIN,
V
189
200
206
mV
VFB =50mV, BM = VIN, D(PWM) @ EN2/PWM = 25%,
40
50
60
mV
VFB = 20mV, BM = VIN, D(PWM) @ EN2/PWM = 10%
13
Dimming signal on
pin EN2/PWM
20
27
270
160
17.7
18.4
17
VOVP
Output overvoltage
protection
threshold
VOVP_HYS
Over voltage
protection
hysteresis
IFB_LKG
Leakage current
into FB pin
ISW_LKG
Leakage current
into SW pin
EN2/PWM = GND
RDS(on)
Isolation MOSFET
on resistance
VOUT = 12 V
850
Low-side MOSFET VOUT = 12 V
on resistance
450
800
VOUT = 12 V, PWM mode
850
mV
200
nA
5
500
nA
Switching
frequency
tON_min
Minimal switch on
time
ILIM_SW
Peak switch
current limit
VOUT = 12 V
ILIM_CHG
Pre-charge current
VOUT = 0 V
tSoftstart
Pre-charge time
BM = GND, EN2/PWM from low to high until device starts switching,
IOUT2 = 0mA, COUT2 = 10uF
6
Startup time
VOUT from VIN to 12 V, COUT_effective = 2.2 µF, IOUT = 0 A
6
mΩ
1050
1250
kHz
150
250
ns
970
1230
mA
30
55
mA
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5
fSW
730
μs
μs
1
ms
7
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SLVSCX0B – FEBRUARY 2016 – REVISED APRIL 2016
www.ti.com
6.6 Typical Characteristics
160
1000
900
800
TA = -20°C
TA = 0°C
TA = 25°C
140
TA = 60°C
TA = 85°C
120
100
600
IQ [mA]
IQ [nA]
700
TA = -40°C
500
400
80
60
300
TA = -40°C
TA = -20°C
TA = 0°C
TA = 25°C
TA = 60°C
TA = 85°C
40
200
100
20
0
0
2
3
4
5
2
6
2.5
3
3.5
VIN [V]
4
4.5
5
5.5
6
VIN [V]
EN2/PWM = Low
EN1 = High
VOUT1 Set to 1.8 V
Device not
Switching
EN2/PWM = High
EN1 = Low
Figure 1. Quiescent Current IQStep-Down converter
VOUT2 Set to 12 V
Device not
Switching
Figure 2. Quiescent Current IQStep-Up converter
500
TA = -40°C
TA = -20°C
400
TA = 0°C
TA = 25°C
350
TA = 60°C
TA = 85°C
ISDN [nA]
450
300
250
200
150
100
50
0
2
2.5
3
3.5
4
4.5
5
5.5
VIN [V]
EN1 = EN2/PWM = Low
Figure 3. Shutdown Current ISDN
8
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7 Detailed Description
7.1 Overview
The TPS62770 is a tiny power solution for wearable applications including a 370nA ultra low Iq step-down
converter, a slew rate controlled load switch and a dual mode step-up converter. The output voltage of the stepdown converter can be selected with three VSEL pins between 1.0 V, 1.05 V, 1.1 V, 1.2 V, 1.8 V, 1.9 V, 2.0 V
and 3.0 V.
The dual mode step-up converter can generate a constant output voltage up to 15 V, such as PMOLED supply
or, a constant output current, such as LED back light supply.
7.2 Functional Block Diagram
TPS62770
VIN
D1
B1
EN1
C2
B1
VSEL1
C3
B1
VSEL2
B2
B1
VSEL3
A4
B1
C4
B1
CTRL
DC/DC 1
Step Down
Converter
Load Switch
SW1
VO1
LOAD
VO2
A2
B1
B1
B1
SW2
BM
C1
D3
D4
A3
DC/DC 2
Step up converter
EN2/PWM
B3
B1
FB B4
GND1
D2
GND2
A1
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7.3 Feature Description
7.3.1 Step-Down Converter Device
CTRL
VO1
EN1
Ultra Low Power
Reference VREF = 1.2 V
VSEL1
UVLO
Softstart
VOUT
UVLO
Comp
VSEL2
VFB
VIN
Internal
Feedback
Divider
Network*
VSEL3
UVLO
VTH_UVLO
VIN
VOUT
Load Switch
Auto 100% Mode
Comp
100%
VIN
Mode
CTRL
VTH_100
UVLO Discharge
Slew Rate
Control
EN
Current
Limit Comparator
Timer
DCS
Control
VOUT
Discharge
EN
UVLO
Min. On
Limit
High Side
LOAD
Power Stage
VIN
PMOS
Min. OFF
VOUT
Direct Control
& Compensation
EN
Control
Logic
VFB
Gate Driver
Anti
Shoot-Through
SW1
VREF
Error
Amplifier
Main
Comparator
* Typical 50 MW
Limit
Low Side
NMOS
Current
Limit Comparator
GND1
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Figure 4. Block Diagram Step-Down Converter with Load Switch
7.3.1.1 DCS-Control™
TI's DCS-Control™ (Direct Control with Seamless Transition into Power Save Mode) is an advanced regulation
topology, which combines the advantages of hysteretic and voltage mode control. Characteristics of DCS-Control
™ are excellent AC load regulation and transient response, low output ripple voltage and a seamless transition
between PFM and PWM mode operation. DCS-Control™ includes an AC loop which senses the output voltage
(VO1 pin) and directly feeds the information to a fast comparator stage. This comparator sets the switching
frequency, which is constant for steady state operating conditions, and provides immediate response to dynamic
load changes. In order to achieve accurate DC load regulation, a voltage feedback loop is used. The internally
compensated regulation network achieves fast and stable operation with small external components and low
ESR capacitors. The DCS-Control™ topology supports PWM (Pulse Width Modulation) mode for medium and
high load conditions and a Power Save Mode at light loads. Since DCS-Control™ supports both operation modes
within one single building block, the transition from PWM to Power Save Mode is seamless with minimum output
voltage ripple. The step-down converter offers both excellent DC voltage and superior load transient regulation,
combined with low output voltage ripple, minimizing interference with RF circuits.
7.3.1.2 Output Voltage Selection with pins VSEL1-VSEL3
The step-down converter doesn't require an external resistor divider network to program the output voltage. The
device integrates a high impedance feedback resistor divider network that is programmed by the pins VSEL1-3. It
supports an output voltage range from 1.0 V to 3.0 V. The output voltage is programmed according to Table 2.
The output voltage can be changed during operation. This can be used for simple dynamic output voltage
scaling.
10
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Feature Description (continued)
7.3.1.3 CTRL / Output Load
With the CTRL pin set to high, the integrated loadswitch is activated and connects the LOAD pin to the VO1 pin
to power up an additional sub-system. The load switch is slew rate controlled to support soft switching and not to
impact the regulated output VO1. If CTRL pin is pulled to GND, the LOAD pin is disconnected from the VO1 pin
and internally connected to GND by an internal discharge switch. The CTRL pin can be controlled by a micro
controller.
7.3.1.4 Output Discharge At Pins VO1 And LOAD
Both the VO1 pin and the LOAD pin feature a discharge circuit to connect each rail to GND, once they are
disabled. This feature prevents residual charge voltages on capacitors connected to these pins, which may
impact proper power up of the main- and sub-system. With CTRL pin pulled to low, the discharge circuit at the
LOAD pin becomes active. With the EN pin pulled to low, the discharge circuits at both pins VO1 and Load are
active. The discharge circuits of both rails VO1 and LOAD are associated with the UVLO comparator as well.
Both discharge circuits become active once the input voltage VIN has dropped below the UVLO comparator
threshold VTH_UVLO- and the UVLO comparator triggers.
7.3.1.5 Undervoltage Lockout UVLO
The UVLO circuit shuts down the device if the input voltage VIN drops to typical 1.9 V. The device starts up at an
input voltage of typically 2.1 V.
7.3.1.6 Short Circuit Protection
The step-down converter integrates a current limit on the high side, as well on the low side MOSFETs to protect
the device against overload or short circuit conditions. The peak current in the switches is monitored cycle by
cycle. If the high side MOSFET current limit is reached, the high side MOSFET is turned off and the low side
MOSFET is turned on until the switch current decreases below the low side MOSFET current limit. Once the low
side MOSFET current limit trips, the low side MOSFET is turned off and the high side MOSFET turns on again.
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Feature Description (continued)
7.3.2 Step-Up Converter Device
SW2
VIN
VO2
Gate Driver
OVP
Rectifier
NMOS
Switch
Softstart&
Current Limit
Control
VO2
Pre-charge,
Short Circuit Protection
Load Disconnect
FB
PFM/PWM
Control
Isolation
MOSFET
Fixed VOUT
Detector
Reference System
BM
VREF
BM = low
VREF = 795mV
Mode
Selection
EN2/PWM
PWM to
VREF Converter
VREF = DPWM * 200mV
BM = high
Error
Amplifier
FB
GND2
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Figure 5. Block Diagram Step-Up Converter
The step-up converter is designed for applications requiring voltages up to 15 V from an Li-Ion battery and tiny
solution size such as PMOLED displays or LED back light for small size LCD displays. The step-up converter
operates in two different modes, either as constant output voltage step-up converter operating with 0.8 V internal
reference or as a constant output current step-up converter operating with a reduced internal reference voltage of
200mV. The block integrates power switch, input/output isolation switch, and power diode.
7.3.2.1 Under-Voltage Lockout
See section Undervoltage Lockout UVLO description for the Step-Down Converter.
7.3.2.2 Output Disconnect
One common issue with conventional step-up regulators is the conduction path from input to output even when
the device is disabled. It creates three problems, which are inrush current during start-up, output leakage current
during shutdown and excessive over load current. The step-up converter has an integrated isolation (load
disconnect) switch, which is turned off under shutdown mode and over load conditions, thereby opening the
current path to the output VO2. Thus the device can truly disconnect the load from the input voltage and
minimize the leakage current during shutdown mode.
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Feature Description (continued)
7.3.2.3 12 V Fixed Output Voltage
The step-up converter features an internal default 12-V output voltage setting by connecting the FB pin to the
VIN pin. Therefore no external resistor divider network is required minimizing the total solution size.
7.3.2.4 Mode Selection With Pin BM
The step-up converter can operate in two different modes. With pin BM = low the device regulates to a constant
output voltage; with BM = high, the device can regulate a constant output current. Further details are in section
Constant-Current Step-Up Mode Operation and section Constant-Voltage Step-Up Mode Operation. The
operation mode needs to be selected before the device is enabled. Pin BM may not be changed during
operation.
7.3.2.5 Output Overvoltage Protection
When the output voltage exceeds the OVP threshold of 17.7 V, the device stops switching. Once the output
voltage falls 0.8 V below the OVP threshold, the device resumes operation again.
7.3.2.6 Output Short Circuit Protection
The step-up converter starts to limit the output current whenever the output voltage drops below 4 V. When the
VOUT pin is shorted to ground, the output current is limited. This function protects the device from being
damaged when the output is shorted to ground.
7.3.2.7 PWM to Analog Converter AT PIN EN2/PWM
In constant current step-up mode operation two control functions are associated with the pin EN2/PWM:
a) Enable/ disable of the step-up converter
b) PWM to analog conversion to scale the internal reference voltage.
The internal reference voltage scales proportional with the duty cycle of the PWM signal applied at the pin
EN2/PWM. More details in section Constant-Current Step-Up Mode Operation.
7.4 Device Functional Modes
7.4.1 Step-Down Converter
7.4.1.1 Enable and Shutdown
The step-down converter is turned on with EN1 = high. With EN1 = low the step-down converter is turned off.
This pin must be terminated.
7.4.1.2 Power Save Mode Operation
At light loads, the device operates in Power Save Mode. The switching frequency varies linearly with the load
current. In Power Save Mode the device operates in PFM (Pulse Frequency Modulation) that generates a single
switching pulse to ramp up the inductor current and recharges the output capacitor, followed by a sleep period
where most of the internal circuits are shutdown to achieve lowest operating quiescent current. During this time,
the load current is supported by the output capacitor. The duration of the sleep period depends on the load
current and the inductor peak current. During the sleep periods, the current consumption is reduced to 360 nA.
This low quiescent current consumption is achieved by an ultra low power voltage reference, an integrated high
impedance feedback divider network and an optimized Power Save Mode operation.
7.4.1.3 PWM Mode Operation
At moderate to heavy load currents, the device operates in PWM mode with continuos conduction. The switching
frequency is up to 1.6 MHz with a controlled frequency variation depending on the input voltage and load current.
If the load current decreases, the converter seamlessly enters Power Save Mode to maintain high efficiency
down to very light loads.
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Device Functional Modes (continued)
7.4.1.4 Device Start-up and Soft Start
The step-down converter has an internal soft start to minimize inrush current and input voltage drop during startup. Once the device is enabled the device starts switching after a typical delay time of 1 ms. Then the soft start
time of typical 700 μs begins with a reduced current limit of typical 150mA. When this time expires the device
enters full current limit operation.
7.4.1.5 Automatic Transition Into 100% Mode
Once the input voltage comes close to the output voltage, the DC/DC converter stops switching and enters 100%
duty cycle operation. It connects the output VOUT via the inductor and the internal high side MOSFET switch to
the input VIN, once the input voltage VIN falls below the 100% mode enter threshold, VTH_100-. The DC/DC
regulator is turned off, switching stops and therefore no output voltage ripple is generated. Because the output is
connected to the input, the output voltage follows the input voltage minus the voltage drop across the internal
high side switch and the inductor. Once the input voltage increases and trips the 100% mode exit threshold,
VTH_100+ , the DC/DC regulator turns on and starts switching again.
7.4.2 Step-Up Converter
7.4.2.1 Enable and Shutdown
The device is turned on with EN2/PWM = high. With EN2/PWM = low the device enters shutdown mode. In
constant current step-up mode (BM = high) the pin EN2/PWM has to be pulled to low level for longer than tDim_Off
max to enter shutdown mode. This pin must be terminated.
7.4.2.2 Soft Start
The step-up converter begins soft start when the EN2/PWM pin is pulled high. At the beginning of the soft start
period, the isolation FET is turned on slowly to charge the output capacitor with 30-mA current for about 6 ms.
This is called the pre-charge phase. The output is charged up to the level of the input voltage VIN. After the precharge phase, the device starts switching and the output voltage ramps up. This is called switching soft start
phase. An internal soft start circuit limits the peak inductor current.
7.4.2.3 Power Save Mode
The step-up converter integrates a power save mode with pulse frequency modulation (PFM) to improve
efficiency at light load. When the load current decreases, the inductor peak current set by the output of the error
amplifier declines to regulate the output voltage. When the inductor peak current hits the low limit of 240 mA, the
output voltage will exceed the set voltage as the load current decreases further. The device enters power save
mode once the FB voltage exceeds the PFM mode threshold, which is 1% above the nominal output voltage. It
stops switching, the load is supplied by the output capacitor and the output voltage begins to decline. When the
FB voltage falls below the PFM mode threshold voltage, the device starts switching again to ramp up the output
voltage.
14
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Device Functional Modes (continued)
Output
Voltage
PFM mode at light load
PFM mode threshold
1.01 x VOUT_NOM
VOUT_NOM
PWM mode at heavy load
Figure 6. Output Voltage in PFM and PWM Mode
7.4.2.4 PWM Mode
The step-up converter uses a quasi-constant 1.0-MHz frequency pulse width modulation (PWM) at moderate to
heavy load current. Based on the input voltage to output voltage ratio, a circuit predicts the required off-time. At
the beginning of the switching cycle, the NMOS switching FET is turned on. The input voltage is applied across
the inductor and the inductor current ramps up. In this phase, the output capacitor is discharged by the load
current. When the inductor current hits the current threshold that is set by the output of the error amplifier, the
PWM switch is turned off, and the power diode is forward-biased. The inductor transfers its stored energy to
charge the output capacitor and supply the load. When the off-time is expired, the next switching cycle starts
again. The error amplifier compares the FB pin voltage with an internal reference voltage, and its output
determines the inductor peak current.
7.4.2.5 Constant-Current Step-Up Mode Operation
With pin BM = high the converter can regulate to a constant output current. The internal reference voltage is
therefore reduced to 200mV. In order to regulate a constant output current, a sense resistor has to be connected
between pin FB and GND, see Figure 7. The device features in this operation mode a PWM to analog converter
at pin EN2/PWM. The internal reference voltage is scaled according to the duty cycle of the PWM signal applied
to pin EN2/PWM, see Figure 8. When the pin EN2/PWM is pulled low longer than tDim_OFF max, the step-up
converter enters shutdown mode. The constant output current IOUT2 can be calculated according equations
Equation 1 and Equation 2.
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Device Functional Modes (continued)
Step up Converter
VIN
L2
SW2
VBAT
IOUT
VO2
PFM/PWM
Control
COUT2
VFB
BM
CIN
Error
Amplifier
VFB
FB
VREF
RSense
tDim_On
PWM to analog converter
VREF = DPWM * 200mV
EN2/PWM
tDim_Off
PWM
GND2
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Figure 7. Step-Up Converter in Constant-Current Operation Mode
EN2/PWM
PWM Dimming
Device
Shutdown
tDim_On tDim_OFF
tDim_OFF >
tDim_OFF max
200
160
VFB in
mV
120
80
D=
tDim_On
tDim_On + tDim_OFF
40
20
40
60
80
100
D in %
Figure 8. EN2/PWM Pin Function
I OUT 2 =
VFB
RSense
IOUT2 = DPWM
16
(1)
200 mV
×
RSense
(2)
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Device Functional Modes (continued)
7.4.2.6 Constant-Voltage Step-Up Mode Operation
With pin BM = low the converter operates as a constant output voltage step-up converter. The internal reference
voltage is set to 795 mV. A feedback resistor divider need to be connected between VOUT, FB and GND with its
tap point connected to FB pin. The device provides a fixed set 12 V output voltage if the FB pin is connected to
VIN. In this case no external resistor divider network is needed.
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The TPS62770 is a tiny power solution for wearable applications including a 370 nA ultra low Iq step-down
converter, a slew-rate controlled load switch and a dual-mode step-up converter. The output voltage of the stepdown converter can be selected between 1.0 V and 3.0 V. The output voltage can be changed during operation.
In shutdown mode, the output of the step-down converter is pulled to GND. The integrated load switch is
internally connected to the output of the step-down converter and features slew rate control during turn on phase.
Once turned off, its output is connected to GND. In order to achieve better supply voltage decoupling / noise
reduction a capacitor can be connected on the LOAD output. The RDSON of the load switch and the connected
capacitor form a RC filter.
The dual mode step-up converter can generate a constant output voltage up to 15V, e.g. for PMOLED supply, or
a constant output current, e.g. for LED back light supply. The output voltage can be adjusted up to 15 V with
external resistors, or set to fixed 12 V by connecting the FB pin to VIN. The device features an internal over
voltage protection of 17 V in case the FB node is left open or tight to GND. It includes an internal rectifier and
load disconnect function. When used as constant output current driver, the device offers a PWM to analog
converter to scale down the reference voltage according to the duty cycle of the PWM signal.
The design guideline provides a component selection to operate the device within the recommended operating
conditions.
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8.2 Typical Applications
8.2.1 TPS62770 Step-Down Converter + Load Switch
TPS62770
VIN
CIN
10mF
EN1
DC/DC 1
Step Down Converter
SW1
VOUT1 = 1.8V/300mA
L1 = 2.2mH
VO1
VSEL3
VSEL2
MCU / BLE
COUT1
10mF
VSEL1
Load Output = 1.8V
ON/OFF
CTRL
Load Switch
LOAD
Sensors
L2 = 10mH
VOUT2 = 12V / 30mA
SW2
EN2/PWM
FB
DC/DC 2
Step up converter
VO2
PMOLED
COUT2
10mF
BM
GND1
GND2
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Figure 9. Simplified Schematic – TPS62770 Step-Down Converter Set to 1.8-V Output
8.2.1.1 Design Requirements
The LC output filter should meet the values shown in Table 3.
Table 3. Recommended LC Output Filter Combinations for the Step-Down
Converter
OUTPUT CAPACITOR VALUE [µF] (2)
INDUCTOR VALUE
[µH] (1)
10 µF
√
2.2
(1)
(2)
(3)
(3)
22 µF
√
Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by 20% and 30%.
Capacitance tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by
20% and -50%.
This LC combination is the standard value and recommended for most applications.
8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Setting The Output Voltage Of The Step-Down Converter
The output voltage is set with the VSEL1-3 pins according to Table 2. No further external components are
required.
8.2.1.2.2 Inductor Selection Step-Down Converter
The inductor value affects its peak-to-peak ripple current, the PWM-to-PFM transition point, the output voltage
ripple and the efficiency. The selected inductor has to be rated for its DC resistance and saturation current. The
inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VIN or VOUT and can be
estimated according to Equation 3.
18
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Equation 4 calculates the maximum inductor current under static load conditions. The saturation current of the
inductor should be rated higher than the maximum inductor current, as calculated with Equation 4. This is
recommended because during a heavy load transient the inductor current rises above the calculated value. A
more conservative way is to select the inductor saturation current above the high-side MOSFET switch current
limit, ILIMF.
Vout
1Vin
D IL = Vout ´
L ´ ¦
(3)
ILmax = Ioutmax +
DIL
2
(4)
With:
f = Switching Frequency
L = Inductor Value
ΔIL= Peak to Peak inductor ripple current
ILmax = Maximum Inductor current
In DC/DC converter applications, the efficiency is essentially affected by the inductor AC resistance (i.e. quality
factor) and by the inductor DCR value. Increasing the inductor value produces lower RMS currents, but degrades
transient response. For a given physical inductor size, increased inductance usually results in an inductor with
lower saturation current.
The total losses of the coil consist of both the losses in the DC resistance (RDC) and the following frequencydependent components:
• The losses in the core material (magnetic hysteresis loss, especially at high switching frequencies)
• Additional losses in the conductor from the skin effect (current displacement at high frequencies)
• Magnetic field losses of the neighboring windings (proximity effect)
• Radiation losses
8.2.1.2.3 Input and Output Capacitor Selection
Ceramic capacitors with low ESR values have the lowest output voltage ripple and are recommended. The
output capacitor requires either an X7R or X5R dielectric. Y5V and Z5U dielectric capacitors, aside from their
wide variation in capacitance over temperature, become resistive at high frequencies. At light load currents, the
converter operates in Power Save Mode and the output voltage ripple is dependent on the output capacitor value
and the PFM peak inductor current. A 10 µF ceramic capacitor is recommended as input capacitor.
Table 4 shows a list of tested input/output capacitors.
Table 4. Components for Application Curves – TPS62770 Step-Down Converter + Load Switch
REFERENCE
DESCRIPTION
VALUE
PACKAGE CODE / SIZE
[mm x mm x mm]
MANUFACTURER (1)
CIN
Ceramic capacitor X5R 6.3V,
GRM155R60J106ME11
10 µF
0402 / 1.0 x 0.5 x 0.5
Murata
COUT1
Ceramic capacitor X5R 6.3V,
GRM155R60J106ME11
10 µF
0402 / 1.0 x 0.5 x 0.5
Murata
L1
Inductor DFE201610C
2.2 µH
2.0 x 1.6 x 1.0
Toko
(1)
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90
90
80
80
70
70
60
60
Efficiency [%]
Efficiency [%]
8.2.1.3 Application Curves – TPS62770 Step-Down Converter + Load Switch
50
40
30
VIN = 4.2V
10
VIN = 5.0V
0
0.001
0.01
0.1
1
10
30
20
VIN = 4.2V
10
40
VIN = 3.6V
VIN = 3.6V
20
50
VIN = 5.0V
0
0.001
100
0.01
0.1
10
100
100
90
90
Efficiency [%]
80
70
60
80
70
60
VIN = 3.6V
VIN = 3.6V
50
VIN = 4.2V
40
VIN = 4.2V
50
VIN = 5.0V
VIN = 5V
30
0.001
0.01
0.1
1
100
Figure 11. Efficiency vs. IOUT, VOUT1 = 1.2 V
Figure 10. Efficiency vs. IOUT, VOUT1 = 1.0 V
Efficiency [%]
1
IOUT [mA]
IOUT [mA]
10
40
0.001
100
0.01
0.1
1
10
100
IOUT [mA]
IOUT [mA]
Figure 13. Efficiency vs. IOUT, VOUT1 = 3.0 V
Figure 12. Efficiency vs. IOUT, VOUT1 = 1.8 V
1.890
1400
1.872
1200
1.854
1.836
VOUT1 [V]
fSW [kHz]
1000
800
VIN = 3.0V
600
VIN = 3.6V
400
100
150
200
1.782
1.764
1.746
VIN = 5V
1.728
0
50
1.800
VIN = 4.2V
200
0
1.818
250
300
1.710
0.01
IOUT1 [mA]
0.10
1.00
10.00
100.00
IOUT1 [mA]
Figure 14. FSW vs. IOUT1, VOUT1 = 1.1 V
20
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
VIN = 5V
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Figure 15. VOUT1 = 1.8 V vs IOUT1
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VIN = 3.6 V
VOUT = 1.2 V
IOUT = 50 µA
Figure 16. Typical Operation in Power Save Mode
VIN = 3.6 V
VOUT = 1.2 V
IOUT = 50 mA
Figure 18. Typical Operation in Power Save Mode
VIN = 3.6 V
VOUT = 1.2 V
IOUT = 5 mA to 200 mA
1 µs Rise/Fall Time
Figure 20. Load Transient Performance
VIN = 3.6 V
VOUT = 1.2 V
IOUT = 1 mA
Figure 17. Typical Operation in Power Save Mode
VIN = 3.6 V
VOUT = 1.2 V
IOUT = 200 mA
Figure 19. Typical Operation in PWM Mode
VIN = 3.6 V
VOUT = 1.2 V
IOUT = 5 mA to 200 mA
Sinusoidal IOUT Sweep
Figure 21. AC Load Regulation Performance
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VIN = 3.6 V
VOUT = 1.8 V
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IOUT = 0 mA
VIN = 3.6 V
VOUT = 1.8 V
IOUT = 0 mA
EN Altered from Low to High
Figure 22. Startup After EN High
VIN = 0 V to 3.6 V in 100 µs
VOUT = 1.8 V
EN = VIN
IOUT = 0 mA
Figure 23. VOUT Ramp Up
VIN = 3.6 V
VOUT = 1.8 V
Figure 24. VIN Ramp Up/Down
VIN = 3.6 V
VOUT = 1.8 V
IOUT = 0 mA
Figure 25. Output Discharge
IOUT1 = 5 mA
RLOAD = 150 Ω
Figure 26. Output Load Enable/Disable
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8.2.2 TPS62770 Step-Up Converter with Adjustable Output Voltage (9 V to 15 V)
TPS62770
VIN
CIN
10mF
EN1
DC/DC 1
Step-Down Converter
L1 = 2.2 mH
SW1
VOUT1 = 1.8 V/300 mA
MCU / BLE
VO1
COUT1
10 mF
VSEL3
VSEL2
VSEL1
Load Output = 1.8 V
ON/OFF
CTRL
Load Switch
LOAD
Sensors
VOUT2 = 9.6 V
L2 = 10 mH
SW2
EN2/PWM
VO2
DC/DC 2
Step-Up Converter
PMOLED
R1 =
910 kΩ
FB
COUT2
10 mF
R2 =
82 kΩ
BM
GND1
GND2
Copyright © Texas Instruments Incorporated
Figure 27. Schematic for Step-Up Converter with Adjustable Output Voltage (9V-15V)
8.2.2.1 Design Requirements
The LC output filter should meet the values shown in Table 5.
Table 5. Recommended LC Output Filter Combinations for Step-Up Converter
OUTPUT CAPACITOR VALUE [µF] (2)
INDUCTOR
VALUE
[µH] (1)
VOUT
10
9 V –15 V
(1)
(2)
(3)
IOUT
10 µF
(IOUT ≤ 30 mA)
(IOUT ≤ 100 mA)
√
2 x 10µF
√
√ (3)
Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by 20% and 30%.
Capacitance tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by
20% and -50%.
This LC combination is the standard value and recommended for most applications.
8.2.2.2 Detailed Design Procedure
8.2.2.2.1 Programming the Output Voltage Of The Step-Up Converter
There are two ways to set the output voltage of the step-up converter. When the FB pin is connected to the input
voltage, the output voltage is fixed to 12 V. This function reduces the external components to minimize the
solution size. The second way is to use an external resistor divider to set the desired output voltage.
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By selecting the external resistor divider R1 and R2, as shown in Equation 5, the output voltage is programmed
to the desired value. When the output voltage is regulated, the typical voltage at the FB pin is VREF of 795 mV.
§V
R1 ¨ OUT
© VREF
·
1¸ u R2
¹
(5)
Where:
VOUT is the desired output voltage
VREF is the internal reference voltage at the FB pin
8.2.2.2.2 Inductor Selection for TPS62770 Step-Up Converter
The step-up converter is optimized to work with an inductor values of 10 µH. Follow Equation 6 to Equation 8 to
calculate the inductor’s peak current for the application. To calculate the current in the worst case, use the
minimum input voltage, maximum output voltage, and maximum load current of the application. To have enough
design margin, choose the inductor value with -30% tolerance, and a low power-conversion efficiency for the
calculation.
In a step-up regulator, the inductor dc current can be calculated with Equation 6.
VOUT u IOUT
IL(DC)
VIN u K
(6)
Where:
VOUT = output voltage
IOUT = output current
VIN = input voltage
η = power conversion efficiency, use 80% for most applications
The inductor ripple current is calculated with the Equation 7 for an asynchronous step-up converter in continuous
conduction mode (CCM).
VIN u VOUT 0.8V VIN
'IL(P P)
L u fSW u VOUT 0.8V
(7)
Where:
ΔIL(P-P) = inductor ripple current
L = inductor value
f SW = switching frequency
VOUT = output voltage
VIN = input voltage
Therefore, the inductor peak current is calculated with Equation 8.
'IL P P
IL P IL DC
2
(8)
The following inductor series from different suppliers have been used:
Table 6. List Of Inductors
CONVERTER
Step-up
(1)
24
SUPPLIER ( Output
1)
Current IOUT2
DIMENSIONS
[mm3]
INDUCTOR
TYPE
10
2.0x1.6x1.2
VLS201610
TDK
< 30mA
10
3.0 x 2.5 x 1.5
VLS302515
TDK
< 100mA
INDUCTANCE [µH]
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8.2.2.2.2.1 Example Step-Up Converter with 12-V Fixed Output
TPS62770
VIN
CIN
10mF
EN1
DC/DC 1
Step Down Converter
SW1
VOUT1 = 1.8V/300mA
L1 = 2.2mH
VO1
VSEL3
VSEL2
MCU / BLE
COUT1
10mF
VSEL1
Load Output = 1.8V
ON/OFF
Load Switch
CTRL
LOAD
Sensors
L2 = 10mH
VOUT2 = 12V / 30mA
SW2
EN2/PWM
FB
DC/DC 2
Step up converter
VO2
PMOLED
COUT2
10mF
BM
GND1
GND2
Figure 28. Schematic for a Step-Up Converter with Fixed 12-V Output
Table 7. Components for Application Curves for Step-Up Converter
REFERENCE
DESCRIPTION
VALUE
PACKAGE CODE / SIZE
[mm x mm x mm]
MANUFACTURER (1)
CIN
Ceramic capacitor X5R 6.3V,
GRM155R60J106ME11
10 µF
0402 / 1.0 x 0.5 x 0.5
Murata
COUT2
Ceramic capacitor X5R 25V,
GRM188R61E106MA73
2 x 10 uF
0603 / 1.6 x 0.8 x 0.8
Murata
L2
Inductor VLS302515
10 µH
3.0 x 2.5 x 1.5
TDK
(1)
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90
90
80
80
70
70
60
60
Efficiency [%]
Efficiency [%]
8.2.2.3 Application Curves for Step-Up Converter
50
40
30
VIN = 5.0V
VIN = 4.2V
VIN = 3.6V
VIN = 3.0V
20
10
0
1
50
40
30
VIN = 4.2V
VIN = 3.6V
VIN = 3V
VIN = 5.0V
20
10
0
1
10
10
IOUT [mA]
C001
Figure 30. Efficiency vs. IOUT, VOUT = 12 V
12.60
200
12.48
180
12.36
160
12.24
140
IOUT2 max [mA]
VO2 [V]
Figure 29. Efficiency vs. IOUT, VOUT = 15 V
12.12
12.00
11.88
120
100
80
11.76
VIN = 4.2V
11.64
VIN = 3.6V
40
11.52
VIN = 3.0V
20
60
VO2 = 12V
VO2 = 15V
VO2 = 9V
0
11.40
0.1
1
10
100
1000
2.5
3
IOUT2 [mA]
Figure 31. VOUT2 = 12 V vs IOUT2
VIN = 3.6 V
VOUT = 12 V
3.5
4
4.5
5
5.5
VIN [V]
TA = 25°C
L = 10 µH
IOUT2 = 2 mA
L = 10 µH
Typical Switch Current Limit ILIM_SW
IOUT2 max @ -3% VOUT Drop
COUT2 = 2x 10 µF
Figure 32. Maximum Output Current vs VIN for Typical
ILIMSW
VIN = 3.6 V
VOUT = 12 V
Figure 33. Typical Operation PFM Mode
26
100
IOUT [mA]
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IOUT2 = 30 mA
L = 10 µH
Figure 34. Typical Operation PWM Mode
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VIN = 3.6 V
VOUT = 12 V
IOUT2 = 0 mA to 20 mA
L = 10 µH
VIN = 3.6 V
VOUT = 12 V
Figure 35. AC Load Regulation Performance
RLOAD = 1 kΩ
L = 10 µH
Figure 36. Startup after EN High
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8.2.3 Step-Up Converter with Constant 5-V Output Voltage
TPS62770
VIN
CIN
10mF
DC/DC 1
Step-Down Converter
EN1
VOUT1
= 1.8 V/300 mA
SW1
L1 = 2.2 mH
MCU / BLE
VO1
COUT1
10 mF
VSEL3
VSEL2
VSEL1
Load Output = 1.8 V
ON/OFF
Load Switch
CTRL
LOAD
Sensors
VOUT2
= 5 V/200 mA
L2 = 4.7mH
SW2
VO2
EN2/PWM
DC/DC 2
Step-Up Converter
R1 =
1 MΩ
FB
COUT2
2 x 10 mF
R2 =
191 kΩ
BM
GND1
GND2
Copyright © 2016, Texas Instruments Incorporated
Figure 37. Step-Up Converter Providing 5V VOUT2
8.2.3.1 Design Requirements
The LC output filter should meet the values shown in Table 8. For 5V Output voltage an inductor value of 4.7µH
should be used for loop stability.
Table 8. Recommended LC Output Filter Combinations for Step-Up Converter
VOUT
IOUT
4.7
5V
(IOUT ≤ 200 mA)
(1)
(2)
(3)
28
OUTPUT CAPACITOR VALUE [µF] (2)
INDUCTOR
VALUE
[µH] (1)
10 µF
2 x 10µF
√ (3)
Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by 20% and 30%.
Capacitance tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by
20% and -50%.
This LC combination is the standard value and recommended for most applications.
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8.2.3.2 Detailed Design Procedure
For setting the output voltage, see Programming the Output Voltage Of The Step-Up Converter
Table 9. Components for Application Performance Curves
REFERENCE
DESCRIPTION
VALUE
PACKAGE CODE / SIZE
[mm x mm x mm]
MANUFACTURER (1)
CIN
Ceramic capacitor X5R 6.3V,
GRM155R60J106ME11
10 µF
0402 / 1.0 x 0.5 x 0.5
Murata
COUT2 (2x)
Ceramic capacitor X5R 6.3V,
GRM188R60J106ME84
10uF
0603 / 1.6 x 0.8 x 0.8
Murata
L2
Inductor VLS302515
4.7 µH
3.0 x 2.5 x 1.5
TDK
(1)
See Third-party Products Disclaimer
8.2.3.3 Application Performance Curves
90
80
Efficiency [%]
70
60
50
40
30
VIN = 3.0V
20
VIN = 3.6V
10
VIN = 4.2V
0
1
10
100
IOUT [mA]
Figure 38. Efficiency vs. IOUT, VOUT = 5.0 V
Figure 39. Transient Response VOUT2 = 5 V
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8.2.4 Typical Step Up Converter with Constant Output Current
Step up Converter
VIN
PFM/PWM
Control
L2 =
10mH
SW2
VBAT
COUT2
= 10mF
VFB
BM
CIN
= 10mF
IOUT
VO2
Error
Amplifier
VREF
FB
VFB
RSense
= 20W
tDim_On
EN2/PWM
tDim_Off
PWM to analog converter
VREF = DPWM * 200mV
PWM
GND2
Copyright © 2016, Texas Instruments Incorporated
Figure 40. Step-Up Converter with Constant Output Current
8.2.4.1 Design Requirements
The step-up converter is configured to operate as a constant current driver e.g. to power 3 to 4 white LED's in a
string. The maximum current through the string is set by the sense resistor RSense as shown in Figure 40 To
minimize the losses in the sense resistor, the device features a 200mV internal reference, which is enabled by
connecting the BM pin to high level. This section describes an application delivering 10mA through an LED string
with 4 LED's which is suitable for small display used in wearable applications. See also TPS62770 Step-Up
Converter with Adjustable Output Voltage (9 V to 15 V) section Design Requirements.
8.2.4.2 Detailed Design Procedure
8.2.4.2.1 Setting the Output Current
The Sense resistor to set the maximum output current can be calculated according to Equation 9 The output
current IOUT2 can be reduced by applying a PWM signal at pin EN2/PWM according to Equation 10
200 mV
RSense =
IOUT2
(9)
IOUT2 = DPWM ×
200 mV
RSense
(10)
Where:
RSense = sense resistor in [Ω]
IOUT2 = output current in [mA]
DPWM = Dutycycle of the PWM singal at pin EN2/PWM
8.2.4.2.2 Inductor Selection
See Inductor Selection for TPS62770 Step-Up Converter
30
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Table 10. Components for Application Curves
REFERENCE
DESCRIPTION
VALUE
PACKAGE CODE / SIZE
[mm x mm x mm]
MANUFACTURER (1)
CIN
Ceramic capacitor X5R 6.3V,
GRM155R60J106ME11
10 µF
0402 / 1.0 x 0.5 x 0.5
Murata
COUT2
Ceramic capacitor X5R 25V,
GRM188R61E106MA73
10 uF
0603 / 1.6 x 0.8 x 0.8
Murata
(1)
L2
Inductor VLS302515
10 µH
3.0 x 2.5 x 1.5
TDK
RSense
Resistor 1%
20 Ω
0402/ 1.0 x 0.5 x 0.5
Vishay
D1-D4
LED LTW-E670DS
n/a
Lite ON
See Third-party Products Disclaimer
8.2.4.3 Application Curves
VIN = 3.6 V
EN2/PWM = High
D = 100%, ILED = 10 mA
RSense= 20 Ω
4 LEDs in Series
L = 10 µH
Figure 41. Constant Current Operation with EN2/PWM =
100% D
VIN = 3.6 V
tDim_On = 75 µs, tDim_Off = 75 µs
D = 50%, TDIim = 140 µs, ILED = 5 mA
RSense= 20 Ω
4 LEDs in Series
L = 10 µH
Figure 42. Constant Current with EN2/PWM = 50% D
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10
9
8
ILED [mA]
7
6
5
4
3
2
4 LED
1
3 LED
0
0
20
40
60
80
100
D [%]
VIN = 3.6 V
tDim_On = 15 µs, tDim_Off = 135 µs
D = 10%, TDIim = 140 µs, ILED = 1 mA
RSense= 20 Ω
4 LEDs in Series
L = 10 µH
VIN = 3.6 V
TA = 25°C
TDIim = 50 µs (F = 20 kHz)
Figure 43. Constant Current with EN2/PWM = 10% D
RSense= 20 Ω
LED's in String Configuration
L = 10 µH
Figure 44. Constant Current vs D
9 Power Supply Recommendations
The power supply must provide a current rating according to the supply voltage, output voltage and output
current of the TPS62770.
10 Layout
10.1 Layout Guidelines
•
•
•
•
•
•
32
As for all switching power supplies, the layout is an important step in the design. Care must be taken in board
layout to get the specified performance.
If the layout is not carefully done, the regulator could show poor line and/or load regulation, stability issues as
well as EMI problems and interference with RF circuits.
It is critical to provide a low inductance, impedance ground path. Therefore, use wide and short traces for the
main current paths.
The input capacitor should be placed as close as possible to the IC pins VIN and GND. The output capacitors
should be placed close between VO1/2 and GND pins.
The VO1/2 line should be connected to the output capacitor and routed away from noisy components and
traces (e.g. SW line) or other noise sources.
See Figure 45 and Figure 46 for the recommended PCB layout.
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10.2 Layout Example
VOUT2
(Step Up Converter)
COUT2
GND
L2
VIN
GND2
SW2
VO2
VSEL3
BM
VSEL2
EN2/
PWM
FB
SW1
EN1
VIN
GND1
TPS62770
VSEL1 CTRL
VO1
LOAD
CIN
COUT1 VOUT1
(Step Down Converter)
L1
Figure 45. Recommended PCB Layout with 12 V Fixed VOUT2
VOUT2
COUT2
(Step Up Converter)
R1
GND
L2
VIN
GND2
SW2
VO2
VSEL3
BM
VSEL2
EN2/
PWM
FB
SW1
EN1
VIN
GND1
R2
VSEL1 CTRL
VO1
LOAD
TPS62770
CIN
COUT1
L1
GND
VOUT1
(Step Down Converter)
Figure 46. Recommended PCB Layout with Adjustable VOUT2
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Documentation Support
11.2.1 Related Documentation
See also TPS62770EVM-734 Evaluation Module User's Guide, SLVUAO2 and application note Accurately
measuring efficiency of ultralow-IQ devices, SLYT558.
11.3 Trademarks
DCS-Control is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
34
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TPS62770YFPR
ACTIVE
DSBGA
YFP
16
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
62770
TPS62770YFPT
ACTIVE
DSBGA
YFP
16
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
62770
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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