QUICK START GUIDE FOR
DC1140A
LTC3567EUF: High Efficiency
USB Power Manager Plus 1A
Buck-Boost Converter with I
2
C Control
DESCRIPTION
Demonstration Circuit 1140A is a high efficiency USB
Power/Li-Ion battery manager plus a 1A Buck-Boost
regulator. The LTC3567EUF is available in a 24-pin
(4mm × 4mm) QFN surface mount package.
L
, LTC, Burst Mode, Bat-Track are registered trademarks of Linear Technology Corporation.
PowerPath and SwitcherCAD are trademarks of Linear Technology Corporation. Other product
names may be trademarks of the companies that manufacture the products.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL
VBUS
LDO3V3
VBAT
I
BAT
VOUT1
PARAMETER
Bus Input Voltage Range
3.3V LDO Output Voltage Range
Battery Float Voltage
Battery Charge Current
Regulator 1 Output Voltage
CONDITIONS
MIN
4.35
3.1
4.15
485
3.15
TYP
MAX
5.5
3.4
4.23
515
3.45
UNITS
V
V
V
mA
V
Constant Voltage Mode
Constant Current Mode, R
PROG
= 2.00k
IOUT1 ≤ 1000mA
OPERATING PRINCIPLES
The LTC3567EUF is a full featured USB Power Manager
and Li-Ion battery charger with a 1A Buck-Boost DC/DC
regulator. The LTC3567EUF has an I
2
C interface that al-
lows adjustment of the Buck-Boost output voltage, oper-
ating mode, and USB power management control. The
Bat-Track™ battery charger pre-regulator ensures the
charger operates at the highest possible efficiency.
The LTC3567EUF is composed of 6 functional blocks, all
working together: USB Power Manager, Pre-regulator,
Battery Charger, Ideal Diode, 1A Buck-Boost DC/DC regu-
lator, and I
2
C.
USB Power Manager
The USB Power Manager is used to manage the load that
the LTC3567EUF system presents to the USB interface.
The load current can be programmed by changing the
CLPROG resistor (R2), and by setting the operating mode
to 1X, 5X or 10X with the I
2
C interface.
Buck-Boost Regulator Efficiency
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
Pre-Regulator
The pre-regulator is a high efficiency buck regulator that
produces a voltage at VOUT equal to the battery voltage
plus 0.3V. By reducing the voltage across the charger to
0.3V the dissipation in the charger is greatly reduced, as
compared with a linear charger.
Battery Charger
The battery charger operates in constant current mode,
until the battery voltage rises to approximately the FLOAT
voltage, of 4.2V, and then the charger switches to con-
stant voltage mode.
The charge current is programmed by the PROG resistor
(R3), and has been set to 500mA, on DC1140A, with a
2.00kΩ resistor. The battery charger implements trickle
charging, for initial battery voltages less than 2.85V. It
also implements a charge termination timeout of 4 hours,
and a bad cell charging timeout of 30 minutes. An NTC
input is used to determine if the battery temperature is
suitable for charging, too hot or too cold.
The statuses of the charger, as well as any faults, are sig-
naled with the
CHRG
pin.
Ideal Diode
The Ideal Diode block is composed of an internal Ideal
Diode implemented with an on die MOSFET, as well as a
MOSFET gate driver that allows the use of a parallel ex-
ternal MOSFET.
When the voltage on VOUT drops more than 15mV below
the voltage at BAT, the Ideal Diode becomes active. This
will happen when VBUS is not present, or the load on
VOUT exceeds the power available from VBUS.
1A Buck-Boost DC/DC regulator
The Buck-Boost DC/DC regulator provides a regulated
output that can be above and below the input voltage.
The battery voltage will vary from VFLOAT (4.2V) to as
low as 2.5V. The Buck-Boost regulator can supply a
regulated 3.3V output over this entire battery voltage
range.
The Buck-Boost is implemented with a full H-bridge
switch, and proprietary control algorithm.
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A
LTC3567EUF
I C Interface
The I
2
C interface is a 100kHz, write only serial interface
that allows control of the USB input current limit, battery
charger on/off, Buck-Boost regulator (VOUT1) on/off,
Buck-Boost regulator operating mode, and Buck-Boost
output voltage via an internal 4 bit DAC.
VOUT1
EN1
Figure 1. VOUT1 startup
IOUT1 = 100mA
Figure 2. SWAB1 switching waveform
IOUT1 = 100mA
Figure3. SWCD1 switching waveform
2
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A
LTC3567EUF
APPLICATIONS INFORMATION
The parasitic inductance in some USB cables may cause
the VUSB voltage to overshoot at plug in. If this is the
case it is recommended that the network of C1, R1 and
C2 be added to the board to damp out this overshoot.
While, at first glance, it may appear that C1 + C2 exceeds
the USB specification for capacitive load on VUSB, in fact
this is not the case. For most MLCC capacitors, with
X7R/X5R dielectric the capacitance will be below 4.7μF,
for DC biases of 5V.
The battery charger must see low impedance to ground,
which is the case when a battery is attached. In the event
that a battery emulator is being used, or the impedance to
ground is above 0.5Ω, the circuit of C7 and R14-16 is
recommended.
The Buck-Boost regulator should be compensated with a
Type III compensator, as shown on the schematic. The
Buck, Buck-Boost and pure Boost regions of operation
have different poles/zeroes and PWM gains. In particular,
the Buck-Boost and pure Boost regions have a RHP zero,
that must be accommodated.
It is recommended that the stabilization be verified in all
three regions of operation, with minimum and maximum
load.
The /CHRGEN and EN1 pins are wire OR’ed with the cor-
responding bits from the I
2
C channel. Consequently, if
they are high the battery charger will be disabled and
VOUT1 will be enabled. This is true regardless of the
state of the I
2
C bits. If control of the battery charger and
VOUT1 through the I
2
C bits is desired, please ensure that
these pins are held low.
3
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A
LTC3567EUF
SOFTWARE GUI
The DC1140A Demo Circuit can be controlled from a
software GUI. Most of the features of the LTC3567EUF
are only accessible via the I
2
C channel.
When the QuickEval program is active and a DC590
with a DC1140A connected and attached to the USB
cable, the “LTC3567” form should automatically pop
up and be fully operational:
Battery charger button
If enabled (default) the battery charger in the LTC3567
will be enabled, and vice versa.
VOUT1 buttons
Enable or disable VOUT1. This button is only func-
tional if the EN1 pin is held low.
Buck-Boost Regulator mode
Sets the mode of operation of the Buck-Boost regula-
tor.
Buck-Boost Regulator slider
Allow control of Buck-Boost regulator output voltage
by adjusting the reference DAC.
Buck-Boost Regulator output and reference voltage
These are not writeable, but reflect the current state of
the reference DAC, and feedback resistors.
Change feedback divider resistor values button
This opens the form:
SOFTWARE OPERATION
The software GUI automatically opens the control
panel shown above. This control panel allows control
of most major functions of the LTC3567. Please note
that the EN1, and /CHRGEN signals are wire OR’ed
with the corresponding bits from the I
2
C channel.
Consequent to this, if either is high, the corresponding
bits of the I
2
C channel will appear to be inoperative.
Register A and Register B display
These are not writeable and are provided as a pro-
gramming aid. The current value of the I
2
C A and B
registers are displayed.
Update button
Forces an immediate update of the I
2
C registers.
Autoupdate button
If enabled (default), the I
2
C channel will update when-
ever something is changed.
This form allows the feedback resistor divider network
on the Buck-Boost regulator to be changed. The in-
formation changed here, is saved, and is durable from
session to session. However, the factory values can
be recovered by pressing the “Restore defaults” but-
ton. Note that operation of the Buck-Boost regulator
below 2.75V must be explicitly enabled.
4
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A
LTC3567EUF
QUICK START PROCEDURE
Complete the Quick Start Procedure outlined in the
Quick Start Guide for Demo Circuit 590 available
from the Linear Technology Web Site, prior to pro-
ceeding.
Using short twisted pair leads for any power connec-
tions, with all loads and power supplies off. Refer to
Figures 4 & 5 for the proper measurement and
equipment setup. Follow the procedure below:
NOTE.
When measuring the input or output voltage ripple, care must be taken to
avoid a long ground lead on the oscilloscope probe. Measure the input or output
voltage ripple by touching the probe tip directly across the VBUS or VOUT(x) and
GND terminals. See Figure 2 for proper scope probe technique.
< V(PROG) (VM5) < 1.0V. The USB current limit
is now 1A, so there is more than enough current
to operate the charger at 500mA.
5. Set PS1 to 0V, and Ld1 to 1A. Observe that 3.5V
< VOUT (VM2) <3.6V and V (VOUT, VBAT) <
200mV. The USB supply is off, and the only
source of energy is the battery. With VOUT
loaded at 1A, the ideal diode engages and energy
is routed from the battery to VOUT.
6. Set Ld1 to 400mA and PS1 to 5V. Observe that
3.8V < VOUT (VM2) < 4.0V. The USB current
limit is set to 1A, so both the charger load of
500mA, and 400mA into Ld1 can be supplied.
7. Set Ld1 to 0A, and use the GUI to enable
VOUT1. Observe that 3.8V < VOUT (VM2) <
4.0V and 3.25V < VOUT1 (VM4) < 3.35V. The
Buck-Boost regulator is now on, at no load.
The Buck-Boost regulator operates from VOUT.
8. Set Ld2 to 400mA. Observe 3.8V < VOUT
(VM2) < 4.0V, 3.25V < VOUT1 (VM4) < 3.35V.
The combined load of the charger and the load
on VOUT1, is still within the 1A current limit.
9. Use the GUI to turn off the battery charger, and
set Ld2 to 1A. Observe that 3.8V < VOUT (VM2)
< 4.0V, 3.25V < VOUT1 (VM4) < 4.0V. Because
the battery charger is off, the LTC3567 can sup-
ply 1A through the Buck-Boost regulator, and
stay within the 1A limit on USB current.
10. Set Ld2 to 0A, and use the GUI to turn on the
battery charger. Set NTC (JP3) to “EXT”. /CHRG
LED should flash.
11. Set NTC (JP3) to “INT” and EN1 (JP1) to “ON”.
Shut
off
all
supplies
and
loads.
1. Set EN1 (JP1) to “OFF” and /CHRGEN (JP4) to
“Lo”. Set PS1 to 5V, and PS2 to 3.6V. Start the
GUI using QuickEval.
2. Observe that 95mA < I (VBUS) (AM1) < 100mA,
3.6V < VOUT(VM2) < 3.7V, 1.15V < V(CLPROG)
(VM6) < 1.2V. The default state of the USB input
current limit is 100mA, so although the charger
is calling for 500mA, the USB input current is
limited to 100mA. Consequent to this, VOUT
drops until the charger only draws 100mA.
3. Use the GUI to set the USB input current limit to
5X (500mA). Observer that 460mA < I(VBUS)
(AM1) < 500mA, 3.8V < VOUT (VM2) < 4.0V,
and 0.95V < V(PROG) (VM5) < 1.0V. The USB
current limit is now 500mA, so the charger can
now deliver the full charge current. VOUT is now
approximately equal to V(BAT) + 0.3V, and
V(PROG) is a the servo voltage of 1.0V.
4. Use the GUI to set the USB input current limit to
10X (1A). Observe that 460mA < I(VBUS) (AM1)
< 500mA, 3.8V < VOUT (VM2) < 4.0V, and 0.95V
5
京公网安备 11010802033920号
EEWORLD
