Demo Circuit 1402A
QUICK START GUIDE
LTC3577
AND
LTC3577-1
LTC3577
and
LTC3577-1
Highly Integrated 6-Channel
Portable PMIC
The LTC3577 has a high temperature battery voltage re-
duction feature that reduces the battery voltage under
high temperature conditions to improve safety and reli-
ability.
The high voltage (HV) buck interface is designed to con-
nect to and control an external HV buck regulator demo
board via the Bat-Track control circuitry. Some of these
demo boards are the DC1394A, DC1395A, and DC1325A,
featuring the LT3480, LT3505, and the LT3563 HV bucks
respectively.
Refer to the LTC3577 datasheet for more details on the
electrical and timing specifications.
Design files for this circuit board are available. Call
the LTC factory.
L
, LTC, LTM, LT are registered trademarks of Linear Technology Corporation. PowerPath
and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
DESCRIPTION
WARNING!
Do not look directly at operating LED.
This circuit produces light that can damage eyes.
Demo Circuit 1402 is a Highly Integrated 6-Channel
Portable PMIC with a push button controller, two LDOs,
three buck converters, a Li-Ion battery charger, a Power-
Path controller, and high voltage buck controller interface
featuring the LTC3577 and LTC3577-1.
The LTC3577 is a PowerPath™ manager with automatic
load prioritization, battery charger, Bat-Track™ control-
ler, push button controlled power up sequence and reset,
and a 10 LED string controller with gradation and PWM
control. The three buck regulators and the LED Boost
controller have adjustable slew rates for EMI reduction.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
PARAMETER
Input Supply Range (V
BUS
)
Absolute Wall Input Threshold (V
W
)
DV
CC
Operating Voltage
DV
CC
UVLO (V
DVCC,UVLO)
V
BAT
Regulated Output Voltage (V
FLOAT
)
Constant Current Mode Charge Current (I
CHRG
)
V
OUT
UVLO
V
OUT1
V
OUT2
V
OUT3
LDO1
LDO2
Full-Scale LED Current
CONDITIONS
NOTE: The input current limit is reduced when VBUS falls
below 4.45V (TYP).
V
WALL
Rising
V
WALL
Falling
MIN
4.35
TYP
MAX
5.5
4.45
5.5
1
4.200
4.100
500
2.7
2.8
3.3
1.8
1.2
1.5
2.5
20
4.221
4.121
535
2.9
UNITS
V
V
V
V
V
V
V
mA
V
V
V
V
V
V
V
mA
4.3
3.2
3.1
1.6
4.179
4.079
465
2.5
LTC3577
LTC3577-1
R
PROG
= 2KΩ, Input current limit = 1A
V
OUT
Falling
V
OUT
Rising
0 to 500mA
0 to 500mA
0 to 800mA
0 to 150mA
0 to 150mA
1
LTC3577 AND LTC3577-1
QUICK START PROCEDURE
Demo Circuit 1402 is designed to be used with a USB
input and/or an external HV buck demo board, such as
the DC1325A, DC1394A, or DC1395A featuring the
LT3653, LT3480 and the LT3505 respectively. Demo Cir-
cuit 1402 utilizes the DC590B, USB to I
2
C interface
board, to control the LED boost driver, LDO enables, and
buck modes. It is also used to monitor the buck and LDO
outputs, plus battery charger status. This circuit may be
evaluated using a lithium ion battery or a battery simula-
tor consisting of a 0V-5V, 3A power supply and a
3.6Ω power resistor.
The DC1402 is easy to set up to evaluate the perform-
ance of the LTC3577 and LTC3577-1. Refer to Figure 1
and Figure 2 for proper measurement equipment setup
and follow the procedure below to evaluate using the
DC590B board:
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 Vin or Vout and GND terminals. See Figure 2 for proper scope probe
technique.
5.
Connect DC1402 to the DC590B USB Serial Controller
using the supplied 14-conductor ribbon cable as
shown in Figure 1.
6.
With power off, connect a 5V, 1A power supply to
VUSB and GND with a series ammeter and a voltmeter
as shown in Figure 1.
7.
Connect a battery or a battery simulator set to 3.6V
between BAT and GND with a series ammeter and a
voltmeter as shown in Figure 1.
8.
Turn on and set the VUSB input power supply to 5V.
The DC590B board gets its power from the USB cable.
NOTE.
Make sure that the input voltage does not exceed 6V.
9.
Run the QuikEval.exe program. The LTC3577 control
window (shown in Figure 3) pops up.
NOTE.
The Status indicators on the software control window may display
“N/A” when an I2C ACK was not received. This occurs when the part is in
the power down (PDN) state or when DVCC is missing. Please refer to
the LTC3577 datasheet for more information on the PDN state.
1.
Refer to the DC590B Quick Start Guide for QuikEval
TM
setup and software installation details.
2.
Set the VCCIO jumper, JP6, on the DC590B board to
the 3.3V position.
NOTE.
The DVCC voltage level may be selected on the DC590B. This is
done by setting the VCCIO jumper, JP6, on the DC590B board to one of
the following settings: 3.3V, 5V, removed for 2.7V or set to external if an
external supply is desired to be used.
10.
On the LTC3577 control window, select the PWR_ON
HI/LOW button. When “HI” is indicated on the button,
the PWR_ON pin goes high and the VOUT1, VOUT2,
and VOUT3 outputs sequence up. VOUT POWER
GOOD for each output is indicated on the STATUS
section on the control window.
11.
Select the BUCK1 through BUCK3 MODE buttons to
switch the bucks into Burst mode. Observe the output
ripple and the quiescent current before and after
switching modes.
12.
Select the desired BUCK SW SLEW RATE option but-
ton to switch between a fast rise-time for best effi-
ciency to a slower rise time with better EMI perform-
ance.
13.
Select the LDO1 and LDO2 EN/DIS buttons to enable
LDO1 and LDO2 via the I
2
C bus.
14.
Set the LED DAC REG vertical slider to a desired cur-
rent level. The LED current and the LED DAC register
setting are displayed in the test boxes below the verti-
cal slider. The LED full scale current (I
LED(FS)
) for this
circuit is 20mA.
3.
Make sure the USB cable is connected between the
computer and the DC590B controller board.
4.
Set the jumpers on the DC1402-2 board to the follow-
ing settings:
JP1.
PWR_ON CNTL to “SW” position.
JP2.
ILIM1 to “1” position.
JP3.
ILIM0 to “1” position.
JP4.
STATUS PIN PULL-UP to “VOUT” position.
JP5.
NTC to “INT” position.
JP6.
VINLDO2 to “VOUT” position.
JP7.
VINLDO1 to “VOUT” position.
2
LTC3577 AND LTC3577-1
I
LED
=
DAC
−
63
⎞
⎛
•
10 ^
⎜
3
•
⎟
I
LED
(
FS
)
63
⎝
⎠
I
LED
(
FS
)
=
0.8
V
•
500
R
18
23.
With power off, connect a power supply to the input
of the HV buck circuit. Turn on the power supply and
set the voltage within the HV buck input operating
range.
NOTE.
If HV BUCK demo board has a
SHDN
feature such as the DC1394,
LT3480 demo board, select the “HV/SHDN HI/LOW” button on the
LTC3577 Control Window to put the HV BUCK into and out of shutdown.
15.
Select the LED EN/DIS button to turn on the LEDs.
Select the button again to turn off the LEDs.
16.
Select the “460ms” GRADATION TIME option button
then select the LED EN/DIS button. Observe how the
LEDs turn on and off smoothly when the LED boost
circuit is enabled and disabled.
17.
Select the “PWM” LED MODE option button. This
allows the LED intensity to be adjusted with the PWM
controls as well as the DAC register.
18.
Set the “PWM Numerator” and the “PWM Denomi-
nator” vertical sliders to their maximum position. The
hexadecimal value of “F” is displayed in the setting
text boxes below the sliders. The PWM duty cycle and
frequency are also displayed below the setting text
boxes.
PWMNUM
Duty Cycle
=
PWMDEN
Frequency
=
PWMCLK
PWMDEN
24.
Observe that the input current is now coming from
the HV buck input instead of the VUSB input and
VOUT is about VBAT plus 0.3V.
25.
Increase VBAT to 4.0V and observe how VOUT and
the HV BUCK output tracks the battery voltage.
26.
Refer to the “USING THE LTC3577 SOFTWARE” sec-
tion for more information on how to control the device
using the LTC3577 control window.
27.
Set the “PWR_ON CNTL” jumper, JP1, to the “PB”
position to power up/down the device with the “ON”
pushbutton, PB1.
28.
Depress the “ON” pushbutton, PB1 (minimum of
400ms). VOUT1, VOUT2, and VOUT3 outputs se-
quence up. VOUT POWER GOOD for each output is
indicated on the STATUS section on the control win-
dow.
29.
Wait at least five seconds from depressing PB1, then
depress the “PWR_ON” pushbutton, PB2. VOUT1,
VOUT2, and VOUT3 outputs shutdown.
30.
Again depress PB1, the “ON” pushbutton. VOUT1,
VOUT2, and VOUT3 outputs sequence up.
31.
Wait at least five seconds from depressing PB1, and
then depress and hold PB1 for at least 5 seconds. The
device enters the power down (PDN) state, VOUT1,
VOUT2, and VOUT3 outputs shut down and the soft-
ware control window STATUS indicators display
“N/A”.
32.
To return from the PDN state, depress PB1 again or
change JP1 to the “SW” position and set the
“PWR_ON HI/LOW” button on the software control
window to “HI”.
33.
The input current limit may be adjusted by changing
the “ILIM0” and “ILIM1” jumpers, JP3 and JP2 re-
spectively. See Table 1 for details.
19.
With the LED boost enabled, reduce the “PWM Nu-
merator” vertical slider while observing the LED inten-
sity. Notice that the LEDs dim as the numerator is de-
creased.
20.
Select a different “PWM Clock Speed” option button
and observe the PWM frequency changes accordingly.
21.
If using an external HV buck demo board, connect it
to demo circuit 1402-2 as indicated in Figure 1.
22.
Refer to the appropriate HV buck Quick Start Guide
to set the HV buck demo board jumpers to the appro-
priate settings. If using the DC1325A, LT3653EDCB
HV buck demo board, set the “WALL” jumper, JP1, to
the “HV BUCK” position. Then set jumpers JP2 and
JP3 to the “1” position to obtain a 1.2A current set-
ting.
3
LTC3577 AND LTC3577-1
Table 1. Input Current Limit Settings
ILIM1
0
0
1
1
ILIM0
0
1
0
1
CURRENT LIMIT
100mA (1X)
1A (10X)
0.5mA (SUSP)
500mA (5X)
34.
Refer to the LTC3577 datasheet for more details on
how the LTC3577 operates.
35.
When done, turn off all loads and power supplies,
then close the LTC3577 control window.
4
LTC3577 AND LTC3577-1
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
VIN
GND
5
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