Linear Technology Demo Circuit 1402A Quick Start Manual

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Demo Circuit 1402A

QUICK START GUIDE

Highly Integrated 6-Channel

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 PowerPath 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™ controller, 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.

LTC3577 and LTC3577-1

LTC3577 AND LTC3577-1

Portable PMIC

The LTC3577 has a high temperature battery voltage reduction feature that reduces the battery voltage under high temperature conditions to improve safety and reliability.

The high voltage (HV) buck interface is designed to connect 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.

PERFORMANCE SUMMARY

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Supply Range (V

Absolute Wall Input Threshold (VW) V

Operating Voltage 1.6 5.5

DVCC UVLO (V V

Regulated Output Voltage (V

BAT

Constant Current Mode Charge Current (I V

UVLO V

OUT

OUT1

OUT2

OUT3

LDO1 LDO2 Full-Scale LED Current 20 m

DVCC,UVLO)

) NOTE: The input current limit is reduced when VBUS falls

BUS

) LTC3577

FLOAT

CHRG

below 4.45V (TYP).

WALL

LTC3577-1

) R

PROG

OUT

0 to 500mA 3.3 0 to 500mA 1.8 0 to 800mA 1.2 0 to 150mA 1.5 0 to 150mA 2.5

Specifications are at TA = 25°C

4.35 5.5

Rising Falling

= 2KΩ, Input current limit = 1A 465 500 535 m Falling Rising

4.3

3.1

3.2

4.179

4.200

4.079

4.100

2.5 2.7

2.8 2.9

4.45

4.221

4.121

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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 Circuit 1402 utilizes the DC590B, USB to I2C 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 performance 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 technique.

Figure 2 for proper scope probe

1. Refer to the DC590B Quick Start Guide for QuikEvalTM

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.

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.

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.

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.

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.

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 efficiency to a slower rise time with better EMI performance.

13. Select the LDO1 and LDO2 EN/DIS buttons to enable

LDO1 and LDO2 via the I

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 vertical slider. The LED full scale current (I

LED(FS)

) for this

circuit is 20mA.

JP7.

VINLDO1 to “VOUT” position.

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LTC3577 AND LTC3577-1

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.

19. With the LED boost enabled, reduce the “PWM Nu-

merator” vertical slider while observing the LED intensity. Notice that the LEDs dim as the numerator is decreased.

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 appropriate 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 setting.

FSLED

CycleDuty =

Frequency =

)(IIFSLEDLED

)(

⎛

••

3^10

⎜ ⎝

8.0

500

•=

PWMNUM

PWMDE

PWMCLK

PWMDE

DAC

−

⎞ ⎟

⎠

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

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.

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 sequence up. VOUT POWER GOOD for each output is indicated on the STATUS section on the control window.

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 software 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 respectively. See Table 1 for details.

SHDN

feature such as the DC1394,

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LTC3577 AND LTC3577-1

Table 1. Input Current Limit Settings

ILIM1 ILIM0 CURRENT LIMIT

0 0 100mA (1X)

0 1 1A (10X)

1 0 0.5mA (SUSP)

1 1 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.

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LTC3577 AND LTC3577-1

Figure 1. Proper Measurement Equipment Setup

VIN

GND

Figure 2. Measuring Input or Output Ripple

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LTC3577 AND LTC3577-1

USING THE LTC3577 SOFTWARE

The LTC3577 program provides control of the mode and slew rate of the buck regulators, plus controls the intensity and slew rate of the LED boost controller. It also allows the user to view the contents of the status register. Refer to Figure 3 for an illustration of the LTC3577 control window.

VIEW LTC3577 PRODUCT PAGE

button opens an internet browser and searches the Linear Technology Corporation web site for information on the LTC3577 when an internet connection is available.

REG0

through

REG3

text box windows display the hexadecimal value that has been written to the corresponding registers.

STATUS REG

text box window displays the hexadecimal value that has been last read from the LTC3577 status register.

LDO1

and

LDO2 EN/DIS

buttons enable or disable LDO1

and LDO2 respectively via the I2C interface.

BUCK1

through

BUCK3 MODE

select buttons are used to individually set each buck regulator into Pulse Skip Mode for low noise or Burst Mode for high efficiency.

BUCK SW SLEW RATE

option buttons are used to choose one of four slew rates for optimal EMI reduction or efficiency. Choose “1ns” for optimal efficiency.

HV/SHDN HI/LOW

select button is used to turn on or shutdown the high voltage buck demo board with the shutdown feature.

When auto update is disabled, the LTC3577 I2C registers may be updated by selecting the “Update All Registers” button.

Update All Registers

button is used to update all of the

LTC3577 I2C write registers when selected.

NOTE:

When power is turned off or removed, the I2C registers are reset and the LTC3577 control window will not match the actual condition of the evaluation board. Use the “Update All Registers” button to set the device to the current settings selected on the LTC3577 control window.

LED EN/DIS

select button is used to enable or disable the

LED boost controller.

BOOST SW SLEW RATE FAST/SLOW

button is used to turn on and off the LED switch faster or slower for optimal efficiency or EMI reduction. Choose “FAST” for optimal efficiency.

LED MODE

option buttons are used to choose one of three Boost controller modes. CC Boost mode is a constant current mode where the LED current is controlled by the LED DAC REG vertical slider. HV Boost mode regulates the ILED pin to 0.8V to operate the Boost at a fixed voltage. HV Boost mode should not be enabled

unless the demo circuit has been modified to support this mode of operation. PWM mode allows the LED in-

tensity to be controlled by pulse width modulating the LEDs based on the LED DAC REG, PWM Numerator, PWM Denominator, and PWM Clock Speed settings.

NOTE:

When in CC Boost or HV Boost LED modes, the PWM controls

are disabled.

PWR_ON HI/LOW

select button is used to set the PWR_ON pin high or low to turn on or off VOUT1, VOUT2, and VOUT3.

AUTO READ BACK EN/DIS

select button is used to automatically update the status register every 250ms when enabled. When disabled the read register may be updated by selecting the “Read Back Status” button.

Read Back Status

button is used to update the status

AUTO UPDATE EN/DIS

cally update the LTC3577 I

select button is used to automati-

C registers when any of the

buck or LED buttons or sliders have been changed.

GRADATION TIME

option buttons set the desired time to gradate up to or down from the selected intensity whenever the LED controller is enabled or disabled.

LED DAC REG

vertical slider controls the LED current from 20uA to 20mA in 64 logarithmic steps. The intensity slider may be adjusted by clicking on the up or down arrows to increment or decrement by one LSB or by clicking and dragging the slide pointer. The hex code and LED current are displayed in the two text boxes below the slider.

PWM Clock Speed

option buttons are used to select the PWM clock speed. The PWM clock speed is divided by the PWM denominator to determine the PWM frequency.

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LTC3577 AND LTC3577-1

This can only be changed when the “PWM” “LED MODE” option button is selected.

PWM Numerator

numerator value. The PWM numerator is divided by the PWM denominator to determine the PWM duty cycle. This can only be changed when the “PWM” “LED MODE” option button is selected.

PWM Denominator

PWM denominator value. The PWM denominator is used

vertical slider is used to select a PWM

vertical slider is used to select a

in conjunction with the PWM numerator to determine the PWM duty cycle and with the PWM clock speed to determine the PWM frequency. This can only be changed when the “PWM” “LED MODE” option button is selected.

STATUS

status determined by the LTC3577 status register. If an acknowledge was not received, the status indicators will display “N/A”. This may occur when DVCC is missing or during the PDN state.

indicators display the charge, NTC, and power

Figure 3. LTC3577 Control Window

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