Linear Technology DC1937B Guide de configuration rapide

dc1937bf

DEMO MANUAL DC1937B

DESCRIPTION

LTC3350EUHF

High Current Supercapacitor Backup

Controller and System Monitor

Demonstration circuit 1937B is a supercapacitor charger

and backup controller with supercapacitor health and

system monitoring; featuring the LT C

3350. The LTC3350

hasabucksupercapacitor charger, backup boost controller

and an input ideal diode to disconnect the input supply

in backup mode. An output ideal diode allows the super-

capacitors to supply the output when VCAP is above the

set backup voltage. As the capacitor stack voltage drops

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

QuikEval is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

PERFORMANCE SUMMARY

down to the set output voltage, the LTC3350 will operate

as a boost regulator to supply the output until the energy

in the supercapacitors are depleted.

Design files for this circuit board are available at

http://www.linear.com/demo/DC1937B

Specifications are at TA= 25°C

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Supply Range 10.8 12 20 V

Input Current Limit 2 A

VOUT Backup Operating Voltage Boost Mode 6 V

VCAP Float Voltage Buck Mode 10 V

Max Charge Current 5.33 A

tBACKUP PBACKUP = 25W, IBOOST = 9.67A, 3 ≤ VCAP ≤ 10 3.2 s

BOARD PHOTO

dc1937bf

DEMO MANUAL DC1937B

QUICK START PROCEDURE

ObtainandconnectaDC590BboardtotheDC1937Bboard.

Using short twisted pair leads for the power connections

and with the LOAD and the power supply OFF. Refer to

Figure 1 and Figure 2 for the proper measurement and

equipment setup. Follow the procedure below.

1. Refer to the DC590B Quick Start Guide for QuikEval™

setup and software installation details.

2. Make sure the USB cable is connected between the

computer and the DC590B controller board.

3. Connect a 14-pin ribbon cable from the DC590B board

to the DC1937B board.

4. Set the VCCIO jumper, JP6, on the DC590B board to

the 5V position.

5. Set the JP1 jumper on the DC1937B board to the

DC590 position.

6. Start the Linear Technology QuikEval program. This

program should automatically detect the presence of

the LTC3350 demo board (DC1937B) and activate the

appropriate GUI, as seen in Figure 5.

TYPICAL APPLICATION

High Current Supercapacitor Charger and Backup Supply

Backup Operation

PFI OUTFB

OUTFET

TGATE

BGATE

ICAP

VCAP

CAP4

CAP3

CAP2

CAP1

CAPRTN

CAPFB

INFET VOUTSP VOUTSN

CHG

(STEP-DOWN) I

BACKUP

VCAP < VOUT

(STEP-UP)

VCAP > V

OUT

(DIRECT

CONNECT)

OUT

LTC3350

10F

VCAP

10F

dc1937b TA01a

I2C

VIN

2V/DIV

VCAP

2V/DIV

VOUT

2V/DIV

400ms/DIV

BACK PAGE APPLICATION CIRCUIT

dc1937b TA01b

PBACKUP = 25W

VOUT

VCAP

VIN

7. With power off, connect a 0V to 20V, 25W supply

between the VIN and GND terminals with a series

ammeter and a voltmeter as shown in Figure 1.

8. Turn on and set the VIN input power supply to 12V and

observe the CAP voltages, input and charge current

on the GUI.

NOTE. Make sure that the input voltage does not

exceed 20V.

NOTE. The LTC3350 is intended to operate with a low

impedance source. If operating near the PFI rising

threshold, make sure the input voltage does not drop

more than 30mV • (R5 + R6)/R6, 266mV, during a

charge event.

9. On the LTC3350 Control Window, click on the CAP

and ESR Measurement START button. An In Process

indicator displays whilethe measurement is in process.

NOTE. Supercapacitors initially have large leakage

currents which causes the capacitance measurement

to be low. The capacitor measurements will be more

accurate after the 10F capacitors have been continu-

ously charged for more than 30 minutes.

dc1937bf

DEMO MANUAL DC1937B

10. Connecta0Wto25Wconstantpowerloadboxbetween

VOUT and GND and set to 25W.

11. Connect an oscilloscope probe each to VIN, VOUT,

VCAP and PFO. Set the oscilloscope to trigger on the

falling edge of PFO.

12. Remove the input power and observe how the output

drops to the regulation point and is maintained until

the energy in the supercapacitors are exhausted.

QUICK START PROCEDURE

13. The LTC3350 has the ability to monitor and report on

the supercapacitor and system voltages, currents, die

temperature and capacitor health. See the software

section and data sheet for more information.

14. The DC1937B can be modified to operate at differ-

ent frequencies, operating voltages, input and boost

currents. The Hardware Config tab allows the user to

enter the appropriate changes so the GUI can report

the correct measurements. See the Software section

for more details.

Figure 1. Proper Measurement Equipment Setup

Figure 2. Measuring Input or Output Ripple

dc1937bf

DEMO MANUAL DC1937B

APPLICATION INFORMATION

Figure 3. Charger Efficiency Figure 4. Boost Efficiency

VCAP (V)

EFFICIENCY (%)

100

05 93 7

dc1937b F03

4 82 61

IOUT (A)

EFFICIENCY (%)

100

01.5 3.50.5 2.5

dc1937b F04

4.0

1.0 3.02.0

VCAP = 5V

VCAP = 4V

VCAP = 3V

The DC1937B was designed to provide 25W of power for

a total of 1.8 seconds with a backup voltage of 6V. It was

also determined that the maximum life expectancy of this

product is six years with a maximum ambient tempera-

ture of 45°C. When choosing the capacitance needed the

condition of the supercapacitor at end of life (EOL) needs

to be considered. EOL is typically when the capacitance

decreases by 30% and when the ESR doubles. With this

knowledge and a few calculations the capacitors needed

for this application can be chosen. Refer to the LTC3350

data sheet for more details on the formulas used in the

following examples.

Since the backup time and backup power are known, the

next item that needs to be determined is the maximum

voltage to be applied to the capacitor VCELL(MAX) to provide

the maximum life expectancy for the application. Refer to

the capacitor manufacture’s data sheet for this informa-

tion. A VCELL(MAX) of 2.5V was chosen for the 6 year life

expectancy of this product.

The number of capacitors in the stack also needs to be

chosen plus the Utilization Factor (αB). αBis the amount

of energy in the capacitor to be used for backup. A typi-

cal αBis 80%, but a conservative αBof 70% was used

on the DC1937B. The minimum capacitance required for

each capacitor in the stack at EOL can be calculated by

the following equation:

CEOL ≥

BACKUP

• t

BACKUP

nηVCELL(MAX)2•

αB+ αB– 1– αB

( )

ln 1+ αB

1– αB

























–

Where ηrepresents the boost efficiency, n represents the

number of capacitors in the stack. Based on an efficiency

of 90% and the backup requirements, the minimum CEOL

is calculated as:

CEOL ≥

4•25W •1.8s

4• 0.9 •(2.5V)2•

0.7+0.7 – 1– 0.7

( )

ln 1+0.7

1– 0.7

























–1

=6.816F

The maximum capacitor ESR at end of life can then be

determined below:

ESREOL ≤η(1– αB)nV2(CELL(MAX)

4PBACKUP

dc1937bf

DEMO MANUAL DC1937B

The capacitor ESREOL is determined below:

ESREOL ≤0.9(1– 0.7)• 4 •(2.5V)2

4•25W

=67.5mΩ

Now the EOL parameters are known, the capacitor can be

chosenbasedon the manufacture’scapacitorspecification

for EOL. For the DC1937B, the NESSCAP ESHSR-0010C0-

002R7 was chosen with a CEOL of 7F, an ESREOL of 64mΩ

and a maximum current of 10.1A.

To verifythe capacitors are adequate at EOL we first need to

determine the minimum stack voltage (VSTK(MIN)) at EOL.

VSTK(MIN) will be limited by either the maximum power

transfer rule or by current limit, whichever is greater. The

minimum capacitor voltage due to the maximum power

transfer rule can be calculated with the following formula:

VSTK(MIN) =4•ESREOL •n•PBACKUP

VSTK(MIN) is the maximum stack voltage (n• VCELL). The

desired VSTK(MIN) due to the maximum power transfer

rule is calculated as:

4• 4 •64mΩ•25W

0.9 =5.333V

VSTK(MIN) can also be determined by the current limit and

the ESREOL as shown in the following equation:

VSTK(MIN) =

BACKUP

ηI

LMAX

+nESREOLILMAX

Where ILMAX is the boost peak current limit. The EOL

VSTK(MIN) based on boost peak current limit is calculated

below:

25W

0.9 •9.67A

+4•64mΩ•9.67A =5.348V

Now VSTK(MIN) at EOL is known, the VSTK(MIN) can be

rearranged to calculate actual αBat EOL. The calculated

VSTK(MIN) can also be used to determine if the chosen

capacitor will be sufficient for worst case EOL conditions,

when both ESREOL and CEOL have been reached.

tBACKUP =

ηC

STK

BACKUP

•

γ(MAX)V2(STK(MAX) –γ(MIN)V2(STK(MIN) – V2LOSS







Where CSTK is the total stack capacitance, VSTK(MIN) is

based on the higher calculated VSTK(MIN),

γ(MAX) =1+1– 4nESREOL •PBACKUP

ηV2STK(MAX)

γ(MIN) =1+1– 4nESREOL •PBACKUP

V2STK(MIN)

and

V2LOSS =4nESREOLP

BACKUP

ηln γ(MAX)VSTK(MAX)

γ(MIN)VSTK(MIN)













The worst case EOL backup time is calculated below:

γ(MAX) =1+1– 4 • 4• 64mΩ•25W

0.9 •(10V)2=1.8459

γ(MIN) =1+1– 4• 4 •64mΩ•25W

0.9 •(5.348V)2=1.0740

VLOSS2=

4• 4 •64mΩ•25W

0.9 •

ln 1.8459 •10V

1.0740 •5.348V









=33.207V2

tBACKUP =

0.9 •









F

4•25W •

1.846 •(10V)2–1.074•(5.348V)2– 33.207V2





=1.9s

The above results show that if both ESREOL and CEOL are

reached then the backup requirement will be met. If the

backup requirement was not met, then a capacitor with

lower ESR and/or more capacitance should be chosen.

APPLICATION INFORMATION

dc1937bf

DEMO MANUAL DC1937B

USING THE LTC3350 SOFTWARE

The LTC3350 program provides the ability to measure

and monitor the system voltages and currents plus the

health of the supercapacitors. It also allows the user to

set up alarms to report on specific events such as power

fail or cap measurement done. Refer to Figure 5 for an

illustration of the LTC3350 control window.

VIEW LTC3350 PRODUCT PAGE button opens an Internet

browser and searches the Linear Technology Corporation

website for information on the LTC3350 when an Internet

connection is available.

CAP and ESR Measurement START button starts a ca-

pacitor and ESR measurement. An indicator below the

START button indicates the status of the capacitor/ESR

measurement. The different states are; In Process, Done,

Pending or Failed.

Number of Caps Selected text box indicates the number

of capacitors selected using the CAP_SLCTx pins.

SMBALERT Detected indicator indicates if an SMBALERT

has been detected or not.

Clear SMBUS ALERT button sends an SMBus alert re-

sponse address to clear the SMBALERT. Note, the condi-

tion that caused the SMBALERT must be cleared before

the SMBALERT signal can be cleared.

CAP text box indicates the latest measured capacitance in

Farads for large capacitors and mF for smaller capacitors.

This measurement is based on the CAP scale setting in the

control register plus the Current and Oscillator Resistor

Settings on the Hardware Config tab.

ESR text box indicates the latest measured ESR in mΩ.

VCAP text box indicates the latest VCAP voltage in Volts.

ICHRG text box indicates the latest measured charge/

boost current in amps. This measurement is based on the

RSNSC setting on the Hardware Config tab.

VCAPx text box indicates the latest measured capacitor

voltage in Volts for the corresponding VCAP.

VIN text box indicates the latest measured input voltage

in Volts.

IIN text box indicates the latest measured input current in

amps. This measurement is based on the RSNSI setting

on the Hardware Config tab.

VOUT textbox indicates the latest measured VOUT in Volts.

GPImon

text box indicates the latest measured GPI voltage

in Volts. An internal buffer can be enabled for measuring

high impedance inputs.

Die Temp text box displays the latest internally measured

die temperature in °C.

in hexadecimal format.

Read Values button causes the LTC3350 to read all of the

ADC measured values. This is useful when the LTC3350

GUI “Auto Update” is disabled.

Auto Update Enable/Disable button causes the LTC3350

to read all of the LTC3350 registers periodically and writes

to any register changed when enabled. The Read Values,

Read All, or Update All buttons can be used instead to

update the registers when in the disabled state.

Read All button causes the LTC3350 to read all of the

LTC3350 registers. This is useful when the LTC3350 GUI

Auto Update is disabled.

CHARGER CONTROL TAB

The Charger Control tab contains the indicators and con-

trols for the capacitor charger and monitor plus the GPI

buffer enable as shown in Figure 5.

ChargerStatusSTATUSBitsindicateswhentheassociated

chrg_status register bits are set. See the data sheet from

more information on these bits.

Charger Status Read text box displays the last read

chrg_status register value in hexadecimal format.

CAP ESR Period text box allows the user to set a period

in which the LTC3350 will perform a capacitance and

ESR measurement. The text box is formatted in hours,

minutes, and seconds. The LSB for the CAP ESR Period

CAP ESR Period Write text box displays the value that

will be or has been written to the cap_esr_period register

value in hexadecimal format.

CAP ESR Period Read text box displays the last value read

from the cap_esr_period register in hexadecimal format.

dc1937bf

DEMO MANUAL DC1937B

USING THE LTC3350 SOFTWARE

Figure 5. LTC3350 Control Window

VCAP FB text box allows the user to set the CAPFB refer-

ence voltage from 0.6375V to 1.2V in 37.5mV increments.

The value in the text box is rounded to the nearest mV. The

VCAP text box is also updated with the calculated value

of the CAPFB reverence voltage and the resistor network

entered on the Hardware Config tab.

VCAP FB Write text box displays the value that will be or has

beenwrittentothevcapfb_dacregisterinhexadecimalformat.

VCAP FB Read text box displays the last value read from

the vcapfb_dac register in hexadecimal format.

VCAP text box allows the user to set the VCAP float volt-

age within the limits of the CAPFB reference voltage and

the CAPFB resistor network on the Hardware Config tab.

The value in the text box is rounded to the nearest mV.

The VCAP FB text box is also updated with the calculated

value using the CAPFB resistor network entered on the

Hardware Config tab.

VSHUNT text box allows the user to set the shunt regulator

voltage up to 3.6V or disable the shunt regulator. The shunt

voltage will be reset to the default value of 2.7057 every

time INTVCC is restored. Set VSHUNT to 0V to disable the

shunt regulator.

VSHUNTWritetextboxdisplaysthe value that will be or has

been written to the vshunt register in hexadecimal format.

VSHUNT Read text box displays the last value read from

the vshunt register in hexadecimal format.

Stop CAP Measurement sets the ctl_stop_capesr bit in

the ctl_reg register. This will cause any CAP/ESR mea-

surement in process to stop. This bit will reset when the

measurement has ceased.

CAP SCALE button sets the cap scale from large scale,

default scale for larger capacitors, to small scale for

smaller capacitors. The resolution is increased by 100x

in small scale.

GPI BUFFER ENABLE button sets the ctl_gpi_buffer_en

bit when enabling the GPI input buffer. When the GPI

BUFFER ENABLE is off then the GPI input is measured

without the input buffer.

Control Reg Write text box displays the value that will be

or has been written to the ctl_reg register in hexadecimal

format.

Control Reg Read text box displays the last value read

from the ctl_reg register in hexadecimal format.

dc1937bf

DEMO MANUAL DC1937B

Figure 6. Monitor Status/Alarms Tab

MONITOR STATUS/ALARMS TAB

The Monitor Status/Alarms tab contains the indicators for

the mon_status and alarm_reg bits plus control buttons

for the Monitor Status Mask, Alarm Mask and Alarm Clear

bits as shown in Figure 6.

Monitor Status STATUS Bits indicate when the associated

mon_status register bits are set. See the data sheet from

more information on these bits.

Monitor Status Read text box displays the last read

mon_status register value in hexadecimal format.

Mask Monitor Status buttons will allow the rising edge of

the associated monitor status bit to trigger the SMBALERT

when the mask bit is set to 1.

Mask Mointor Write text box displays the value that will

be or has been written to the msk_mon_status register

in hexadecimal format.

Mask Monitor Read text box displays the last read

msk_mon_status register value in hexadecimal format.

Alarm Bits indicatewhen the associated alarm_regregister

bits are set. See the data sheet from more information on

these bits.

Alarm Read text box displays the last read alarm_reg

Mask Alarm buttons will allow the associated alarm bit

to trigger the SMBALERT when the mask bit is set to 1.

Mask Alarm Write text box displays the value that will

be or has been written to the msk_alarms register in

hexadecimal format.

Mask Alarm Read text box displays the last read msk_

alarms register value in hexadecimal format.

Clear Alarm buttons will cause the associated alarm to

clear when the alarm condition no longer exists. The Clear

alarm bit will reset low when the alarm is cleared.

Clear Alarm Write text box displays the value that will

be or has been written to the msk_alarms register in

hexadecimal format.

Clear Alarm Read text box displays the last read msk_

alarms register value in hexadecimal format.

USING THE LTC3350 SOFTWARE

dc1937bf

DEMO MANUAL DC1937B

SET ALARMS TAB

The Set Alarms tab contains text boxes to allow the user

to set specific levels for each alarm register as shown in

Figure 7. Each alarm has an associated Write text box to

display the value that will be or has been written to the

associatedregister in hexadecimal format. Each alarm also

hasanassociatedReadtext box which displays the last read

contents of the associated register in hexadecimal format.

VIN/VOUT/VCAP/CAP/GPI UV alarm text boxes allow the

user to enter a voltage that will trigger an alarm when the

associated voltage drops below the entered voltage value

and the associated alarm mask bit is set.

VIN/VOUT/VCAP/CAP/GPI OV alarm text boxes allow the

user to enter a voltage that will trigger an alarm when the

associated voltage rises above the entered voltage value

and the associated alarm mask bit is set.

IIN OC alarm text boxes allow the user to enter a current

or the voltage across the sense resistor that will trigger an

alarm when the input current increase above the entered

value and the msk_iin_oc alarm mask bit is set.

USING THE LTC3350 SOFTWARE

Figure 7. Set Alarms Tab

CAPLOalarm text box allows the user to enteracapacitance

based on the current ctl_cap_scale setting in the ctl_reg. A

CAP LO alarm will be triggeredif the measured capacitance

islower than the enteredvalueandthe msk_cap_lobit is set.

ESR HI alarm text box allows the user to enter an ESR

value based on the RSNSC resistor value entered in the

Hardware Config tab. An ESR HI alarm will be triggered

if the measured ESR is higher than the entered value and

the msk_esr_hi bit is set.

ICHRG UC alarm text boxes allow the user to enter acurrent

or the voltage across the sense resistor that will trigger

an alarm when the charge current decreases below the

entered value and the msk_ichrg_lo bit is set.

Die Temp Cold alarm text box allows the user to enter a

die temperature in °C that will trigger an alarm when the

temperature decreases below the entered value and the

msk_dtemp_cold bit is set.

Die Temp Hot alarm text box allows the user to enter a

die temperature in °C that will trigger an alarm when the

temperature increases above the entered value and the

msk_dtemp_hot bit is set.

dc1937bf

DEMO MANUAL DC1937B

Figure 8. Hardware Config Tab

Apply button writes to all of the alarm registers and reads

the values back from the LTC3350.

Cancel button changes all the entered values that have

not yet been written to the LTC3350 back to their previ-

ous values.

Restore Defaults button changes all of the LTC3350 alarm

registers back to the default values determined from the

GUI. This does not set the alarm to the LTC3350’s default

settings of 0x0000.

HARDWARE CONFIG TAB

The Hardware Config tab, shown in Figure 8, contains text

boxes to allow the user to enter the values to configure

the necessary resistors to match the configuration of the

demo board. These values are used by the GUI to calculate

measured CAP and ESR values, display input/charge cur-

rents and max VCAP voltage for a given reference setting,

and also used in the Set Alarm tab text boxes.

VPFI Resistor Settings text boxes allow the user to enter

thePFIresistordivider network in kΩ.Thecalculated falling

PFI threshold set point is displayed in Volts.

VOUT Resistor Settings text boxes allow the user to enter

the VOUT resistor divider network in kΩ. The calculated

VOUT backup set point is displayed in Volts.

RITST text box allows the user to enter the RITST resistor

in Ω. The calculated test current setting is displayed in mA.

REXT text box allows the user to enter the external load

resistance, R28 and R29, added in Ω if any. Enter –1 if

thereis not any external loading and OPEN will be displayed

in the text box. See the Using Large Capacitor section for

more details.

RT text box allows the user to enter the RT resistor in kΩ.

The calculated oscillator setting is displayed in kHz.

Total RBalance text box allows the user to enter the

equivalent total balance resistance in Ω if any for ca-

pacitancestacks or packs that have external balancing.

Enter–1 if there is not any external balancing and OPEN

will be displayed in the text box.

RSNSI text box allows the user to enter the RSNSI resis-

tor in mΩ. The calculated input current limit setting is

displayed in Amps.

RSNSCtextboxallowstheusertoentertheRSNSCresistor

in mΩ. The calculated maximum charge current setting

is displayed in Amps.

VCAP Resistor Settings text boxes allow the user to enter

the CAPFB resistor divider network in kΩ. The calculated

maximum VCAP set point is displayed in Volts.

CAP1 Voltage Divider text boxes allow the user to enter

the CAP1 resistor divider network in kΩ if used. This is

primarily used for the Zeta/SEPIC application (Data sheet

Application Circuit 6). The displayed CAP1 voltage is

calculated from the maximum VCAP voltage. Enter –1 in

the CAP1 Voltage Divider RTop and RBot text boxes then

OPEN will be displayed in both text boxes.

USING THE LTC3350 SOFTWARE

Ce manuel convient aux modèles suivants

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