DC1688A Datasheet DC1688A | P1-P3

dc1688afa

DEMO MANUAL DC1688A

DESCRIPTION

LT3652HVEDD

17.7V to 34V Input SLA 2A

Battery Charger For Solar Power

Demonstration circuit 1688A is a sealed-lead acid 2A

battery charger for solar power applications featuring the

LT3652HVEDD. The LT3652HV is a complete mid-power

battery charger that can operate over a wide input volt-

age range. The charger employs a 3.3V battery voltage

feedback reference that allows the voltage for charging to

be adjusted up to 18V. The LT3652HV has an input voltage

regulation loop which reduces charge current if the input

falls below a programmed level, set with a resistor divider.

The circuit provides constant-current/constant-voltage

charging with a maximum charge current of 2A that is

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

Technology Corporation. All other trademarks are the property of their respective owners.

Table 1. Typical Speciﬁ cations (T

= 25°C)

PARAMETER CONDITIONS VALUE

Input Voltage Range 17.7V to 34V

BAT

Charge/V

BAT

Float 14.3V to 14.5V/13.4V to 13.6V

Output Charge/Float Voltage Constant Voltage Mode 14.4V/13.5V

Output Current Limit I

LIM

IN_REG

Greater Than 2.7V 2A

PERFORMANCE SUMMARY

programmed by a current sense resistor. A precondition

feature trickle charges a low voltage battery, and bad

battery detection provides a signal if the battery doesn’t

respond to preconditioning.

The LT3652HVEDD is available in a 12-lead (3mm × 3mm)

DFN surface mount package with an exposed pad.

Design ﬁ les for this circuit board are available at

http://www.linear.com/demo

OPERATING PRINCIPLE

LT3652HV is a complete monolithic mid-power battery

charger, addressing high input voltage applications with

solutions that require a minimum number of external

components. The IC uses a 1MHz constant frequency,

average current mode step-down architecture.

The LT3652HV maximizes efﬁ ciency during charging cycles

by using a bootstrapped supply to drive the internal power

switch. Figures 1 and 2 display charger efﬁ ciency and input

current for various input voltages and battery voltages. A

precision threshold shutdown pin allows the incorporation

of UVLO functionality using a simple resistor divider. The

IC can also be put into a low-current shutdown mode, in

which the input supply bias is reduced to only 15μA.

The LT3652HV incorporates several degrees of charge cur-

rent control freedom. The overall maximum charge current

is set using an external inductor current sense resistor. The

LT3652HV employs an input voltage regulation loop which

reduces charge current if the input voltage falls below a

programmed level, set with a voltage divider. This can be

seen in Figure 3. When the LT3652HV is powered by a

solar panel, the input regulation loop is used to maintain

the panel at peak output power.

The LT3652HV automatically enters a battery precondi-

tion mode if the sensed battery voltage is very low. In

this mode, the charging current is reduced to 15% of

the programmed maximum, as set by the inductor sense

dc1688afa

DEMO MANUAL DC1688A

QUICK START PROCEDURE

Demonstration circuit 1688A is easy to set up to evaluate

the performance of the LT3652HVEDD.

resistor, R

SENSE

. Once the battery voltage increases to

the precondition threshold, the IC automatically increases

maximum charging current to the full programmed value.

DC1688A programs the output voltage to be 14.4V during

charging and the 9.5V precondition threshold is internally

set as a fraction of the programmed output voltage.

The LT3652HV can use a charge current based ‘C/10’

termination scheme, which ends a charge cycle when the

battery charge current falls to 1/10th the programmed

maximum charge current. The LT3652HV also contains

an internal charge cycle control timer, for timer-based

termination. When using the internal timer, the IC com-

bines C/10 detection with a programmable time constraint,

during which the charging cycle can continue beyond the

C/10 level. DC1688A programs a lower 13.5V ﬂ oat output

voltage at the time the C/10 condition occurs. Use of the

internal timer allows DC1688A to provide a ﬂ oat voltage

to the battery until the charge cycle terminates because

time elapses. The timer on DC1688A is programmed so the

circuit can provide a ﬂ oat voltage all day, as may be needed

by a solar panel application. When the timer-based scheme

is used, the IC also supports “bad battery” detection, which

triggers a system fault if a battery stays in precondition

mode for more than 1/8th of the total charge cycle time.

Once charging is terminated and the LT3652HV is not

actively charging, the IC automatically enters a low current

standby mode where supply bias currents are reduced to

< 100μA. If the battery voltage drops 2.5% from the full-

charge ﬂ oat voltage, the LT3652HV engages an automatic

charge cycle restart. The IC also automatically restarts a

new charge cycle after a bad battery fault once the failed

battery is removed and replaced with another battery.

The LT3652HV includes provisions for a battery tem-

perature monitoring circuit. This feature monitors battery

temperature during the charging cycle using a thermistor,

and suspends charging and signals a fault condition if the

battery temperature moves outside a safe charging range

of 0°C to 50°C.

The LT3652HV contains two digital open-collector outputs,

which provide charger status and signal fault conditions.

These binary-coded pins signal battery charging, standby

or shutdown modes, battery temperature faults, and bad

battery faults.

OPERATING PRINCIPLE

BATTERY VOLTAGE

3.3

EFFICIENCY

8.1 9.3 10.5 11.7 12.9 14.14.5 5.7

1688A F01

6.9

= 24V

= 15V

= 12V

BAT

= 2A

BATTERY VOLTAGE

3.3

0.0

0.2

0.4

INPUT CURRENT

1.6

1.8

1.0

1.2

1.4

0.8

0.6

2.0

8.1 9.3 10.5 11.7 12.9 14.14.5 5.7

1688A F02

6.9

= 24V

= 15V

= 12V

INPUT VOLTAGE

17.5

0.0

0.5

CHARGE CURRENT (A)

2.0

1.5

1.0

2.5

17.9 18 18.1 18.2 18.317.6 17.7

1688A F03

17.8

Figure 1. LT3652HV Efﬁ ciency Figure 2. 2A Charge Current Figure 3. Charge Current vs Input Voltage

Using short twisted pair leads for any power connections,

with all loads and power supplies off, refer to Figure 4 for

the proper measurement and equipment setup.

dc1688afa

DEMO MANUAL DC1688A

Figure 4. Proper Measurement Equipment Setup for DC1688A

Follow the procedure below:

1. Jumper and Power Supply Setting:

JP1 = 1 JP4 = 1

JP2 = 0 PS1 = OFF

JP3 = C/10 PS2 = OFF

2. Turn on PS2 and slowly increase the voltage until V

BAT

is 7.5V while monitoring the current into the BAT pin.

If the current is less than 5mA, turn on PS1. Increase

PS1 until V

is 18V while monitoring the input current.

3. Verify the battery charging current is between 250mA

and 350mA. The CHRG LED should be on and the

FAULT LED should be off.

4. Increase PS2 until V

BAT

is 12.0V. Verify the input cur-

rent is between 1.3A and 1.7A, the battery current is

between 1.775A and 2.225A and that the CHRG LED

is on.

5. Increase PS2 until V

BAT

is 14.8V. Verify the battery charging

current is less than 5mA and that the CHRG LED is off.

6. Decrease PS2 until V

BAT

is 13.8V. Verify the battery charging

current is less than 5mA and that the CHRG LED is off.

7. Decrease PS2 until V

BAT

is 12.0V. Verify the battery

current is between 1.775A and 2.225A and that the

CHRG LED is on.

8. Set JP1 to 0. Verify the charging current is less than

5mA and that the FAULT LED and the CHRG LED are off.

9. Set JP1 to 1. Connect a jumper from the NTC pin to

ground. Verify the charging current is less than 5mA

and that the FAULT LED and the CHRG LED are on.

10. Remove the jumper from NTC to ground. Verify the

charging current is between 1.775A and 2.225A and

that the FAULT LED is off and the CHRG LED is on.

11. Turn on LOAD1 and set to 1A. Verify the voltage, Vsys-

tem, on the System Load terminal is approximately

equal to V

. Turn off LOAD1. Decrease PS1 to 14.0V.

12. Verify the battery charging current is less than 5mA

and that the CHRG LED is off.

13. Increase PS1 to 18.5V. Verify the charging current is

between 1.775A and 2.225A and that the CHRG LED

is on. Set JP2 to 1. Decrease PS1 to 17.0V.

14. Set JP4 to 0. Setting JP4 to 0 turns off the charge

current when V

is less than 17.7V. Verify the battery

charging current is less than 5mA and that the CHRG

LED is off.

15. Increase PS1 to 19.0V. Verify the charging current is

between 1.775A and 2.225A and that the CHRG LED

is on. Set JP4 to 1. Set JP2 to 0.

16. Turn off PS1 and PS2.

Note: All Connections from Equipment Should Be Kelvin Connected Directly to the Board Pins Which

They Are Connected to on This Diagram and Any Input, or Output, Leads Should Be Twisted Pair.

QUICK START PROCEDURE

1688a F04

P1-P3 P4-P6

DC1688A

Mfr. #:

Buy DC1688A

Manufacturer:

Analog Devices Inc.

Description:

Power Management IC Development Tools LT3652HVEDD Demo Board - Power Tracking

Lifecycle:

New from this manufacturer.

Delivery:

DHL FedEx Ups TNT EMS

Payment:

T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet

DC1688A