ICS1702EB - Galaxy Power, Inc. - Datasheet.Directory

ICS1702EB

ICS1702 Evaluation Board

General Description

Galaxy Power, Inc.'s ICS1702 Evaluation Board allows quick

evaluation of the ICS1702 Charge Controller for Nickel-Cadmium

and Nickel-Metal Hydride Batteries. The evaluation board provides

the designer an opportunity to both test the ICS1702 and a fast

charge battery charger. The board is self-contained and can provide

a constant current to charge a battery when optional components

are installed.

The board includes resistors that are user-installed to customize

operation for the desired charge rate, discharge pulse current, and

number of cells in the battery pack. The board has a 5V regulator

that provides power to the ICS1702 and the LED display. The

board also has a breadboarding area consisting of a matrix of holes

for user added components.

Before using Galaxy Power, Inc.'s ICS1702 Evaluation Board,

ICS recommends the user review the ICS1702 data sheet to

become familiar with the operation of the controller.

The ICS1702EB can be purchased two ways: ICS1702EB or

ICS1702EB/CR. The difference between these boards is a constant

current linear supply as shown in the board schematic. The

ICS1702EB has an area on the board reserved for these

components. The ICS1702EB/CR contains a kit which includes an

LM317 and associated parts needed to build a current regulator

Setting-up the Board for your

Application

Refer to the evaluation board schematic diagram. The ICS1702

requires that the battery voltage is normalized to the voltage of one

cell, or about 1.2V. To do this, resistors must be installed in the

locations marked R6 and R8. The appropriate values can be

selected from Table 1. An assortment of resistors is provided with

the board.

Table 1

Cells R6 R8

1Open Short

22.0k 2.0k

31.0k 2.0k

41.0k 3.0k

53.0k 12k

62.0k 10k

72.0k 12k

81.3k 9.1k

If the evaluation board is used with battery packs containing more

than eight cells, the resistors can be determined by counting the

number of cells to be charged in series. Then choose either R6 or

R8 and solve for the other resistor using:

R8 = R6* (# of cells -1) or R6 = R8

(# of cells -1)

R7 sets the open circuit (no battery) reference voltage at the

OPREF pin voltage. The purpose of this voltage reference is to

detect the removal of the battery from the charging system. The

voltage at this pin is compared to the voltage at the VIN pin when

the current source is turned on. If the voltage at VIN is greater than

the voltage at OPREF, the ICS1702 assumes the battery has been

removed and the ICS1702 enters the polling detect mode. For

proper operation, the voltage at OPREF must be set between the

(divided down) open circuit voltage produced by the current source

and the maximum normalized battery. As a guide, set the voltage at

OPREF (TP1) to be 200mV to 300mV higher than the maximum

normalized battery voltage. For most batteries, the maximum

normalized battery voltage at full charge is 1.7 to 1.8V, so OPREF

(TP1) should be set at about 2V.

When power is applied to the board, the controller will start a

charge sequence unless a logic low is applied to the RESET

terminal. When RESET is removed by a logic high or open, a

charge sequence will begin.

ICS1702 Evaluation Board

The board provides several low value resistors that may be used to

set the amplitude of the discharge pulse. The resistors can be

installed in any or all of the locations labeled R1, R2, or R3. The

resistor value is calculated by setting the amplitude of the

discharge pulse. The discharge pulse amplitude is typically 2.5

times the charge current based on 1.4V/cell. The required power

rating of the resistor is highest when the Discharge-to-Charge and

Discharge-Only Auxiliary Modes are used. See the ICS1702 data

sheet for additional information. The resistor locations R1, R2, and

R3 are connected in series. The unused locations must have a

jumper to complete the circuit. Not using the discharge pulse

feature will not affect the performance of the ICS1702.

The ICS1702 is capable of operating at nine different charge rates

between 4C (15 minutes) and C/4 (four hours). The charge rate is

selected by installing jumpers in the appropriate locations. Table 2

shows the proper settings to use for the desired charge rate.

Table 2: Charge Rate List

Charge Rate Jumper

S0 Jumper

S1 Topping Charge

pulse Rate Maintenance Charge

Pulse Rate Fast Charge Timer

Duration (after reset)

4C (15 min) 1 & 2 1 & 2 one every 40 sec one every 160 sec 21 min

2C (30 min) 1 & 2 2 & 3 one every 20 sec one every 80 sec 39 min

1.3C (45 min) 1 & 2 None one every 13 sec one every 53 sec 57 min

1C (60 min) 2 & 3 1 & 2 one every 10 sec one every 40 sec 75 min

C/1.5 (90 min) 2 & 3 None one every 7 sec one every 27 sec 110 min

C/2 (120 min) 2 & 3 2 & 3 one every 5 sec one every 20 sec 144 min

C/2.5 (150 min) None 1 & 2 one every 4 sec one every 16 sec 212 min

C/3 (180 min) None None one every 3 sec one every 13 sec 244 min

C/4 (240 min) None 2 & 3 one every 2 sec one every 10 sec 275 min

The ICS1702 has several auxiliary modes available. Table 3

shows the jumper configurations for the auxiliary modes.

Table 3: Mode Select List

Mode Selected Jumper

AUX0 Jumper

AUX1 Mode Operation

Direct Maintenance 2 & 3 1 & 2 Indefinite C/40 maintenance charge

Charging System Test 2 & 3 2 & 3 Charging system test for embedded applications

Ten Hour Timer 1 & 2 1 & 2 Limits total charge including the maintenance charge to 10 hours

Discharge-to-Charge 1 & 2 2 & 3 Battery discharge to 1V/cell followed by the selected charge mode

Condition 1 & 2 None Timed C/10 topping charge followed by a C/40 maintenance charge

Fast Charge None None Normal fast charge

Discharge-Only None 2 & 3 Battery discharge to 1V/cell

ICS1702 Evaluation Board

Current Regulator (CR option)

The ICS1702EB/CR contains an LM317 regulator. The

LM317 is configured as a constant current source. The amplitude

of the current is determined by the value of R15 and the setting of

R16. As an example, with a 2 ohm resistor for R15, the current can

be adjusted with R16 from 0.625A to 1.25A. The LM317 will

regulate a voltage difference of 1.25 volts between the OUT and

ADJ pins.

Operation

Before applying power to the board, ensure that the board is

properly initialized.

• Set the AUX0 and AUX1 jumpers for the desired mode of

operation.

• Set the S0 and S1 jumpers for the correct charge rate.

• If needed, set the DTSEL jumper for the desired termination

method.

• Check to make sure the divider resistors R6 and R8 are of the

correct value to normalize the battery pack voltage to one cell.

• If applicable, choose a value for R15 (see the section on

Current Source).

• If applicable, choose resistors R1, R2 and R3 to obtain the

required discharge current.

After applying power to the board, set the following:

• Adjust the potentiometer R7 for the desired open circuit

reference voltage at the OPREF pin.

• If applicable, set the LM317 charging current by adjusting the

potentiometer R16.

•

Push and hold the reset switch SW1 for at least 700ms. All LEDs

should turn off while the switch is depressed. If fast charge is

selected, the green CHG LED will light. The LED will remain lit

until full charge is detected by the ICS1702. At that moment, the

CHG LED will turn off and the MAINT LED will light, indicating

that the topping charge stage has begun. The MAINT LED will

remain on until a reset is issued either by interrupting the power,

removing the batteries or depressing the reset switch SW1.

If the ten hour timer mode is selected, the LED sequence is the

same as the fast charge sequence explained above. After a

maximum of 10 hours has elapsed (from the time the ICS1702 was

reset), the controller will shut down and the MAINT LED will turn

off.

The ICS1702 has the capability to use either temperature slope

termination, voltage slope termination or both methods

simultaneously. Table 4 shows the termination method and the

jumper settings. Refer to the ICS1702 data sheet for more

information on charge termination methods.

Table 4: Termination Select List

Termination Method Jumper DTSEL

Voltage slope termination only None

Voltage slope and temperature slope

termination 1 & 2

Temperature slope termination only 2 & 3

Power Requirements

The evaluation board uses a regulator to provide +5 volts for the

controller. The regulator allows operation from a DC supply of 8 to

32 volts when the supply is connected to the +V terminal. The

board may also be operated from an external 5 volt supply by

removing the regulator (U2), wiring a jumper between regulator

pins 1 and 3, and by connecting 5 volts directly to the +5V

terminal.

Connections To External Circuitry

A normally closed thermal switch or a thermistor should be

connected to the TS terminal. If a thermal protection device is not

used, the TS terminal must be grounded.

Connect the battery between the +BAT and GND terminals. If

using an external current source, connect the charging current

source and its return between the +CUR and GND terminals. If the

on board current source is used, no connection to the +CUR

terminal is required.

Two charge signals are provided to control external charging

circuitry. CHG is high when the charging current is on. The other

signal CHG is low when the charging current is on.

The charging circuitry should provide a current at an amplitude

that is equal to the product of the battery capacity and the desired

charge rate. For example, to charge a 1.2 ampere hour battery in 30

minutes, the current required would be 2.4 amps or 2C where ‘C’ is

the battery capacity.

It is important to note that the ICS1702 does not control the current

flowing into the battery in any way other than turning it on and off.

The charging current should be constant when using voltage slope

termination. The current may vary when using temperature slope

termination.

ICS1702 Evaluation Board

If either direct maintenance or the condition mode is selected, the

MAINT LED will turn on. The LED will remain on until a reset is

issued either by interrupting the power, removing the batteries or

depressing the reset switch SW1.

If the discharge-only mode is selected, the MAINT LED will flash

at a one second rate until the battery has been discharged. When

the battery is discharged, the controller will shut down and the

MAINT LED will turn off.

If the discharge-to-charge mode is selected, the MAINT LED will

flash at a one second rate until the battery has been discharged.

When the battery is discharged, the appropriate charge indicator

will turn on. See the data sheet for more detailed information on

this auxiliary mode of operation.

Polling for a Battery

Upon power-up or after a reset is issued, any excess charge from

filter capacitors at the +BAT and +CUR terminals is removed with

a series of discharge pulses. After the discharge pulse series is

complete, the voltage at VIN must be greater than 0.5V when a

battery is present. If the voltage at the pin is less than 0.5V, the

ICS1702 assumes no battery is attached, and the polling detect

mode is initiated.

The ICS1702 then applies a 100ms charge pulse. During the pulse,

the ICS1702 monitors the VIN pin to determine if the divided

down terminal voltage is above OPREF. If the battery is present,

the voltage will be clamped below the reference on OPREF when

the current pulse is applied. If a battery is not present, the voltage

at VIN will rise above the reference at OPREF. The POLL LED

lights immediately.

Charge pulses will repeat at one second intervals until the battery is

reinstalled. The POLL LED is active as long as the

ICS1702 is in the polling detect mode. Once a battery is installed,

the ICS1702 will turn off the POLL LED and enter the soft start

stage. The ICS1702 will automatically re-enter the polling detect

mode if the battery is removed during the fast charge, topping

charge, or maintenance charge stages. Any open circuit in the

current path to the battery will initiate the polling detect mode.

When in the topping charge or maintenance charge stages, a charge

pulse may not occur for several seconds. During the period between

charge pulses, the voltage at VIN should be greater than 0.5V if a

battery is attached. If the voltage at VIN is less than 0.5V, the

ICS1702 assumes the battery has been removed, and the polling

detect mode is initiated.

Out-of-Temperature Range

The TEMP LED activates if the battery is either too hot or too cold to

fast charge. If a thermistor is used, the ICS1702 employs internal

voltage references to determine if a battery is hot or cold. Note:

Remove R9 and replace with a jumper when using a thermistor. A

10kΩ @ 25°C thermistor with an external pull-up resistor is

typically used. See the ICS1702 data sheet for additional

information.

If a thermal switch is used, choose a switch that opens at 45°C or

lower. If a thermal protection device is not used, the TS terminal

must be grounded.

GPI strongly recommends the use of a thermal safety device in the

battery pack. One source of thermal switches is Portage Electric

Products, Inc., in North Canton, Ohio; (216) 499-2727. A source of

thermistors is Semetic USA (Ishizuka Electronics Corp.), Babylon,

NY; (516) 587-4086.

Design Considerations

When designing external current source circuitry for use with the

ICS1702, there are several important considerations to make before

starting the design and the PC board layout.

For fast charge rates (1C through 4C), consideration has to be given

to the use of a pulse-width modulated switch mode current source in

order to reduce size and power dissipation.

Switch mode current sources can provide the ability to charge battery

packs that require voltages higher than the primary supply. For

instance, to charge a 24 volt battery from a 12 volt vehicle battery, a

switch mode boost converter could be used.

In general, linear chargers are less complex and more cost effective,

but less efficient than switch mode chargers. For lower charge rates

(C/1.5 through C/4), consideration should be given to using a linear

charger unless the size and ability to dissipate heat are not available.

It is very important that care be taken to minimize noise coupling and

ground bounce. In addition, wires and connectors can add significant

resistance and inductance to the charge and discharge circuits.

ICS1702 Evaluation Board

When designing the printed circuit board, make sure ground and

power traces are wide and bypass capacitors are used right at the

controller pins. Use separate grounds for the signal, charge, and

discharge circuits. Separate ground planes on the component side

of the PC board are recommended. Be sure to connect these

grounds together at the negative lead of the battery only.

For the discharge circuit, keep the physical separation between

power and return (ground) to a minimum to minimize field

radiation effects. This precaution is also applicable to the constant

current source, particularly if it is a switch mode type. Keep the

ICS1702 and the constant current source control circuits outside

the power and return loops described above. These precautions

prevent high circulating currents and coupled noise from disturbing

proper operation.

Galaxy Power Incorporated wants to help create a successful

battery charging solution using the ICS1702. If you need technical

advice or applications information, call the Intelligent Charging

Solutions hotline at (610) 676-0188 x-277.

Ordering Information

ICS1702EB /CR

Device type

ICS1702 Evaluation Board

Ordering Option

blank=populated board

/CR=populated board with regulator kit

ICS1702 Evaluation Board

1011

ICS1702

CHG

DCHG

PFN

MMN

CMN

OTN

SEL0

VSS

AVSS

SEL1MRN

DTSEL

AUX0

AUX1

THERM

OPREF

VIN

VDD

+ 5 V

4.7µF.047µF

+5 V

R16

10k

+ 5 V

100pF

15k

390

POLL

CHG

MAINT

TEMP

Notes:

1) Values are determined by number of cells and actual charge current used ; see text for details.

2) Components within dotted lines can be supplied as a kit for user-installation when ordered; see ordering information.

390

+5 V

R11

ADJ

OUT

LM317

R13

R15

+ 5 V

1 2 3

123 123

123

DTSEL

AUX0

AUX1

+ 5 V

10k

TP1

not

R14

1µF

1kC5

(note 1)

.047µF

C2C1

R10

(note 1)

1k1k

1N5822

+ V

.1µF

(note 1)

2N7000

VIN

GND

VOUT+ VC3

.047µF

U2 (note 6)+ 5 V

CHG

+CUR

+BAT

RESET

GND

R18R12

TP2

+ 5 V

(note 3)

SW1

+ 5 V

3) Remove TS to GND zero ohm resistor and replace R9 with a jumper when using a thermistor. Use of a thermistor

requires an external pull-up resistor to +5V (see ICS1702 data sheet for details).

(note 4)

4) 8 Vdc minimum input

unused

CR1

(not used)

5) Logic level compatible FET

(note 5)(note 2)

6) LM340, AN7805 or equivalent

390390

R17R5

not

used

(note 3)

ICS1702 EVALUATION BOARD REVISION C SCHEMATIC