ISL9203ACRZ Datasheet ISL9203ACRZ, ISL9203ACRZ-T | P10-P12

FN6430.0

February 14, 2007

The Block Diagram, Figure 16, aids in understanding the

operation. The current loop consists of the current amplifier

CA and the sense MOSFET Q

SEN

. The current reference I

is programmed by the IREF pin. The current amplifier CA

regulates the gate of the sense MOSFET Q

SEN

so that the

sensed current I

SEN

matches the reference current I

. The

main MOSFET Q

MAIN

and the sense MOSFET Q

SEN

form a

current mirror with a ratio of 100,000:1, that is, the output

charge current is 100,000 times I

In the CC mode, the current loop tries to increase the charge

current by enhancing the sense MOSFET Q

SEN

, so that the

sensed current matches the reference current. On the other

hand, the adapter current is limited, the actual output current

will never meet what is required by the current reference. As

a result, the current error amplifier CA keeps enhancing the

SEN

as well as the main MOSFET Q

MAIN

, until they are

fully turned on. Therefore, the main MOSFET becomes a

power switch instead of a linear regulation device. The

power dissipation in the CC mode becomes:

where r

DS(ON)

is the resistance when the main MOSFET is

fully turned on. This power is typically much less than the

peak power in the traditional linear mode.

The worst power dissipation when using a current-limited

adapter typically occurs at the beginning of the CV mode, as

shown in Figure 19. The equation 1 applies during the CV

mode. When using a very small PCB whose thermal

impedance is relatively large, it is possible that the internal

temperature can still reach the thermal foldback threshold. In

that case, the IC is thermally protected by lowering the

charge current, as shown by the dotted lines in the charge

current and power curves. Appropriate design of the adapter

can further reduce the peak power dissipation of the

ISL9203A. See the Application Information section of the

ISL6292 data sheet (www.intersil.com) for more information.

Figure 20 illustrates the typical signal waveforms for the

linear charger from the power-up to a recharge cycle. More

detailed Applications Information is given below.

Applications Information

Power on Reset (POR)

The ISL9203A resets itself as the input voltage rises above

the POR rising threshold. The V2P8-pin outputs a 2.8V

voltage, the internal oscillator starts to oscillate, the internal

timer is reset, and the charger begins to charge the battery.

The STATUS pin indicates a LOW logic signal. Figure 20

illustrates the start up of the charger between t

to t

The ISL9203A has a typical rising POR threshold of 3.4V

and a falling POR threshold of 2.4V. The 2.4V falling

threshold guarantees charger operation with a current-

limited adapter to minimize the thermal dissipation.

Charge Cycle

A charge cycle consists of three charge modes: trickle mode,

constant current (CC) mode, and constant voltage (CV)

mode. The charge cycle always starts with the trickle mode

until the battery voltage stays above V

MIN

(2.3V typical) for

15 consecutive cycles of the internal oscillator. If the battery

voltage drops below V

MIN

during the 15 cycles, the 15-cycle

counter is reset and the charger stays in the trickle mode.

The charger moves to the CC mode after verifying the

battery voltage is above V

MIN

When the battery-pack terminal voltage rises to the final

charge voltage V

, the CV mode begins. The terminal

voltage is regulated at the constant V

in the CV mode and

the charge current declines. After the charge current drops

below I

MIN

(1/10 of I

REF

, see Section ““End-of-Charge

(EOC) Current” on page 11 for more detail) the ISL9203A

indicates the end-of-charge with the STATUS pin. The

charging operation does not terminate. Signals in a charge

cycle are illustrated in Figure 20 between points t

to t

The end of charge indicator (STATUS) will not be set if the

charging current is below I

MIN

within the first 16 cycles after

BAT

exceeds the V

RECHRG

voltage. If the charge current is

still below I

MIN

after these 16 cycles, STATUS goes high to

indicate end of charge.

The following events initiate a new charge cycle:

• POR,

• the battery voltage drops below a recharge threshold,

• or, the EN pin is toggled from GND to floating.

Further description of these events are given later in this

data sheet.

FIGURE 19. TYPICAL CHARGE CURVES USING A CURRENT

LIMITED ADAPTER

MIN

REF

/10

LIM

TRICKLE

MODE

CONSTANT CURRENT

MODE

CONSTANT VOLTAGE

MODE

EOC

INPUT VOLTAGE

BATTERY VOLTAGE

CHARGE CURRENT

POWER DISSIPATION

DS ON()

CHARGE

⋅=

(EQ. 2)

ISL9203A

FN6430.0

February 14, 2007

Recharge

After a charge cycle completes, the charger continues to

regulate the output at the constant voltage; but the STATUS

pin indicates that the charging is completed. The STATUS pin

stays high until the battery voltage drops to below the

recharge threshold, V

RECHRG

(see Electrical Specifications).

Then the STATUS pin goes low and a new charge cycle starts

at point t

. The charge cycle ends at point t

with the STATUS

pin again going high, as shown in Figure 20.

Internal Oscillator

The internal oscillator establishes a timing reference. The

oscillation period is programmable with an external timing

capacitor, C

TIME

, as shown in Typical Applications. The

oscillator charges the timing capacitor to 1.5V and then

discharges it to 0.5V in one period, both with 10μA current.

The period T

OSC

is:

(EQ. 3)

A 1nF capacitor results in a 0.2ms oscillation period.The

accuracy of the period is mainly dependent on the accuracy

of the capacitance and the internal current source.

Charge Current Programming

The charge current in the CC mode is programmed by the

IREF pin. The voltage of IREF is regulated to a 0.8V

reference voltage. The charging current during the constant

current mode is 100,000 times that of the current in the

IREF

resistor. Hence, the charge current is,

(EQ. 4)

Table 1 shows the charge current vs. selected R

IREF

values.

The typical trickle charge current is 10% of the programmed

constant charge current. Table 2 shows the trickle charge

current tolerance guidance at given R

IREF

values, when the

battery voltage is between 0V to 2.5V.

NOTE: The values in table 2 and table 1 are not tested and are only

for guidance in selecting resistor values for mass production tests or

in customer’s products.

End-of-Charge (EOC) Current

The EOC current I

MIN

sets the level at which the charger

starts to indicate the end of the charge with the STATUS pin,

as shown in Figure 20. The charger actually does not

terminate charging. In the ISL9203A, the EOC current is

internally set to 1/10 of the CC charge current, that is:

(EQ. 5)

At the EOC, the STATUS signal rises to HIGH and is latched.

The latch is not reset until a recharge cycle or a new charge

cycle starts. The tolerance guidance for the EOC current at

selected R

IREF

values are given in Table 3.

NOTE: The values in table 3 are not tested and are only for guidance

in selecting resistor values for mass production tests or in customer’s

products.

FIGURE 20. OPERATION WAVEFORMS

VIN

V2P8

STATUS

VBAT

CHARGE

AT LEAST 15

CYCLES

POR THRESHOLD

2.8V V

MIN

RECHRG

CHARGE CYCLE

MIN

CHARGE CYCLE

OSC

0.2 10

TIME

⋅⋅= ondssec()

REF

0.8V

IREF

-----------------

× A()

TABLE 1. CHARGE CURRENT vs R

IREF

VALUES

IREF

(kΩ)

CHARGE CURRENT (mA)

MIN TYP MAX

267 ~ 160 17% lower than

TYP Value

= I

REF

in EQ. 5

17% higher than

TYP Value

160 450 500 550

100 720 800 880

88.9 810 900 990

80 900 1000 1100

TABLE 2. TRICKLE CHARGE CURRENT vs R

IREF

VALUES

IREF

(kΩ)

TRICKLE CHARGE CURRENT (mA)

MIN TYP MAX

267 15 30 60

160 30 50 80

100 40 80 120

88.9 45 90 135

80 70 100 150

TABLE 3. EOC CURRENT vs R

IREF

VALUES

IREF

(kΩ)

EOC CURRENT (mA)

MIN TYP MAX

267 15 30 60

160 30 50 80

100 40 80 120

88.9 45 90 135

80 70 100 150

MIN

------

REF

⋅=

ISL9203A

FN6430.0

February 14, 2007

Charge Current Thermal Foldback

Over-heating is always a concern in a linear charger. The

maximum power dissipation usually occurs at the beginning

of a charge cycle when the battery voltage is at its minimum

but the charge current is at its maximum. The charge current

thermal foldback function in the ISL9203A frees users from

the over-heating concern.

Figure 21 shows the current signals at the summing node of

the current error amplifier CA in the Block Diagram. I

is the

reference. I

is the current from the Temperature Monitoring

block. The I

has no impact on the charge current until the

internal temperature reaches approximately +100°C; then I

rises at a rate of 1µA/°C. When I

rises, the current control

loop forces the sensed current I

SEN

to reduce at the same

rate. As a mirrored current, the charge current is 100,000

times that of the sensed current and reduces at a rate of

100mA/°C. For a charger with the constant charge current

set at 1A, the charge current is reduced to zero when the

internal temperature rises to +110°C. The actual charge

current settles between +100°C to +110°C.

Usually the charge current should not drop below I

MIN

because of the thermal foldback. For some extreme cases if

that does happen, the charger does not indicate end-of-

charge unless the battery voltage is already above the

recharge threshold.

2.8V Bias Voltage

The ISL9203A provides a 2.8V voltage for biasing the

internal control and logic circuit. This voltage is also

available for external circuits such as the NTC thermistor

circuit. The maximum allowed external load is 2mA.

Indications

The ISL9203A has two indications: the input presence and

the charge status. The input presence is indicated by the

V2P8 pin and the charge status is indicated by the STATUS

pin. Figure 22 shows the V2P8 pin voltage vs. the input

voltage.

STATUS Pull-Up Resistor

The STATUS pin is an open-drain output that need an

external pull-up resistor. It is recommended that this be

pulled up to the input voltage or the 2.8V from the V2P8 pin.

If the STSTUS pin has to be pulled up to other voltages, the

user needs to examine carefully whether or not the ESD

diodes will form a leakage current path to the battery when

the input power is removed. If the leakage path does exist,

an external transistor is required to break the path.

Figure 23 shows the implementation. If the STATUS pin is

directly pulled up to the VCC voltage (not shown in Figure 23),

a current will flow from the VCC to the STATUS pin, then

through the ESD diode to the VIN pin. Any leakage on the VIN

pin, caused by an external or internal current path, will result

in a current path from VCC to ground.

The N-Channel MOSFET Q

buffers the STATUS pin. The

gate of Q

is connected to VIN or the V2P8 pin. When the

STATUS pin outputs a logic low signal, Q

is turned on and

its drain outputs a low signal as well. When STATUS is high

impedance, R

pulls the Q

drain to high. When the input

power is removed, the Q

gate voltage is also removed, thus

the Q

drain stays high.

Shutdown

The ISL9203A can be shutdown by pulling the EN pin to

ground. When shut down, the charger draws typically less

than 30µA current from the input power and the 2.8V output

at the V2P8 pin is also turned off. The EN pin needs be

driven with an open-drain or open-collector logic output, so

that the EN pin is floating when the charger is enabled. If the

EN pin is driven by an external source, the POR threshold

voltage will be affected.

FIGURE 21. CURRENT SIGNALS AT THE AMPLIFIER CA INPU

TEMPERATURE+100°C

SEN

FIGURE 22. THE V2P8 PIN OUTPUT vs THE INPUT VOLTAGE

AT THE VIN PIN. VERTICAL: 1V/DIV,

HORIZONTAL: 100ms/DIV

3.4V

2.4V

2.8V

V2P8

ISL9203A

P1-P3 P4-P6 P7-P9 P10-P12 P13-P14

ISL9203ACRZ

Mfr. #:

Buy ISL9203ACRZ

Manufacturer:

Renesas / Intersil

Description:

Battery Management BATRY CHRGR 3X3 10LD 53437A02

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ISL9203ACRZ

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