5

LTC1759

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: This limit is greater than the absolute maximum for the charger.

Therefore, there is no effective limitation on voltage when this option is

selected. If the charger is requested to charge with a higher voltage than

the nominal limit, the VOLTAGE_OR bit will be set.

Note 3: Total system accuracy from SMBus request to output voltage or

output current.

Note 4: Test Circuit #1.

Note 5: Voltage accuracy is calculated using measured reference voltage,

ratio.

Note 6: When supply and battery voltage differential is low, high oscillator

duty cycle is required. The LTC1759 has a unique design to achieve duty

the comparator threshold, will TGATE be turned off. See Applications

Information section.

Note 7: Power failure bit is set when the battery voltage is above 89% of

Note 8: The charger provides wake-up current when a battery is inserted

into the connector, prior to the battery requesting charging current and

voltage. See Smart Battery Charger Specification (Revision 1.0), section

6.1.3 and 6.1.8.

Note 9: In system start-up, C6 (boost capacitor) has no charge stored in it.

The LTC1759 will keep TGATE off, and turn BGATE on for 0.2

µs, thus

Note 10: Refer to Smart Battery Charge Specification (Revision 1.0),

section 6.1.2.

Note 11: Maximum total external capacitance on RNR and THERM pins

is 75pF.

Note 12: SMBus operation guaranteed by design from –40

°C to 85°C.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Charger Timing

1nF Load

25

ns

TGATE, BGATE Peak Drive Current

10nF Load

1

A

Regulator Switching Frequency

q

170

200

230

kHz

Synchronization Frequency

q

240

280

kHz

Maximum Duty Cycle in Start-Up Mode (Note 9)

q

85

90

%

q

140

175

210

sec

Cold or Underrange Battery

SMBus Timing (refer to System Management Bus Specification, Revision 1.0, section 2.1 for timing diagrams) (Note 12)

q

4

µs

q

4.7

µs

q

1000

ns

q

30

300

ns

SMBus Accelerator Boosted Pull-Up Current

q

1

2.5

mA

q

4.7

µs

q

4.0

µs

q

250

ns

SDA to SCL Falling-Edge Hold Time,

q

300

ns

q

140

175

210

sec

ChargingCurrent() and ChargingVoltage()

Commands (Note 10)