LTC1759 データシートの表示（PDF） - Linear Technology

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LTC1759

Smart Battery Charger

Linear Technology 

LTC1759

ELECTRICAL CHARACTERISTICS

The q denotes specifications which apply over the full operating temperature range (TJ = 0°C to 100°C), otherwise specifications are

TA = 25°C. VCC = DCIN = 18V, VBAT1, 2 = 12.6V, VDD = 3.3V unless otherwise specified.

PARAMETER

Charger Timing

VTGATE, VBGATE Rise/Fall Time

TGATE, BGATE Peak Drive Current

Regulator Switching Frequency

Synchronization Frequency

CONDITIONS

1nF Load

10nF Load

MIN TYP MAX

25

1

q 170

200

230

q 240

280

UNITS

ns

A

kHz

kHz

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

tTIMEOUT for Wake-Up Charging a

Cold or Underrange Battery

q 85

90

%

q 140

175

210

sec

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

SCL Serial Clock High Period (tHIGH)

SCL Serial Clock Low Period (tLOW)

SDA/SCL Rise Time (tr)

SDA/SCL Fall Time (tf)

SMBus Accelerator Boosted Pull-Up Current

Start Condition Setup Time (tSU:STA)

Start Condition Hold Time (tHD:STA)

SDA to SCL Rising-Edge Setup Time (tSU:DAT)

SDA to SCL Falling-Edge Hold Time,

Slave Clocking in Data (tHD:DAT)

tTIMEOUT Between Receiving Valid

ChargingCurrent() and ChargingVoltage()

Commands (Note 10)

IPULLUP = 350µA, CLOAD = 150pF

IPULLUP = 350µA, CLOAD = 150pF

CLOAD = 150pF

VDD = 3V

q

4

µs

q 4.7

µs

q

1000

ns

q 30

300

ns

q

1

2.5

mA

q 4.7

µs

q 4.0

µs

q 250

ns

q 300

ns

q 140

175

210

sec

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,

obtained from VSET pin using Test Circuit #2, and VDAC resistor divider

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

cycle greater than 99% by skipping cycles. Only when VBOOST drops below

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

the power adapter voltage (VDCIN).

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 0.2µs, thus

charging C6. A comparator senses VBOOST and switches to the normal

PWM mode when VBOOST is above its threshold.

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.

5

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