LTC1980 Linear Technology, LTC1980 Datasheet
LTC1980
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LTC1980 Summary of contents
Page 1
... Burst Mode operation and power-down mode allow power density, efficiency and output ripple to be tailored to the application. The LTC1980 provides a complete Li-Ion battery charger with charge termination timer, preset Li-Ion battery volt- ages, overvoltage and undervoltage protection, and user- programmable constant-current charging. Automatic bat- tery recharging, shorted-cell detection, and open-drain C/10 and wall plug detect outputs are also provided ...
Page 2
... BATT1 = 0, BATT2 = 0 BATT1 = 0, BATT2 = 1 (Note 3) BATT1 = 0, BATT2 = 1 (Note 3) BATT1 = Open, BATT2 = Don’t Care Measured from OVP Input BATT2 = 0, BATT1 = BATT2 = 1, BATT1 = ORDER PART TOP VIEW NUMBER SS 24 OVP 23 LTC1980EGN CAOUT SENSE GND BIAS2 18 V BAT 17 TIMER ...
Page 3
... From REGFB Open Measured from OVP to SS, Charger Mode, BATT1 = Open Measured from I to SENSE CAOUT Pin C = 15pF 10V BAT REG C = 1000pF REG REG LTC1980 MIN TYP MAX UNITS 60 mV 2.55 2.7 2.8 V 5.2 5.4 5.65 V 1.0 A 350 mhos 0 – 0.1 V REG ...
Page 4
... Digital Input Current, BATT2 I3 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1980E is guaranteed to meet performance specifications from Specifications over the – operating W U TYPICAL PERFOR A CE CHARACTERISTICS ...
Page 5
... REG V = 3.1V LDO I = 200mA LDO WALL ADAPTER FIGURE 5 IN TIMER 100mV/DIV PIN 17 1.5 2.0 2.5 3.0 (V) IN 1980 G13 LTC1980 Typical Operation with Burst Mode Operation Disabled V REG 50mV/DIV I SENSE 50mV/DIV 1980 G08 V = 3.6V 1 s/DIV BAT V 3.3V REG I = 500mA L MODE = V BIAS1 FIGURE 5 Regulator Output Transient Response— ...
Page 6
... WA to ground sets the threshold which determines if charging can occur. If the wall adapter is below this threshold, the LTC1980 assumes the wall adapter is not present and the charger shuts down. Wall adapter sense threshold is set higher than the DC/DC converter output voltage to insure correct operation ...
Page 7
... This insures that the wall adapter is not loaded down with a large inrush current that could prevent correct ). SENSE battery charger operation. The same capacitor, which sets the soft-start ramp rate, also sets the compensation for the battery float voltage control loop. LTC1980 1980i 7 ...
Page 8
... LTC1980 W BLOCK DIAGRA www.DataSheet4U.com V BIAS1 13 V REF REFERENCE V 18 BAT V MAX + V REF V REG V DD REG – BIAS2 L MODE 16 MODE BURST MODE OPERATION OFF OPEN = BURST MODE OPERATION DISABLE PROGT REF REGFB 3 EA – BATT1 REF ...
Page 9
... The LTC1980 includes a 300kHz DC/DC PWM converter that operates in two modes. The first mode is when the wall adapter is present and the LTC1980 is used to charge the battery using a constant-current/constant-voltage charge scheme. The second mode is when the wall adapter is removed and the battery powers the LTC1980 and the DC/DC converter generates a regulated output voltage ...
Page 10
... When the AC adapter is removed, the LTC1980 operates as a DC/DC PWM converter using the battery for input power to provide a regulated output voltage for the system load. The LTC1980 is a current mode switcher. This means that the switch duty cycle is directly controlled by switch current rather than by output voltage or current. Battery charger operation will be described for the simplified diagram (Figure 3) ...
Page 11
... Figure 4. Battery Charger Current Control Loop , gained up via U6 DC/DC Converter Operation S When the LTC1980 is operating as a DC/DC converter, M1 turns on at the start of the oscillator cycle. When trans- former current reaches a predetermined level set by U10’s output voltage, M1 turns off and M2 turns on. SW2 is in the ...
Page 12
... In applica- tions where an unregulated wall adapter is used but a regulated voltage is needed by the system, an external P- channel MOSFET pass transistor may be added to the LTC1980 to create a low dropout linear regulator. From Figure 5, select the following resistors based on the output voltage V : LDO • ...
Page 13
... PWM supply. This prevents body diode turn on and improves efficiency by eliminating loss from reverse re- covery in these diodes. It also reduces conduction loss during the RGTDR/BGTDR break interval. The LTC1980 can operate to voltages as low as 2.8V. Suitable Schottky diodes include the ZHCS1000 (V 420mV at I most 500mA to 1A output current applications. ...
Page 14
... Figure 5. 4.1V/1A Li-Ion Battery Charger and 3.3V DC/DC Converter 14 V 3.3V REG + C4 5 1nF 1/2 FDC6401N RGTDR V LDODRV LDOFB WA SENSE REG 15 REG 16 MODE LTC1980 9 BATT1 10 BATT2 TIMER BIAS1 BIAS2 0. R12 C8 C10 100k 0.1 F 0.33 F C12 82pF R13 806k D1* ...
Page 15
... TYP .015 .004 .053 – .068 45 (0.38 0.10) (1.351 – 1.727) 0 – 8 TYP .008 – .012 (0.203 – 0.305) LTC1980 .337 – .344* (8.560 – 8.738) .033 (0.838 ...
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... LTC1980 RELATED PARTS www.DataSheet4U.com PART NUMBER DESCRIPTION LT1170/LT1171/LT1172 5A/3A/1.25A Flyback Regulators LT1571 200kHz/500kHz Switching Battery Charger LTC1729 Lithium-Ion Battery Charger Termination Controllers Time or Charge Current Termination, Preconditioning 8-Lead MSOP LTC1730 Lithium-Ion Battery Pulse Charger LTC1731 Lithium-Ion Linear Battery Charger Controller LTC1732 ...