LT1512 Linear Technology, LT1512 Datasheet
LT1512
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LT1512 Summary of contents
Page 1
... In addition, these to- pologies allow charging even when the input voltage is lower than the battery voltage. Maximum switch current on the LT1512 is 1.5A. This allows battery charging currents for a single lithium-ion cell. Accuracy constant-voltage mode is perfect for lithium battery applications. Charging cur- rent can be easily programmed for all battery types ...
Page 2
... Storage Temperature Range ................ – 150 C Ambient Temperature Range LT1512C (Note 3) .................................... LT1512I .............................................. – Operating Junction Temperature Range LT1512C (Note 3) ............................ – 125 C LT1512I ............................................ – 125 C Short Circuit ......................................... 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL C ...
Page 3
... IN 2.7V V 25V, V 0. 125 C J – (LT1512I) J 2.7V V 25V S/S the ambient temperature range – are available as industrial parts with an “I” suffix. Maximum allowable ambient temperature may be limited by power dissipation. Parts may not necessarily be operated simultaneously at maximum power dissipation and maximum ambient temperature ...
Page 4
... GND pin is connected. GND S, GND: The LT1512 uses separate ground pins for switch current (GND) and the control circuitry (GND S). This isolates the control ground from any induced voltage created by fast switch currents ...
Page 5
... LT1512. This low dropout design allows input voltage to vary from 2.7V to 25V. A 500kHz oscillator radiation and voltage spikes. In particular, the path in Figure 1 which includes SW to C2, D1, C1 and around to the LT1512 ground pin should be as short as possible to minimize voltage spikes at switch turn-off LOW DROPOUT 2 ...
Page 6
... R3 in Figure 1. The average current through R3 is always identical to the current delivered to the battery. The LT1512 current limit loop will servo the voltage across R3 to – 100mV when the battery voltage is below the voltage limit set by the output divider R1/R2. Constant current charging is therefore set at 100mV/R3 ...
Page 7
... Maximum input voltage for the circuit in Figure 1 is partly determined by battery voltage. A SEPIC converter has a maximum switch voltage equal to input voltage plus output voltage. The LT1512 has a maximum input voltage of 30V and a maximum switch voltage of 40V, so this limits maximum input voltage to 30V, or 40V – less. Maximum V = 40V – ...
Page 8
... Double-Sided (Vias Connect to the Backside of Ground Plane. Dash Lines Indicate Interconnects on Backside. Demo Board Uses This Layout, Except that R5 Has Been Added to Increase Phase Margin) Figure 4. LT1512 Suggested Layouts for Critical Thermal and Electrical Paths equal to input voltage. RMS ripple current in the coupling capacitor has a maximum value of about 0 ...
Page 9
... The negative voltage is converted to a current by R5 and R6 and filtered by C7. This current multiplied by R4 generates a voltage that subtracts from the 100mV sense voltage of the LT1512. This is not a high precision technique because of the errors in V the diode voltage, but it can typically be used to adjust charging current over a 20% to 100% range with good repeatability (full charging current accuracy is not affected) ...
Page 10
... Applications Department is always ready to lend a helping hand. For additional informa- tion refer to the LT1372 data sheet. This part is identical to the LT1512 except for the current amplifier circuitry. U Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead PDIP (Narrow 0 ...
Page 11
... Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.228 – 0.244 (5.791 – 6.197) 0.053 – 0.069 (1.346 – 1.752) 0 – 8 TYP 0.014 – 0.019 (0.355 – 0.483) LT1512 0.189 – 0.197* (4.801 – 5.004 0.150 – 0.157** (3.810 – 3.988) ...
Page 12
... The circuit in Figure 6 will provide adapter current limiting to ensure that the battery charger never overloads the adapter. In addition, it adjusts charging current to a lower value if other system power increases to the point where the adapter would be overloaded. This allows the LT1512 R6 WALL 0.2 ADAPTER ...