LM3420-4.2 NSC [National Semiconductor], LM3420-4.2 Datasheet
LM3420-4.2
Related parts for LM3420-4.2
LM3420-4.2 Summary of contents
Page 1
... LM3420-4.2, -8.2, -8.4, -12.6, -16.8 Lithium-Ion Battery Charge Controller General Description The LM3420 series of controllers are monolithic integrated circuits designed for charging and end-of-charge control for Lithium-Ion rechargeable batteries. The LM3420 is available in five fixed voltage versions for one through four cell charger applications (4.2V, 8.2V/8.4V, 12.6V and 16.8V respec- tively) ...
Page 2
Connection Diagrams and Order Information DS012359-3 *No internal connection, but should be soldered to PC board for best heat transfer. Top View www.national.com 5-Lead Small Outline Package (M5) For Ordering Information See Figure 1 in this Data Sheet See NS ...
Page 3
... REG = mA kHz 70 3 (Notes 1, 2) −40˚ −40˚C T +125˚ LM3420A-4.2 LM3420-4.2 Units Limit Limit (Limits) (Note 5) (Note 5) 4.221/4.242 4.242/4.284 V(max) 4.179/4.158 4.158/4.116 V(min) ± ± ± ± 0. ...
Page 4
... V/V(min) V/V 1500/900 1000/700 V/V(min) V 1.2/1.3 1.2/1.3 V(max) µA 0.5/1.0 0.5/1.0 µA(max) k 220 220 k (max) 132 132 k (min) µV RMS LM3420A-8.4 LM3420-8.4 Units Limit Limit (Limits) (Note 5) (Note 5) V 8.442/8.484 8.484/8.568 V(max) 8.358/8.316 8.316/8.232 V(min) ± ± ± ± 0. %(max) µ ...
Page 5
... V/V(min) 1500/900 1000/700 V/V(min) 1.2/1.3 1.2/1.3 V(max) 0.5/1.0 0.5/1.0 µA(max) 227 227 k (max) 135 135 k (min) µV LM3420A-12.6 LM3420-12.6 Units Limit Limit (Limits) (Note 5) (Note 5) 12.663/12.726 12.726/12.852 V(max) 12.537/12.474 12.474/12.348 V(min) ± ± ± ± 0. ...
Page 6
... REG = 0V 392 = 1 mA kHz 280 ) when soldered to a printed circuit board is approximately 306˚C/W JA resistor into each pin. 6 LM3420A-16.8 LM3420-16.8 Units Limit Limit (Limits) (Note 5) (Note 5) 16.884/16.968 16.968/17.136 V(max) 16.716/16.632 16.632/16.464 V(min) ± ± ...
Page 7
Typical Performance Characteristics 4.2V Bode Plot DS012359-17 8.2V and 8.4V Bode Plot DS012359-20 12.6V Bode Plot DS012359-23 16.8V Bode Plot DS012359-26 Response Time for 4.2V Version DS012359-18 Response Time for 8.2V, 8.4V Versions DS012359-21 Response Time for 12.6V Version DS012359-24 ...
Page 8
Typical Performance Characteristics Regulation Voltage vs Output Voltage and Load Resistance DS012359-29 Regulation Voltage vs Output Voltage and Load Resistance DS012359-32 Regulation Voltage vs Output Voltage and Load Resistance DS012359-35 www.national.com (Continued) Circuit Used for Bode Plots DS012359-30 Quiescent Current ...
Page 9
Typical Performance Characteristics Regulation Voltage vs Output Voltage and Load Resistance DS012359-38 (Continued) 9 www.national.com ...
Page 10
... Lithium-Ion battery charger. The regulated output volt- age is sensed between the IN pin and GROUND pin of the LM3420. If the voltage at the IN pin is less than the LM3420 regulating voltage (V ), the OUT pin sources no current. ...
Page 11
... FIGURE 2. LM3420 Test Circuit Formulas for selecting trim resistor values are shown below, based on the percent of increase (%incr) or percent of de- DS012359-8 crease (%decr) of the output voltage from the nominal volt- age. For LM3420-4.2 R For LM3420-8.2 11 OUT specified in ...
Page 12
... One item to keep in mind when designing with the LM3420 is that there are parasitic diodes present. In some designs, un- der special electrical conditions, unwanted currents may /%incr flow. Parasitic diodes exist from OUT to IN, as well as from 3 GROUND to IN ...
Page 13
... The battery voltage is sensed and buffered by the op-amp section of the LM10C, connected as a voltage follower driv- ing the LM3420. When the battery voltage reaches 8.4V, the LM3420 will begin regulating by sourcing current into R8, which controls the collector current of Q2, which in turn re- duces the gate voltage of Q3 and becomes a constant volt- age regulator for charging the battery ...
Page 14
... LM2575-ADJ. to satisfy the feedback loop. Once the battery voltage reaches 8.4V, the LM3420 takes over and begins to control the feedback pin of the LM2575-ADJ. The LM3420 now regulates the voltage across the battery, and the charger becomes a constant-voltage charger ...
Page 15
Application Circuits (Continued) FIGURE 10. (Fast) Pulsed Constant Current 2-Cell Charger 15 DS012359-15 www.national.com ...
Page 16
... LM2575-ADJ. charger. In this circuit, a second LM3420-8.4 has its V 400 mV (via R2), and is used to limit the output voltage of the charger to 8.8V in the event of a bad battery connection, or the battery is removed or possibly damaged. The LM555 timer is connected as a one-shot, and is used to provide the 5 second charging pulses ...
Page 17
Physical Dimensions For Ordering Information See Figure 1 In This Data Sheet LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND ...