LT1620 Linear Technology, LT1620 Datasheet
LT1620
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LT1620 Summary of contents
Page 1
... The LT1620 overcomes this restric- tion by providing a level-shifted current sense signal, allowing 32V output voltage range. The 16-pin version of the LT1620 contains a program- mable low charging current flag output. This output flag can be used to signal when a Li-Ion battery charging cycle is nearing completion ...
Page 2
... C unless otherwise noted IOUT A SYMBOL PARAMETER Supply V 5V Supply Voltage Active Supply Current CC LT1620GN DC Active Supply Current LT1620S8, LT1620MS8, 1/2 LT1621GN 4. Active Supply Current LT1620S8, LT1620MS8, 1/2 LT1621GN 4.5V V Current Sense Amplifier V Input Common Mode Range CM V Differential Input Voltage Range ID + – (IN – ...
Page 3
... Integration time constant is calculated using 2.5k typical output imped- ance. PROG: Transconductance Amplifier Negative Input. Pro- gram node for average current delivered to load during current mode operation. Average current delivered to load imposes voltage differential at current sense amplifier LT1620/LT1621 MIN TYP MAX UNITS – – ...
Page 4
... The current sense amplifier is a multiple output voltage amplifier with an operational input common mode range from 0V to 32V. The amplifier generates scaled output voltages at the SENSE, AVG and AVG2 (available in LT1620GN) pins. These output signal voltages are refer- enced to the V supply by pulling signal current through CC internal V referred resistors ...
Page 5
... APPLICATIONS INFORMATION In Figure 2, an LT1620MS8 is coupled with an LTC1435 switching regulator in a high performance lithium-ion battery charger application. The LTC1435 switching regu- lator delivers extremely low dropout capable of approximately 99% duty cycle operation. No additional power supply voltage is required for the LT1620 in this application ...
Page 6
... PROG pin ( mentioned above, optimum performance PROG is obtained with (V – 0.8V. The LT1620 is CC PROG biased with a precision 5V supply produced by the LTC1435, enabling use of a simple resistor divider from V ground for a V reference. Using the desired 2.5k ...
Page 7
... BATT(FLOAT) End-of-Cycle Flag Application Figure 3 illustrates additional connections using the LT1620GN, including the end-of-cycle (EOC) flag feature. The EOC threshold is used to notify the user when the required load current has fallen to a programmed value, usually a given percentage of maximum load. ...
Page 8
... LT1620/LT1621 U U APPLICATIONS INFORMATION reduces battery charging current until the external load subsides. In Figure 4 the LT1620 is coupled with an LT1513 SEPIC battery charger IC to create an input overcurrent protected charger circuit. The programming voltage (V – through a resistor divider (R and R P1 supply to ground. In this configuration, if the input current ...
Page 9
... IN – INPUT (mV) ID LT1620/21 • F05b ) Changes Slightly PROG 80mV 130 A OUT – COMMON MODE VOLTAGE (V ) (V) CM LT1620/21 • F05d ) Below (V – 0.5V). This CM CC 5.50 and V PROG2 ) ...
Page 10
... CC I PROG R PROG 5 –IN + )(10,000) OUT PROG R = 40k FOR 1A OUTPUT PROG LT1620/21 • TA01 0.05 I OUT 25V TPS 0.047 F 10k 20k 0 PROG PROG 47k 2N7002 )(20,000) OUT PROG 33k R = 90k FOR 1A OUTPUT PROG LT1620/21 • TA04 ...
Page 11
... TYP LT1620/LT1621 0.189 – 0.196* (4.801 – 4.978 0.229 – 0.244 (5.817 – 6.198) 0.150 – 0.157** (3.810 – 3.988) ...
Page 12
... Step-Down Charger that Allows Charging During Computer Operation and Prevents Wall-Adapter Overload 5V Standby in Shutdown, V Constant Frequency 5V Standby in Shutdown, V Constant Frequency PROTECTED FAULT 1N4148 100k 33k LT1620/21 • TA03 36V, Programmable IN 36V, Programmable IN 36V, Programmable IN 36V, Programmable IN 36V, Programmable IN 16201f LT/GP 0197 7K • PRINTED IN USA ...