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Part: LT1620CGN
Category:
Power Management
-> Battery Management
-> Battery Chargers
-> Current Sense Amps for CC/CV Chargers
Description: LT1620, Rail-to-rail Current Sense Amplifier
Company: Linear Technology Corporation
Datasheet: Download LT1620CGN datasheet File size : 550 kB
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Datasheet text preview:
LT1620/LT1621 Rail-to-Rail Current Sense Amplifier
FEATURES
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DESCRIPTIO
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Accurate Output Current Programming Usable in Charging Applications Up to 32V Output Programmable Load Current Monitor for End-ofCharging-Cycle Notification (16-Pin Version) Dual Function IC (LT1621) Allows Convenient Integration of Load and Input Current Sensing Level-Shifted Current Sense Output for Current Mode PWM Controllers Can be Used for NiCd, NiMH, Lead-Acid and LithiumIon Battery Charging Greater than 96% Efficiency Possible in Charger Applications High Output Currents Possible: > 10A Easily Obtained
The LT ®1620 simplifies the design of high performance, controlled current battery charging circuits when used in conjunction with a current mode PWM controller IC. The LT1620 regulates average output current independent of input and output voltage variations. Output current can be easily adjusted via a programming voltage applied to the LT1620's PROG pin. Most current mode PWM controllers have limited output voltage range because of common mode limitations on the current sense inputs. The LT1620 overcomes this restriction by providing a level-shifted current sense signal, allowing a 0V to 32V output voltage range. The 16-pin version of the LT1620 contains a programmable low charging current flag output. This output flag can be used to signal when a Li-Ion battery charging cycle is nearing completion. The LT1621 incorporates two fully independent current control circuits for dual loop applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
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High Current Battery Chargers High Output Voltage DC/DC Converters Constant Current Sources Overcurrent Fault Protectors
TYPICAL APPLICATI
(VBATT + 0.5V) TO 32V VIN S LTC1435 YNCB RONOUS H R UCK EGULATOR ITH SENSE INTVCC 0.1µF 6 VCC 1 8 SENSE AVG 2 7 4 IOUT PROG L T1620MS8 3 GND 5 IN IN + 0.1µF 1 3k % 15.75k % FB SW 27µH
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VIN
3 22µF ×5V 2
IBATT TO 4A VBATT 0 1.43M .1%
0.025
3 22µF 5V
EFFICIENCY (%)
+
0 110k .1%
LT1620/21 · F01
SIMPLIFIED SCHEMATIC. SEE FIGURE 2 FOR COMPLETE SCHEMATIC
Figure 1. Low Dropout, High Current Li-Ion Battery Charger
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Efficiency
100 VIN = 24V VBATT = 16V 95 VBATT = 12V 90 VBATT = 6V 85 80 75 0 1 3 4 2 BATTERY CHARGE CURRENT (A) 5
1620/21 · TA02
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1
LT1620/LT1621 ABSOLUTE AXI U RATI GS (Referenced to Ground) (Note 1)
Sense Amplifier Input Common Mode ....... 0.3V to 36V Operating Ambient Temperature Range Commercial ........... 0°C to 70°C Industrial ........... 40°C to 85°C Storage Temperature Range ....... 65°C to 150°C Lead Temperature (Soldering, 10 sec)........ 300°C Power Supply Voltage: VCC .. 0.3V to 7V Programming Voltage: PROG, PROG2 ... 0.3V to VCC + 0.3V (7V Max) IOUT, SENSE, AVG, AVG2, MODE Voltage ....... 0.3V to VCC + 0.3V (7V Max)
PACKAGE/ORDER I FOR ATIO
TOP VIEW SEINSE 1 2 G UT 3 O IND 4
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7 8 6 5
P AVG VROG I CC N+
SENN E 1 S2 IC3 N OUT 4
N
GC 5 M ND 6
S8 PACKAGE S8 PACKAGE 8-LEAD PLASTIC MSOP 8-LEAD PLASTIC SO JA = 250°C/W (MS) JA = 120°C/W (S)
ON E 7 D IC 8 N
ORDER PART NUMBER LT1620CS8 LT1620IS8 LT1620CMS8 MS8 PART MARKING BC
Consult factory for Military grade parts.
GN PACKAGE 16-LEAD PLASTIC SSOP JA = 149°C/W
ORDER PART NUMBER LT1620CGN LT1620IGN
ELECTRICAL CHARACTERISTICS
VIN+ = 16.8V, VCC = 5V, VIOUT = 2V, TA = 25°C unless otherwise noted.
SYMBOL PARAMETER Supply VCC 5V Supply Voltage I CC DC Active Supply Current LT1620GN DC Active Supply Current LT1620S8, LT1620MS8, 1/2 LT1621GN DC Active Supply Current LT1620S8, LT1620MS8, 1/2 LT1621GN Current Sense Amplifier VCM Input Common Mode Range Differential Input Voltage Range V ID (IN+ IN ) VOSSENSE Input Offset - Measured at ×1 Output (VSENSE) CONDITIONS
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SENSE = AVG = PROG = PROG2 = VCC 4.5V VCC 5.5V, IN+ IN = 100mV SENSE = AVG = PROG = VCC 4.5V VCC 5.5V, IN+ IN = 100mV SENSE = AVG = PROG = VCC 4.5V VCC 5.5V, IN+ IN = 0mV
0V VCM 32V VCC VCM 32V VID = 80mV
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TOP VIEW 16 NVG 15 P C 14 PROG 13 AROG2 12 VVG2 11 NCC 9 IC 0 A+ N
TOP VIEW 2 PROG A 1 AVG A 3 SENSE A 4 I GOUT A 5 ND B 6 IN B IN + B VCC B GN PACKAGE 16-LEAD PLASTIC SSOP
JA = 149°C/W
16 I CC A V 15 N+ A 14 IN A 13 GND A 12 S UT B IO 11 ENSE B 9 AVG B 0 PROG B
7 8
ORDER PART NUMBER LT1621CGN LT1621IGN
MIN 4.5
TYP 5.0 2.8 2.3
MAX 5.5 3.8 4.0 3.3 3.7 1.9 2.1 32 125 5 6
UNITS V mA mA mA mA mA mA V mV mV mV
q q
1.3
q q q
0 0 5 6
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LT1620/LT1621
IN+ = 16.8V, VCC = 5V, VIOUT = 2V, TA = 25°C unless otherwise noted.
SYMBOL PARAMETER Current Sense Amplifier Input Offset - Measured at ×10 Output VOSAVG (VAVG) Input Offset - Measured at × 20 Output (VAVG2) VSENSE No-Load Output Offset + IB(IN , IN ) Input Bias Current (Sink) VOSAVG2 Input Bias Current (Source) Transconductance Amplifier Amplifier Transconductance gm
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ELECTRICAL CHARACTERISTICS
CONDITIONS VCC VCM 32V 35mV VID 125mV VCM = 0V, VID = 80mV VCC VCM 32V 0V VID 35mV 0V VCM 32V, VID = 0V, Referenced to VCC VCC VCM 32V (Note 2) VCM = 0V (Note 2)
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MIN 3 4 10 3 4 0.1 200 185
TYP
MAX 3 4 15 3 4
UNITS mV mV mV mV mV mV µA µA mA mA µmho µmho dB V V V V nA mV mV V mV nA V V
q q q q q
3 270 4.0
400 430 5.25 5.50 4000 4800 0.15 0.30 0.65 VCC 7 8 VCC 0.15
AV VOLIOUT
Amplifier Voltage Gain IOUT Saturation Limit (Sink)
1V VIOUT 3V IIOUT = 50µA IIOUT = 200µA IIOUT = 1mA Measured at PROG Pin IIOUT = 130µA
3000 2200 60
3500 80 0.05 0.10 0.35 20
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VPROG I BPROG VOSPROG
PROG Input Range Input Bias Current Input Offset Voltage (VAVG VPROG) End-of-Cycle Comparator VPROG2 PROG2 Input Range VHYST Input Hysteresis IBPROG2 Input Bias Current VOLMODE Output Logic Low Output (Sink)
VCC 1.25 7 8 VCC 2.5 15 20 0.1 0.5
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Measured at AVG2 Pin Measured at PROG2 Pin IMODE = 0.5mA IMODE = 10mA
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0.5 1.2
The q denotes specifications which apply over the full operating temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Input bias currents are disabled when VCC is removed, even with common mode voltage present at IN+, IN.
PI FU CTIO S
VCC: 5V ±10% Power Supply Input. IN+ : Sense Amplifier Positive Input. Typically connected to inductor side of current sense resistor. Common mode voltage range is 0V to 32V. IN: Sense Amplifier Negative Input. Typically connected to load side of current sense resistor. Common mode voltage range is 0V to 32V. SENSE: Sense Amplifier AV = 1 Output. Used as levelshifted output for PWM controller current sense input. The sense output is designed to have an inherent offset to ensure continuity around zero inductor current. Typical output is 3mV with differential input voltage (IN+ IN) = 0. A V G : Sense Amplifier A V = 10 Output and Transconductance Amplifier Positive Input. Used as integration node for average current control. Integration time constant is calculated using 2.5k typical output impedance. PROG: Transconductance Amplifier Negative Input. Program node for average current delivered to load during current mode operation. Average current delivered to load imposes voltage differential at current sense amplifier
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