Features n Input Offset otage: 3µ (Max) n Sense Inputs Up to 8 n.5 Gain Accuracy n Pin Seectabe Gain:, 2.5, 2, 25,, 5/ n Separate Power Suppy: 2.7 to 36 n Operating Current: 6µA n Sense Input Current ( CC Powered Down): na n Reverse Battery Protected to 8 n Buffered Output n Noise Fitering Input n C to 25 C Operating Temperature Range n Avaiabe in 8-Lead DFN and MSOP Packages Appications n Battery Monitoring n Fuse Monitoring n Portabe and Ceuar Phones n Portabe Test/Measurement Systems L, LT, LTC, LTM, Linear Technoogy, the Linear ogo and Over-The-Top are registered trademarks of Linear Technoogy Corporation. A other trademarks are the property of their respective owners. LT6 Precision, Gain Seectabe High Side Current Sense Ampifier Description The LT 6 is a compete micropower, precision, high side current sense ampifier. The LT6 monitors unidirectiona currents via the votage across an externa sense resistor. Fixed gains of, 2.5, 2, 25,, 5/ are obtained by simpy strapping or foating two gain seect pins. Gain accuracy is better than.5 for a gains. The LT6 sense inputs have a votage range that extends from. to 8, and can withstand a differentia votage of the fu suppy. This makes it possibe to monitor the votage across a MOSFET switch or a fuse. The part can aso withstand a reverse battery condition on the inputs. Input offset is a ow 3µ. CMRR and PSRR are in excess of 5, resuting in a wide dynamic range. A fiter pin is provided to easiy impement signa fitering with a singe capacitor. The LT6 has a separate suppy input, which operates from 2.7 to 36 and draws ony 6µA. When CC is powered down, the sense pins are biased off. This prevents oading of the monitored circuit, irrespective of the sense votage. The LT6 is avaiabe in an 8-ead DFN and MSOP package. Typica Appication A to 33A High Side Current Monitor with 2kHz Frequency Rooff. TO 8 SUPPLY LOAD 8 R SENSE 3mΩ LT6 3 CONFIGURED FOR GAIN = 25/ 2 7 6 CC A A2 EE 3 22pF 5 6 TAa = 2.5 I SENSE = 33A INPUT OFFSET OLTAGE ().5..5.5. Input Offset otage vs Sense Input otage ENSE = CC = 3.5 5 5 2 25 3 35 5 SENSE INPUT OLTAGE () 5 6 TAb 6fc
LT6 Absoute Maximum Ratings Differentia Sense otage... ±8 Tota, to EE... 8 Tota CC Suppy otage from EE... 36 Output otage... ( EE ) to ( EE 36) Output Short-Circuit Duration (Note 3)... Continuous Operating Temperature Range (Note ) LT6C... C to 85 C LT6I... C to 85 C LT6H... C to 25 C Package/Order Information (Notes, 2) Specified Temperature Range (Note 5) LT6C... C to 85 C LT6I... C to 85 C LT6H... C to 25 C Storage Temperature Range... DFN... 65 C to 25 C MSOP... 65 C to 5 C Lead Temperature (Sodering, sec) MSOP... 3 C TOP IEW CC EE 2 3 9 DD PACKAGE 8-LEAD (3mm 3mm) PLASTIC DFN T JMAX = 25 C, θ JA = 3 C/W EXPOSED PAD (PIN 9) IS EE, MUST BE SOLDERED TO PCB 8 7 6 5 A A2 CC EE 2 3 TOP IEW 8 S 7 A 6 A2 5 MS8 PACKAGE 8-LEAD PLASTIC MSOP T JMAX = 5 C, θ JA = 25 C/W Order part number DD part marking* Order part number MS part marking* LT6CDD LT6IDD t6hdd bmw bmw bmw Order Options Tape and Ree: Add #TR Lead Free: Add #PBF Lead Free Tape and Ree: Add #TRPBF Lead Free Part Marking: http://www.inear.com/eadfree/ LT6CMS8 LT6IMS8 t6hms8 LTbmv tbmv tbmv Consut LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grades are identified by a abe on the shipping container. Eectrica Characteristics The denotes specifications which appy over the temperature range C T A 7 C (LT6C), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS S, S Sense Ampifier Suppy otage CC = 2.7. 8 ENSE Input Sense otage Fu Scae ENSE = S S, CC = 3, A = / ENSE = S S, CC = 5, A = / OS Input Offset otage (MS Package) I OUT = 3 3 5 35 55 ±8 3 5 ±8 35 55 Input Offset otage (DD Package) I OUT = OS TC Temperature Coefficient of OS (Note 6).5 3 µ/ C µ µ µ µ 2 6fc
ELECTRICAL CHARACTERISTICS The denotes specifications which appy over the temperature range C T A 7 C (LT6C), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) LT6 SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS A Gain, /ENSE ENSE = 5 to 8, A = / LT6MS8 LT6DD8 9.95 9.9.5.6 / / 9.9. / = 8, ENSE = 5 to 8, A = / 9.9. / Output otage Gain Error (Note 7) ENSE = 5 to 8, A =, 2.5, 2, 25,, 5/ LT6MS8 LT6DD8 = 8, ENSE = 5 to 8,.. A =, 2.5, 2, 25,, 5/ CMRR Sense Input Common Mode ENSE = 5, CC = 2.7, =. to 36 5 2 Rejection Ratio 2 CC PSRR CC Suppy Rejection Ratio ENSE = 5, = 36, CC = 3 to 3 5 2 2 CC Suppy otage CC 2.7 36 BW Bandwidth A = /, f O = 3, CC = 5 A = 5/, f O = 3, CC = 5 t S Output Setting to Fina aue ENSE = to 5 µs I S (O), I S (O) Sense Input Current ENSE =.5 µa I CC(O) CC Suppy Current ENSE = 6 3 µa SR Sew Rate (Note 8) CC = 5, ENSE = 26 to 38, A = 5/.3.5 /µs.2.5 /µs I SC Short-Circuit Current I SC, I SC 8 5 ma Reverse Suppy I S(TOTAL) = 2µA, CC = Open 5 6 O(MIN) Minimum Output otage ENSE =, No Load ENSE = S S =, A = 5/, No Load O(MAX) Output High (Referred to CC ) A = 5/, ENSE =, I L = ENSE =, I L = µa ENSE =, I L = 5µA ENSE =, I L = ma.5.6. 2 5 5 5 5 I S, I S (Off) Sense Input Current (Power Down) CC =, = 8, ENSE =. µa 75 85 25 75.5.6. 3 25 25 5 25 khz khz The denotes specifications which appy over the temperature range C T A 85 C (LT6I), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS S, S Sense Ampifier Suppy otage CC = 2.7. 8 ENSE Input Sense otage Fu Scae ENSE = S S, CC = 3, A = / ENSE = S S, CC = 5, A = / OS Input Offset otage (MS Package) I OUT = 3 3 55 35 6 ±8 3 55 ±8 35 6 Input Offset otage (DD Package) I OUT = OS TC Temperature Coefficient of OS (Note 6).5 3 µ/ C µ µ µ µ 6fc 3
LT6 Eectrica Characteristics The denotes specifications which appy over the temperature range C T A 85 C (LT6I), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS A Gain, /ENSE ENSE = 5 to 8, A = / LT6MS8 LT6DD8 9.95 9.9.5.6 / / 9.9. / = 8, ENSE = 5 to 8, A = / 9.9. / Output otage Gain Error (Note 7) ENSE = 5 to 8, A =, 2.5, 2, 25,, 5/ LT6MS8 LT6DD8 = 8, ENSE = 5 to 8,.. A =, 2.5, 2, 25,, 5/ CMRR Sense Input Common Mode ENSE = 5, CC = 2.7, =. to 36 5 2 Rejection Ratio 2 CC PSRR CC Suppy Rejection Ratio ENSE = 5, = 36, CC = 3 to 3 5 2 2 CC Suppy otage CC 2.7 36 BW Bandwidth A = /, f O = 3, CC = 5 A = 5/, f O = 3, CC = 5 t S Output Setting to Fina aue ENSE = to 5 µs I S (O), I S (O) Sense Input Current ENSE =.5 µa I CC(O) Suppy Current ENSE = 6 5 µa SR Sew Rate (Note 8) CC = 5, ENSE = 26 to 38, A = 5/.3.5 /µs.2.5 /µs I SC Short-Circuit Current I SC, I SC 8 5 ma Reverse Suppy I S(TOTAL) = 2µA, CC = Open 5 6 O(MIN) Minimum Output otage ENSE =, No Load ENSE = S S =, A = 5/, No Load O(MAX) Output High (Referred to CC ) A = 5/, ENSE =, I L = ENSE =, I L = µa ENSE =, I L = 5µA ENSE =, I L = ma.5.6. 2 5 5 5 5 I S, I S (Off) Sense Input Current (Power Down) CC =, = 8, ENSE =. µa 75 85 25 75.5.6. 3 25 25 5 25 khz khz The denotes specifications which appy over the temperature range C T A 25 C (LT6H), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS S, S Sense Ampifier Suppy otage CC = 2.7. 8 ENSE Input Sense otage Fu Scae ENSE = S S, CC = 3, A = / ENSE = S S, CC = 5, A = / OS Input Offset otage (MS Package) I OUT = 3 3 6 35 65 ±8 3 6 ±8 35 65 Input Offset otage (DD Package) I OUT = OS TC Temperature Coefficient of OS (Note 6).5 5 µ/ C µ µ µ µ 6fc
LT6 Eectrica Characteristics The denotes specifications which appy over the temperature range C T A 25 C (LT6H), otherwise specifications are. CC = 5, EE =, = CC. uness otherwise specified. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS A Gain, /ENSE ENSE = 5 to 8, A = / LT6MS8 LT6DD8 9.95 9.9.5.6 / / 9.9. / = 8, ENSE = 5 to 8, A = / 9.9. / Output otage Gain Error (Note 7) ENSE = 5 to 8, A =, 2.5, 2, 25,, 5/ LT6MS8 LT6DD8 = 8, ENSE = 5 to 8,.. A =, 2.5, 2, 25,, 5/ CMRR Sense Input Common Mode ENSE = 5, CC = 2.7, =. to 36 5 2 Rejection Ratio 2 CC PSRR CC Suppy Rejection Ratio ENSE = 5, = 36, CC = 3 to 3 5 2 95 2 CC Suppy otage CC 2.7 36 BW Bandwidth A = /, f O = 3, CC = 5 A = 5/, f O = 3, CC = 5 t S Output Setting to Fina aue ENSE = to 5 µs I S (O), I S (O ) Sense Input Current ENSE =.5 µa I CC(O) Suppy Current ENSE = 6 7 µa SR Sew Rate (Note 8) CC = 5, ENSE = 26 to 38, A = 5/.3.5 /µs.2.5 /µs I SC Short-Circuit Current I SC, I SC 8 5 ma Reverse Suppy I S(TOTAL) = 2µA, CC = Open 5 6 O(MIN) Minimum Output otage ENSE =, No Load ENSE = S S =, A = 5/, No Load O(MAX) Output High (Referred to CC ) A = 5/, ENSE =, I L = ENSE =, I L = µa ENSE =, I L = 5µA ENSE =, I L = ma.5.6. 2 5 5 5 5 I S, I S (Off) Sense Input Current (Power Down) CC =, = 8, ENSE =. µa 75 85 25 75.5.6. 35 25 6 25 khz khz Note : Stresses beyond those isted under Absoute Maximum Ratings may cause permanent damage to the device. Exposure to any Absoute Maximum Rating condition for extended periods may affect device reiabiity and ifetime. Note 2: ESD (Eectrostatic Discharge) sensitive devices. Extensive use of ESD protection devices are used interna to the LT6, however, high eectrostatic discharge can damage or degrade the device. Use proper ESD handing precautions. Note 3: A heat sink may be required to keep the junction temperature beow absoute maximum ratings. Note : The LT6C/LT6I are guaranteed functiona over the operating temperature range of C to 85 C. The LT6H is guaranteed functiona over the operating temperature range of C to 25 C. Note 5: The LT6C is guaranteed to meet specified performance from C to 7 C. The LT6C is designed, characterized and expected to meet specified performance from C to 85 C but is not tested or QA samped at these temperatures. The LT6I is guaranteed to meet specified performance from C to 85 C. The LT6H is guaranteed to meet specified performance from C to 25 C. Note 6: This parameter is not tested. Note 7: Gain error for A = 2.5, 25/ is guaranteed by the other gain error tests. Note 8: Sew rate is measured on the output between 3.5 and 3.5. 6fc 5
LT6 Typica Performance Characteristics INPUT OFFSET OLTAGE (µ) 3 2 2 3 Input Offset otage vs Temperature 9 TYPICAL UNITS = 6. CC = 5 25 5 2 35 5 65 8 95 25 TEMPERATURE ( C) 6 G2 INPUT OFFSET OLTAGE ().5..5.5..5 2. 2.5 3. 3.5 Input Offset otage vs Input otage T A = C T A = 25 C T A = 85 C ENSE = CC = 3 2 3 5 S INPUT OLTAGE () 6 G INPUT OFFSET OLTAGE (µ) 35 3 25 2 5 5 Input Offset otage vs CC Suppy otage T A = 85 C T A = C T A = 25 C ENSE = = 8 5 5 2 25 3 35 CC SUPPLY OLTAGE () 6 G2 OUTPUT OLTAGE ().8.6..2..8.6..2 5 Output otage vs Sense otage Output otage vs Sense otage Gain vs Temperature =. TO 8 CC = 3 A = / T A = C TO 25 C T A = C >.6 T A = C =. 9 3 3 9 5 SENSE OLTAGE ( S S )() OUTPUT OLTAGE () 3.5 3. 2.5 2..5..5 = 6. TO 8 CC = 5 T A = C TO 25 C T A = C > 6.6 T A = C = 6. 6 2 8 2 3 SENSE OLTAGE ( S S ) () GAIN (/) 5.6 5. 5.2 5. 9.98 9.96 9.9 9.92 9.9 7 TYPICAL UNITS ENSE = 5 TO 8 = 6. TO 8 CC = 5 A = 5/ 9.88 25 5 2 35 5 65 8 95 25 TEMPERATURE ( C) 6 G3 6 G 6 G5 NEGATIE SENSE INPUT CURRENT (µa) 2 8 6 2 Negative Sense Input Current vs Sense otage =. TO 8 CC = 3 T A = 25 C T A = 85 C T A = C POSITIE SENSE INPUT CURRENT (µa) 35 3 25 2 5 5 Positive Sense Input Current vs Sense otage =. TO 8 CC = 3 T A = 25 C T A = 85 C T A = C OUTPUT POSITIE SWING () 35 3 25 2 5 5 Output Positive Swing vs Load Current S = 6. CC = 5 ENSE = 5 T A = 25 C A = 5/ T A = 85 C T A = C 7 3 3 7 SENSE OLTAGE ( S S ) () 5 7 3 3 7 SENSE OLTAGE ( S S ) ()..2.3..5.6.7.8.9. LOAD CURRENT (ma) 6 G6 6 G7 6 G8 6 6fc
Typica Performance Characteristics LT6 CC SUPPLY CURRENT (µa) 2 8 6 2 8 6 2 CC Suppy Current vs Input otage ENSE = CC = 3 T A = 25 C T A = 85 C T A = C 2 3 5 TOTAL INPUT OLTAGE () 6 G9 OUTPUT IMPEDANCE (Ω) k k. k Op Amp Output Impedance vs Frequency, S = 6.5 CC = 5 EE = 5 = G2 = 2/ G2 = 5/ G2 = / k k M FREQUENCY (Hz) 6 G23 GAIN () 5 3 2 2 3 5 Gain vs Frequency A = 5 A = k k k M M FREQUENCY (Hz) = 2. CC = 6 G CMRR () 2 8 6 2 CMRR vs Frequency CC PSRR vs Frequency Gain Error vs ENSE = 6. CC = 5 k k k M FREQUENCY (Hz) 6 G CC PSRR () 5 3 9 7 5 3. k k k M FREQUENCY (Hz) = ENSE = CC = 5 6 G2 GAIN ERROR () 2 3 5 5 2 ENSE () = 6. CC = 5 A = / 25 3 6 G2 TOTAL INPUT CURRENT (I S IS ) (na).. Sense Input Current ( CC Powered Down) vs = S T A = 25 C T A = 85 C T A = C. 2 3 5 S () 6 G25 5/DI 5/DI Step Response at ENSE = to 3 = A = / C L = pf 5µs/DI 6 G3 /DI 2/DI Step Response at ENSE = to 3 = A = 5/ C L = pf.2ms/di 6 G 6fc 7
LT6 Typica Performance Characteristics Step Response at ENSE = to Step Response at ENSE = to Step Response at ENSE = to 3 2/DI 2/DI 5/DI 5/DI 2/DI 5/DI = A = / C OUT = pf 5µs/DI 6 G5 = A = 5/ C L = pf 5µs/DI 6 G6 = A = / C OUT = pf 5µs/DI 6 G7 /DI Step Response at ENSE = to 3 2/DI Step Response at ENSE = to 2/DI 5/DI = A = 5/ C L = pf.2ms/di 6 G8 = A = / C L = pf 5µs/DI 6 G9 Step Response at ENSE = to Start-Up Deay 2/DI S 2/DI = A = 5/ C L = pf 5µs/DI 6 G2 CC = 5 ENSE = A = / EE = 2µs/DI 6 G22 8 6fc
LT6 Pin Functions (Pin ): Negative Sense Input Termina. Negative sense votage input wi remain functiona for votages up to 8. is connected to an interna gain-setting resistor R G = 5k. CC (Pin 2): Suppy otage Input. This power suppy pin suppies current to both current sense ampifier and op amp. (Pin 3): Fiter Pin. Connects to an externa capacitor to ro off differentia noise of the system. Poe frequency f 3 = /(2πR C), R = R E R O = 6k. EE (Pin ): Negative Suppy or Ground for Singe Suppy Operation. (Pin 5): otage Output Proportiona to the Magnitude of the Current Fowing Through R SENSE : = A (ENSE ± OS ) OS is the input offset votage. A is the tota gain of the LT6. A2 (Pin 6): Gain Seect Pin. Refer to Tabe. A (Pin 7): Gain Seect Pin. When Pin 7 is shorted to EE, the tota gain is /. When both Pin 6 and Pin 7 are shorted to EE, the tota gain is 5/. When both Pin 6 and Pin 7 are opened, the tota gain is /. S (Pin 8): Positive Sense Input Termina. Connecting a suppy to S and a oad to S wi aow the LT6 to monitor the current through R SENSE, refer to Figure. S is connected to an interna gain setting resistor R G2 = 5k. S remains functiona for votages up to 8. Functiona Diagram LOAD R SENSE IN ( CC.) TO 8 S 8 S R G 5k R G2 5k A R 25k CC 2.7 TO 36 2 O Q R E k A2 5 R O 5k R R/3 EE 3 A2 6 A 7 6 F Figure. Functiona Diagram 6fc 9
LT6 Appications Information The LT6 high side current sense ampifier (Figure ) provides accurate unidirectiona monitoring of current through a user-seected sense resistor. The LT6 features a fuy specified. to 8 input common mode range. A high PSRR CC suppy (2.7 to 36) powers the current sense ampifier and the interna op amp circuitry. The input sense votage is eve shifted from the positive sense power suppy to the ground reference and ampified by a user-seected gain to the output. The buffered output votage is directy proportiona to the current fowing through the sense resistor. Theory of Operation (Refer to Figure ) Current from the source at S fows through R SENSE to the oad at S, creating a sense votage, ENSE. Inputs S and S appy the sense votage to R G2. The opposite ends of resistors R G and R G2 are forced to be at equa potentias by the votage gain of ampifier A. The current through R G2 is forced to fow through transistor Q and is sourced to node O. The current from R G2 fowing through resistor R O gives a votage gain of ten, O /ENSE = R O / R G2 = /. The sense ampifier output at O is ampified again by ampifier A2. The inputs of ampifier A2 can operate to ground which ensures that sma sense votage signas are detected. Ampifier A2 can be programmed to different gains via Pin 6 and Pin 7. Thus, the tota gain of the system becomes A = A2 and = ENSE A. Gain Setting The LT6 gain is set by strapping (or foating) the two gain pins (see Tabe ). This feature aows the user to zoom in by increasing the gain for accurate measurement of ow currents. A = / G2, G2 is the gain of op amp A2. Tabe. Gain Set with Pin 6 and Pin 7 A2 (PIN 6) A (PIN 7) G2 A Open Open EE Out.25 2.5 EE Open 2 2 Out EE 2.5 25 Open EE EE EE 5 5 Seection of Externa Current Sense Resistor Externa R SENSE resistor seection is a deicate trade-off between power dissipation in the resistor and current measurement accuracy. The maximum sense votage may be as arge as ±3 to get maximum dynamic range. For high current appications, the user may want to minimize the sense votage to minimize the power dissipation in the sense resistor. The LT6 s ow input offset votage of 8µ aows for high resoution of ow sense votages. This aows imiting the maximum sense votage whie sti providing high resoution current monitoring. Kevin connection of the LT6 s S and S inputs to the sense resistor shoud be used to provide the highest accuracy in high current appications. Soder connections and PC board interconnect resistance (approximatey.5mω per square) can be a arge error in high current systems. A 5A appication might choose a 2mΩ sense resistor to give a fu-scae input to the LT6. Input offset votage wi imit resoution to ma. Negecting contact resistance at soder joints, even one square of PC board copper at each resistor end wi cause an error of 5. This error wi grow proportionatey higher as monitored current eves rise. 6fc
Appications Information Noise Fitering The LT6 provides signa fitering via pin that is internay connected to the resistors R E and R O. This pin may be used to fiter the input signa entering the LT6 s interna op amp, and shoud be used when fast rippe current or transients fow through the sense resistor. High frequency signas above the 3kHz bandwidth of the LT6 s interna ampifier wi cause errors. A capacitor connected between and EE creates a singe poe ow pass fiter with corner frequency: f 3 = /(2πR C) where R = 6k. A 22pF capacitor creates a poe at 2kHz, a good choice for many appications. Output Signa Range The LT6 s output signa is deveoped by current through R G2 into output resistor R O. The current is ENSE /R G2. The sense ampifier output, O, is buffered by the interna op amp so that connecting the output pins to other systems wi preserve signa accuracy. For zero ENSE, interna circuit saturation with oss of accuracy occurs at the minimum swing, 5 above EE. may swing positive to within 75 of CC or a maximum of 36, a imit set by interna junction breakdown. Within these constraints, LT6 an ampified, eve shifted representation of the R SENSE votage is deveoped at. The output is we behaved driving capacitive oads to pf. Sense Input Signa Range The LT6 has high CMRR over the wide input votage range of. to 8. The minimum operation votage of the sense ampifier input is. above CC. The output remains accurate even when the sense inputs are driven to 8. Figure 2 shows that OS changes very sighty over a wide input range. Furthermore, the sense inputs S and S can coapse to zero vots without incurring any damage to the device. The LT6 can hande differentia sense votages up to the votage of the sense inputs suppies. For exampe, S = 8 and S = can be a vaid condition in a current monitoring appication (Figure 3) when an overoad protection fuse is bown and S votage coapses to ground. Under this condition, the output of the LT6 goes to the positive rai, OH. There is no phase inversion to cause an erroneous output signa. For the opposite case when S coapse to ground with S hed up at some higher votage potentia, the output wi sit at OL. If both inputs fa beow the minimum CM votage, CC., the output is indeterminate but the LT6 wi not be damaged. INPUT OFFSET OLTAGE ().5..5.5..5 2. 2.5 ENSE = CC = 3 5 TO LOAD C2.µF 2 CC 3 R SENSE FUSE 8 S A A2 7 6 DC SOURCE C.µF 3. 3.5 2 3 5 INPUT OLTAGE () EE LT6 OUT 5 6 F3 OUTPUT 6 F2 Figure 2. OS vs Input otage Figure 3. Current Monitoring of a Fuse Protected Circuit 6fc
LT6 Appications Information Low Sense otage Operation Figure shows the simpest circuit configuration in which the LT6 may be used. Whie (output votage) increases with positive sense current, at ENSE =, the LT6 s buffered output can ony swing as ow as OL = 5. The accuracy at sma sense votages can be improved by seecting higher gain. When gain of 5/ is seected, as shown in Figure 7, eaves the cipped region for a positive ENSE greater than compared to 2.5 for gain of / (see Figure 6). 3 TO LOAD 2 CC C2.µF 3 R SENSE S 8 S A A2 7 6 C.µF 5 OUTPUT OLTAGE ().6..2..8.6. =. TO 8 CC = 3 A = /.2 EE LT6 OUT 6 F 5 OUTPUT 3 6 9 2 5 SENSE OLTAGE ( S S ) () 6 F5 Figure. LT6 Load Current Monitor Figure 5. Output otage vs ENSE OUTPUT OLTAGE ()..35.3.25.2.5..5 =. TO 8 CC = 3 A = / 5 5 2 25 SENSE OLTAGE ( S S ) () 3 6 F6 OUTPUT OLTAGE ().8.6..2..8.6..2 =. TO 8 CC = 3 A = 5/ 5 5 2 25 3 SENSE OLTAGE ( S S ) () 6 F7 Figure 6. Expanded iew of Output otage vs ENSE, A = / Figure 7. Expanded iew of Output otage vs ENSE, A = 5/ 2 6fc
LT6 Appications Information Power Down Whie Connected to a Battery Another unique benefit of the LT6 is that you can eave it connected to a battery even when it is denied power. When the LT6 oses power or is intentionay powered down, its inputs remain high impedance (see Figure 8). This is due to the impementation of Linear Technoogy s Over- The-Top input topoogy at its front end. When powered down, the LT6 inputs draw ess than µa of current. TO LOAD LT6 R SENSE I SENSE BATTERY. TO 8 3 POWER DOWN OK CC INPUTS REMAIN Hi-Z CC EE A2 A 6 F8 Figure 8. Input Remains Hi-Z when LT6 is Powered Down Typica Appication Adjust Gain Dynamicay for Enhanced Range Micro-Hotpate otage and Current Monitor TO LOAD R SENSE I SENSE FROM SOURCE DR LT6 Ω 5 CC EE A2 2N72 A 6 TA5 (GAIN = ) 5 (GAIN = 5) I HOTPLATE MICRO-HOTPLATE BOSTON MICROSYSTEMS MHPS-5 5 5 CC LT6 EE A2 A 5 M9 M3 M LT99 P P3 P9 CURRENT MONITOR = 5/mA OLTAGE MONITOR = DR DR DR 6 TA6 www.bostonmicrosystems.com 6fc 3
LT6 Package Description Pease refer to http://www.inear.com/designtoos/packaging/ for the most recent package drawings. DD Package 8-Lead Pastic DFN (3mm 3mm) (Reference LTC DWG # 5-8-698 Rev C).7 ±.5 R =.25 TYP 5 8. ±. 3.5 ±.5 2. ±.5.65 ±.5 (2 SIDES) PACKAGE OUTLINE.25 ±.5.5 BSC 2.38 ±.5 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN TOP MARK (NOTE 6).2 REF 3. ±. ( SIDES).75 ±.5..5.65 ±. (2 SIDES).25 ±.5.5 BSC 2.38 ±. BOTTOM IEW EXPOSED PAD NOTE:. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M-229 ARIATION OF (WEED-) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED.5mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN LOCATION ON TOP AND BOTTOM OF PACKAGE (DD8) DFN 59 RE C MS8 Package 8-Lead Pastic MSOP (Reference LTC DWG # 5-8-66 Rev F).889 ±.27 (.35 ±.5) 5.23 (.26) MIN 3.2 3.5 (.26.36).2 ±.38 (.65 ±.5) TYP GAUGE PLANE.8 (.7).25 (.) DETAIL A.65 (.256) BSC RECOMMENDED SOLDER PAD LAYOUT NOTE:. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 6 TYP.53 ±.52 (.2 ±.6) DETAIL A SEATING PLANE 3. ±.2 (.8 ±.) (NOTE 3).9 ±.52 (.93 ±.6). (.3) MAX.22.38 (.9.5) TYP.65 (.256) BSC 8 7 6 5 2 3 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED.52mm (.6") PER SIDE. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED.52mm (.6") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE.2mm (.") MAX.52 (.25) REF 3. ±.2 (.8 ±.) (NOTE ).86 (.3) REF.6 ±.58 (. ±.2) MSOP (MS8) 37 RE F 6fc
LT6 Revision History (Revision history begins at Rev C) RE DATE DESCRIPTION PAGE NUMBER C /2 Corrected vaue in Output Signa Range section. Information furnished by Linear Technoogy Corporation is beieved to be accurate and reiabe. However, no responsibiity is assumed for its use. Linear Technoogy Corporation makes no representation that the interconnection of its circuits as described herein wi not infringe on existing patent rights. 6fc 5
LT6 Typica Appications 8mA/A White LED Current Reguator IN 3.3 TO.2 SINGLE Li-Ion LED ON IN W LT336 SHDN GND L 3µH C FB LED CURRENT D B3 2k D2 LED.3Ω 22µF 6 CER 2 WARNING! ERY BRIGHT DO NOT OBSERE DIRECTLY LT6 S CC.7µF 6.3 CER 8.2k.µF MMBT2222.99k EE A A2 OPEN: A CLOSED: 8mA D: DIODES INC. D2: LUMILEDS LXML-PW9 WHITE EMITTER L: SUMIDA CDRH6D28-3R 6 TA2 Fitered Gain of 2 Current Sense Gain of 5 Current Sense UPPLY. TO 8 I SENSE R SENSE LT6 S LOAD UPPLY 6. TO 8 I SENSE R SENSE LT6 S LOAD 3 CC 5 CC pf EE A2 A 6 TA3 2 R SENSE I SENSE EE A2 A 6 TA 5 R SENSE I SENSE 3 AT 2.6kHz Reated Parts PART NUMBER DESCRIPTION COMMENTS LTC3 Dua Precision Instrumentation Switched Capacitor Buiding Bock 2 CMRR, 3 to 8 Operation LT9/LT9 Dua and Quad Micropower Rai-to-Rai Input and Output Op Amps 5µA Ampifier, 2.7 to Operation, Over-The-Top Inputs LT62/LT62 Rai-to-Rai Current Sense Ampifiers Accurate Output Current Programming, Battery Charging to 32 LT787 Precision Bidirectiona, High Side Current Sense Ampifier 75µ OS, 6, 6µA Operation LTC6/LTC6H High otage, High Side, Precision Current Sense Ampifiers to 6/5 to, Gain Configurabe, SOT-23 6 LT 2 RE C PRINTED IN USA Linear Technoogy Corporation 63 McCarthy Bvd., Mipitas, CA 9535-77 (8) 32-9 FAX: (8) 3-57 www.inear.com LINEAR TECHNOLOGY CORPORATION 25 6fc