LTC1261CS Linear Technology, LTC1261CS Datasheet
LTC1261CS
Specifications of LTC1261CS
Available stocks
Related parts for LTC1261CS
LTC1261CS Summary of contents
Page 1
... The LTC1261CS operates from a single supply and provides an adjustable output voltage from –1.25V to – 8V. An on-chip resistor string allows the LTC1261CS to be configured for output volt- ages of – 3.5V, – 4V, – 4.5V or – 5V with no external components. The LTC1261CS8 is optimized for applica- tions which use higher supply or which require low output voltages ...
Page 2
... OUT LTC1261CS8-4.5 ADJ (COMP PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO 1261 *FOR FIXED VERSIONS 12614 = 150 C, = 150 C/W JA 126145 ORDER PART TOP VIEW NUMBER SHDN LTC1261CS 3 12 REG 4 11 OUT 5 10 ADJ ADJ PACKAGE 14-LEAD PLASTIC SO = 150 C, = 110 C unless otherwise specified – ...
Page 3
... LTC1261CS8 cannot be CC OUT CC connected in tripler mode) with C1 connected between C1 + – C2 connected between C2 and implies doubler mode where V – for the LTC1261CS this means C1 connects from C1 CC OUT CC = 3.3 F unless otherwise specified. OUT – 4V 8mA OUT OUT – 4V 7mA OUT OUT – ...
Page 4
... V = –4V OUT 1000 900 DOUBLER MODE 800 V 700 CC TRIPLER MODE 600 500 –40 – TEMPERATURE (˚C) Tripler Mode ADJ 3 9 – ADJ LTC1261CS – –4V 5% OUT OUT GND 3 LTC1261 • TC02 7 LTC1261 • TPC03 = 3.3V 80 100 LTC1261 • TPC06 ...
Page 5
... C2 (Pin 4/NA): C2 Positive Input. In tripler mode con- + nect a 0.1 F capacitor from with the LTC1261CS in tripler mode only; in doubler mode this pin should float. – C2 (Pin 5/NA): C2 Negative Input. In tripler mode connect a 0.1 F capacitor from C2 mode connect a 0.1 F capacitor from C1 GND (Pin 6/Pin 4): Ground ...
Page 6
... C1 and C2 pins. C1 floating (Figure 1b). Tripler Mode The LTC1261CS can be used in a tripler mode which can generate negative output voltages up to twice the supply voltage. The total voltage between the V can three times V . For example, tripler mode can S be used to generate – 5V from a single positive 3.3V supply ...
Page 7
... REG output will stay low. LTC1261 OUT + C OUT 124k R * ADJ 226k R1* INTERNALLY 100k CONNECTED FOR R0* FIXED OUTPUT VOLTAGE PARTS 50k ADJ/COMP REG *LTC1261CS14 ONLY LTC1261 • F02 and 8mA with the drain can be pulled above V CC without 7 ...
Page 8
LTC1261 U U APPLICATIONS INFORMATION OUTPUT RIPPLE Output ripple in the LTC1261 comes from two sources; voltage droop at the output capacitor between clocks and frequency response of the regulation loop. Voltage droop is easy to calculate. With a typical ...
Page 9
... U U APPLICATIONS INFORMATION OUT 0.1 F LTC1261CS8 – C1 COMP + GND 100pF 4 Figure 4. Output Filter Cuts Ripple Below 3mV CAPACITOR SELECTION Capacitor Sizing The performance of the LTC1261 can be affected by the capacitors it is connected to. The LTC1261 requires by- pass capacitors to ground for both the V The input capacitor provides most of LTC1261’s supply current while it is charging the flying capacitors ...
Page 10
... The LTC1261 uses a positive OUT , not a negative reference OUT 6 (4*) GND R1 LTC1261 10 (5*) ADJ –1.24V OUT OUT R2 *LTC1261CS8 LTC1261 • F06 Figure 6. External Resistor Connections ...
Page 11
... The LTC1261 can be internally configured with nonstand- ard fixed output voltages. Contact the Linear Technology Marketing Department for details. N 3.3V Input, – 4.5V Output GaAs FET Bias Generator ...
Page 12
LTC1261 U TYPICAL APPLICATIONS V BAT SHUTDOWN 0 8.4V BAT (7 NiCd CELLS) SHUTDOWN 1 F 0.1 F 1mV Ripple, 5V Input, – 4V Output GaAs FET Bias Generator V BAT SHUTDOWN 5V 1 ...
Page 13
U TYPICAL APPLICATIONS High Supply Voltage, – 5V Output GaAs FET Bias Generator 8V V 12V BAT SHUTDOWN 0.1 F 0.1 F Low Output Voltage Generator 100pF ADJ 0.1 F ...
Page 14
... LTC1261 U TYPICAL APPLICATIONS This circuit uses the LTC1261CS8 to generate a – 1.24V output at 20mA. Attached to this output is a 312 resistor to make the current/voltage conversion. 4mA through 312 generates 1.24V, giving a net 0V output. 20mA through 312 gives 6.24V across the resistor, giving a net 5V output ...
Page 15
... FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 16
... GaAs FET Bias with Linear Regulator 1mV Ripple GaAs FET Bias 0.4V Dropout Voltage at 150mA, Low Noise, Switched Capacitor Regulated Voltage Inverter –0.5V BIAS 5.5% GaAs TRANSMITTER 3.3 F LTC1261 • TA08 1261fa LT/TP 0198 REV A 4K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1994 ...