LT1302 Linear Technology Corporation, LT1302 Datasheet
LT1302
Available stocks
Related parts for LT1302
LT1302 Summary of contents
Page 1
... Quiescent current is just 200 A and can be further reduced shutdown. Available in 8-pin PDIP or 8-pin SO packaging, the LT1302/ LT1302-5 have the highest switch current rating of any similarly packaged switching regulators presently on the market. ...
Page 2
... SHDN SHDN SHDN Note 2: The LT1302 operates in a variable frequency mode. Switching frequency depends on load inductance and operating conditions and may be above specified limits. Note 3: Minimum switch current 100% tested. Maximum switch current guaranteed by design TOP VIEW ...
Page 3
... TEMPERATURE ( C) 1302 G07 Switch Saturation Voltage 600 500 400 300 200 100 5.0 SWITCH CURRENT (A) LT1302-5 Sense Pin Resistance 600 500 400 300 200 100 0 100 –50 – TEMPERATURE ( C) LT1302-5 Output Voltage 5.100 5.075 5.050 5.025 5 ...
Page 4
... G13 * APPROXIMATE I (Pin 5): Normally left floating. Addition of a 3.3k resistor T should be connected to GND forces the LT1302 into current mode at light loads. Efficiency drops at light load but increases at medium loads. See Applications Information section. V (Pin 6): Supply Pin. Must be bypassed with: ( ceramic to GND, and (2) a large value electrolytic to PGND ...
Page 5
... IN A2 CMP1 + OFF ENABLE 220kHz OSCILLATOR – HYSTERETIC COMPARATOR 15mV – ERROR AMPLIFIER 22k C4 0.01 F Figure 2. LT1302 Block Diagram LT1302/LT1302 36mV R4 + 1.75 R5 730 – 160X DRIVER BIAS 300 3.6k I PGND OUT + ...
Page 6
... GND U OPERATIO The LT1302’s operation can best be understood by examining the block diagram in Figure 2. The LT1302 operates in one of two modes, depending on load. With light loads, comparator CMP1 controls the output; with heavy loads, control is passed to error amplifier A1. Burst Mode operation consists of monitoring the FB pin voltage with hysteretic comparator CMP1 ...
Page 7
... OUT A special situation exists where the V high, such as a 2V-to-12V converter. The required duty cycle is higher than the LT1302 can provide, so the converter must be designed for discontinuous operation. This means that inductor current goes to zero during the switch off-time. In the 2V-to-12V case, inductance must be low enough so that current in the inductor can reach single cycle ...
Page 8
... W U Input Capacitor The input supply should be decoupled with a good quality electrolytic capacitor close to the LT1302 to provide a stable input supply. Long leads or traces from power source to the switcher can have considerable impedance and contains P-P at the LT1302’s switching frequency. The input capacitor provides a low impedance at high frequency ...
Page 9
... C Low Frequency Components Under Load W U behavior in the 4th graticule is the result of the LT1302’s Burst Mode comparator turning off all switching as output voltage rises above its threshold. In Figure 7c, the 0.1 F capacitor has been replaced by a 0.01 F unit. Undershoot is less but the response is still underdamped ...
Page 10
... Pin T The I pin is used to disable Burst Mode, forcing the T LT1302 to operate in current mode even at light load. To disable Burst Mode, 3.3k resistor R1 is connected from I to gound. More conservative frequency compensation must be used when in this mode. A 0.1 F capacitor and 4.7k resistor from V 1302 F07c adequate ...
Page 11
... R1 and R2 should be close to the feedback pin (pin4). Noise can easily be coupled into this pin if care is not taken. A small capacitor (100pF to 200pF) from FB to ground provides a high frequency bypass. If the LT1302 is oper- ated off a three-cell or higher input series with V from noise spikes on the input supply ...
Page 12
... Pins 1 and 8 attached to topside copper N8 Package, 8-Lead DIP: Thermal Resistance (Junction-to-Ambient) = 100 C/W Calculating Temperature Rise Power dissipation internal to the LT1302 in a boost regulator configuration is approximately equal to OUT I V OUT The first term in this equation is due to switch “ ...
Page 13
... U U APPLICATIONS INFORMATION As an example, consider a boost converter with the following specifications OUT I = 700mA OUT Total power loss in the LT1302, assuming R = 0.15 and V = 0.45V, is 700 223 312 mW Using the CS8 package with 100 sq. mm topside and backside heat sinking (312mW)(84 C/ ...
Page 14
... AVX TPSD107M010R0100 C2 = AVX TPSD336M025R0200 R1 301k 1% 2N3906 (169k FOR 3.3V) 100k SHDN FB 56. GND 100pF 4.99k 20k 1% 0.01 F 36.5k 1% 1302 TA03 SHDN SHUTDOWN 100k 866k 100pF 20k 0.02 F LT1302 • TA04 D1 = MOTOROLA MBRS130LT3 L1 = COILCRAFT DO3316-332 ...
Page 15
... Li-Ion Cell to 5.8V/600mA DC/DC Converter C2 220 F L1 10V LT1302 SHDN V C GND PGND 20k SHUTDOWN 10nF DUTY CYCLE = PEAK SWITCH VOLTAGE = V LT1302/LT1302-5 13V IN OUT + 22 F 330k 25V LT1121 1% SHDN ADJ GND 150k 1% 3.3V OUTPUT 400mA L2 MBRS130LT3 22 H 365k V 1% OUT 5.8V 600mA + ...
Page 16
... LT1302/LT1302-5 PACKAGE DESCRIPTION 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) +0.025 0.325 –0.015 +0.635 8.255 –0.381 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTURSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm). 0.010 – 0.020 45 (0.254 – ...