LT1310 LINER [Linear Technology], LT1310 Datasheet
LT1310
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LT1310 Summary of contents
Page 1
... Intended for use in applications where switching frequency must be accu- rately controlled, the LT1310 can generate 12V 400mA from a 5V input. Switching frequency is set with an external capacitor, and the device can be operated in either free-running or phase- locked mode ...
Page 2
... SHDN = Low Switch Off 3. 2.4V SHDN Active Mode Shutdown Mode Note 2: The LT1310E is guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, chacterization and correlation with statistical process controls ORDER PART ...
Page 3
... G05 Oscillator Frequency 47pF Capacitor on C Pin T 3800 PLL-LPF = HIGH 3500 3200 2900 2600 2300 2000 – 100 –25 TEMPERATURE ( C) 1310 G08 LT1310 Undervoltage Lockout 2.80 2.75 2.70 2.65 2.60 2.55 2.50 – 100 –25 TEMPERATURE ( C) 1310 G03 Oscillator Frequency vs Feedback Voltage 1400 220pF C ...
Page 4
... Capacitor on C Pin T 3500 MAXIMUM 3000 2500 2000 MINIMUM 1500 1000 500 100 –50 – TEMPERATURE ( C) CESAT 0.5 1.0 1.5 SWITCH CURRENT (A) 1310 G15 Start-Up Response V OUT 5V/DIV I L 1A/DIV V SHDN NO SYNC SIGNAL 20 s/DIV LT1310 G17 f = 1.2MHz 75 100 1310 G12 LT1310 G18 1310f ...
Page 5
... Multiple vias (local ground plane ground backplane) placed close to the exposed pad can further aid in reducing thermal resistance. The exposed pad must be soldered to ground for the LT1310 to function properly. SW (Pins 6, 7): Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to keep EMI down. ...
Page 6
... OUT The LT1310 is phase lockable up to 4.5MHz, giving the pin either C user precise control over switching frequency. The phase detector compares the incoming sync signal to the internal oscillator signal ...
Page 7
... C 330pF 1500pF 2700pF 10k 180pF 1000pF 2200pF 10k 100pF 820pF 1500pF 15k 68pF 820pF 1500pF 15k 47pF 330pF 1500pF 20k 33pF 330pF 1000pF 20k L1 C1 LT1310 178k 4 CERAMIC IN SHDN FB SYNC 20.5k PLL-LPF GND Figure 2b. Circuit Used for C ...
Page 8
... Ceramic capacitors also make a good choice for the input decoupling capacitor, which should be placed as close as possible to the LT1310 4.7 F input capacitor is sufficient for most applications. Table 3 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts ...
Page 9
... Compensation—Theory Like all other current mode switching regulators, the LT1310 needs to be compensated for stable and efficient operation. Two feedback loops are used in the LT1310 fast current loop which does not require compensation, and a slower voltage loop which does. Standard Bode plot analysis can be used to understand and adjust the voltage feedback loop ...
Page 10
... Application Specific Not Adjustable Adjustable Adjustable Diode Selection Application Specific A Schottky diode is recommended for use with the LT1310. Application Specific The Microsemi UPS120 is a very good choice. Where the Not Adjustable input to output voltage differential exceeds 20V, use the Not Adjustable UPS140 (a 40V diode) ...
Page 11
... U APPLICATIO S I FOR ATIO Layout Hints The high speed operation of the LT1310 demands careful attention to board layout. You will not get advertised Figure 6. Recommended Component Placement for Boost Converter. Note Direct High Current Paths Using Wide PC Traces. Minimize Trace Area at Pin Pin and Pin 1 (FB) ...
Page 12
... LT1310 U TYPICAL APPLICATIO 3MHz 5V to 12V Converter L1 3 LT1310 C1 2 SHUTDOWN SHDN FB SYNC IN SYNC PLL-LPF C T 3MHz V GND 3.01k 10k 1000pF 680pF C1, C2: TAIYO YUDEN LMK212BJ225MG D1: MOTOROLA MBRM120 L1: PANASONIC ELL6RH2R7M *EXPOSED PAD MUST ALSO BE GROUNDED ...