Datasheet Linear Technology LT1613 (Linear Technology) - 7
| Manufacturer | Linear Technology |
| Description | 1.4MHz, Single Cell DC/DC Converter in 5-Lead SOT-23 |
| Pages / Page | 12 / 7 — OPERATIO. Figure 5. 2.5V to 5V Boost Converter with “A” Case Size … |
| Revision | S |
| File Format / Size | PDF / 302 Kb |
| Document Language | English |
OPERATIO. Figure 5. 2.5V to 5V Boost Converter with “A” Case Size Tantalum Input and Output Capacitors
Model Line for this Datasheet
Text Version of Document
LT1613
U OPERATIO
effect on loop stability, as long as minimum capacitance resulting in a severely underdamped response. By adding requirements are met). The transient response to a load R3 and CPL as detailed in Figure 8’s schematic, phase step of 50mA to 100mA is pictured in Figure 6. Note the margin is restored, and transient response to the same “double trace,” due to the ESR of C2. The loop is stable and load step is pictured in Figure 9. R3 isolates the device FB settles in less than 100µs. In Figure 7, C2 is replaced by a pin from fast edges on the VOUT node due to parasitic PC 10µF ceramic unit. Phase margin decreases drastically, trace inductance. Figure 10’s circuit details a 5V to 12V boost converter, L1 10µH D1 delivering up to 130mA. The transient response to a load V V IN OUT 2.5V 5V step of 10mA to 130mA, without CPL, is pictured in + C1 V SW Figure␣ 11. Although the ringing is less than that of the IN R1 15µF 37.4k previous example, the response is still underdamped and LT1613 + C2 22µF can be improved. After adding R3 and CPL, the improved SHDN SHDN FB transient response is detailed in Figure 12. GND R2 12.1k Figure 13 shows a SEPIC design, converting a 3V to 10V input to a 5V output. The transient response to a load step C1: AVX TAJA156M010R C2: AVX TAJA226M006R of 20mA to 120mA, without CPL and R3, is pictured in D1: MOTOROLA MBR0520 1613 F05 L1: MURATA LQH3C100 Figure␣ 14. After adding these two components, the im- proved response is shown in Figure 15.
Figure 5. 2.5V to 5V Boost Converter with “A” Case Size Tantalum Input and Output Capacitors
L1 10µH D1 V V IN OUT 2.5V 5V CPL + C1 VIN SW 330pF 15µF VOUT R1 LT1613 20mV/DIV R3 37.4k C2 10k 10µF AC COUPLED SHUTDOWN SHDN FB GND R2 12.1k 100mA LOAD CURRENT 50mA C1: AVX TAJA156M010R C2: TAIYO YUDEN LMK325BJ106MN 200µs/DIV 1613 F06 D1: MBR0520 1613 F08 L1: MURATA LQH3C100K04
Figure 6. 2.5V to 5V Boost Converter Transient Response with 22
µ
F Tantalum Output Capacitor. Figure 8. 2.5V to 5V Boost Converter with Ceramic Apparent Double Trace on VOUT Is Due to Switching Output Capacitor. CPL Added to Increase Phase Margin, Frequency Ripple Current Across Capacitor ESR R3 Isolates FB Pin from Fast Edges
V V OUT OUT 20mV/DIV 20mV/DIV AC COUPLED AC COUPLED 100mA 100mA LOAD CURRENT LOAD CURRENT 50mA 50mA 200µs/DIV 1613 F07 200µs/DIV 1613 F09
Figure 7. 2.5V to 5V Boost Converter with Figure 9. 2.5V to 5V Boost Converter with 10
µ
F Ceramic 10
µ
F Ceramic Output Capacitor, No CPL Output Capacitor, 330pF CPL and 10k in Series with FB Pin
7
U OPERATIO
effect on loop stability, as long as minimum capacitance resulting in a severely underdamped response. By adding requirements are met). The transient response to a load R3 and CPL as detailed in Figure 8’s schematic, phase step of 50mA to 100mA is pictured in Figure 6. Note the margin is restored, and transient response to the same “double trace,” due to the ESR of C2. The loop is stable and load step is pictured in Figure 9. R3 isolates the device FB settles in less than 100µs. In Figure 7, C2 is replaced by a pin from fast edges on the VOUT node due to parasitic PC 10µF ceramic unit. Phase margin decreases drastically, trace inductance. Figure 10’s circuit details a 5V to 12V boost converter, L1 10µH D1 delivering up to 130mA. The transient response to a load V V IN OUT 2.5V 5V step of 10mA to 130mA, without CPL, is pictured in + C1 V SW Figure␣ 11. Although the ringing is less than that of the IN R1 15µF 37.4k previous example, the response is still underdamped and LT1613 + C2 22µF can be improved. After adding R3 and CPL, the improved SHDN SHDN FB transient response is detailed in Figure 12. GND R2 12.1k Figure 13 shows a SEPIC design, converting a 3V to 10V input to a 5V output. The transient response to a load step C1: AVX TAJA156M010R C2: AVX TAJA226M006R of 20mA to 120mA, without CPL and R3, is pictured in D1: MOTOROLA MBR0520 1613 F05 L1: MURATA LQH3C100 Figure␣ 14. After adding these two components, the im- proved response is shown in Figure 15.
Figure 5. 2.5V to 5V Boost Converter with “A” Case Size Tantalum Input and Output Capacitors
L1 10µH D1 V V IN OUT 2.5V 5V CPL + C1 VIN SW 330pF 15µF VOUT R1 LT1613 20mV/DIV R3 37.4k C2 10k 10µF AC COUPLED SHUTDOWN SHDN FB GND R2 12.1k 100mA LOAD CURRENT 50mA C1: AVX TAJA156M010R C2: TAIYO YUDEN LMK325BJ106MN 200µs/DIV 1613 F06 D1: MBR0520 1613 F08 L1: MURATA LQH3C100K04
Figure 6. 2.5V to 5V Boost Converter Transient Response with 22
µ
F Tantalum Output Capacitor. Figure 8. 2.5V to 5V Boost Converter with Ceramic Apparent Double Trace on VOUT Is Due to Switching Output Capacitor. CPL Added to Increase Phase Margin, Frequency Ripple Current Across Capacitor ESR R3 Isolates FB Pin from Fast Edges
V V OUT OUT 20mV/DIV 20mV/DIV AC COUPLED AC COUPLED 100mA 100mA LOAD CURRENT LOAD CURRENT 50mA 50mA 200µs/DIV 1613 F07 200µs/DIV 1613 F09
Figure 7. 2.5V to 5V Boost Converter with Figure 9. 2.5V to 5V Boost Converter with 10
µ
F Ceramic 10
µ
F Ceramic Output Capacitor, No CPL Output Capacitor, 330pF CPL and 10k in Series with FB Pin
7
