Datasheet EL7515 (Renesas) - 6
| Fabricante | Renesas |
| Descripción | High Frequency PWM Step-Up Regulator |
| Páginas / Página | 9 / 6 — Typical Performance Curves. (Continued). IN = 5V, VO = 12V, IO = 30mA. IN … |
| Formato / tamaño de archivo | PDF / 564 Kb |
| Idioma del documento | Inglés |
Typical Performance Curves. (Continued). IN = 5V, VO = 12V, IO = 30mA. IN = 5V, VO = 12V, IO = 300mA. 50mV/DIV. VLX. 10V/DIV
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EL7515
Typical Performance Curves (Continued) V V IN = 5V, VO = 12V, IO = 30mA IN = 5V, VO = 12V, IO = 300mA
V
V 50mV/DIV IN 50mV/DIV IN VLX 10V/DIV 10V/DIV VLX 20mV/DIV
V V O O 20mV/DIV IL I 0.5A/DIV L 0.5A/DIV 0.5µs/DIV 0.5µs/DIV FIGURE 7. STEADY STATE OPERATION (INDUCTOR FIGURE 8. STEADY STATE OPERATION (INDUCTOR DISCONTINUOUS CONDUCTION) CONTINUOUS CONDUCTION) VIN = 5V, VO = 12V, IO = 300mA VIN = 5V, VO = 12V, IO = 50mA TO 300mA 2V/DIV 5V/DIV IO 100mA/DIV
VIN VO
VO 0.5V/DIV 0.5A/DIV IL 0.5ms/DIV 0.2ms/DIV FIGURE 9. POWER-UP FIGURE 10. LOAD TRANSIENT RESPONSE Applications Information
The EL7515 is a step-up regulator, operated at fixed capacitor. This in turn controls the rising rate of the output frequency pulse-width-modulation (PWM) control. The input voltage. voltage is 1.8V to 13.2V and output voltage is 4.5V to 17V. The regulator goes through the start-up sequence as well The switching frequency (up to 1.2MHz) is decided by the after the EN signal is pulled to HI. resistor connected to RT pin.
Steady-State Operation Start-Up
When the output reaches the preset voltage, the regulator After VDD reaches a threshold of about 1.7V, the start-up operates at steady state. Depending on the input/output oscillator generates fixed duty-ratio of 0.5 to 0.7 at a conditions and component values, the inductor operates at frequency of several hundred kilohertz. This will boost the either continuous-conduction mode or output voltage. discontinuous-conduction mode. When VDD reaches about 3.7V, the PWM comparator takes In the continuous-conduction mode, the inductor current is a over the control. The duty ratio will be decided by the triangular waveform and LX voltage a pulse waveform. In the multiple-input direct summing comparator, Max_Duty signal discontinuous-conduction mode, the inductor current is (about 90% duty-ratio), and the Current Limit Comparator, completely dried out before the MOSFET is turned on again. whichever is the smallest. The input voltage source, the inductor, and the MOSFET and The soft-start is provided by the current limit comparator. As output diode parasitic capacitors form a resonant circuit. the internal 12µA current source charges the external CSS, Oscillation will occur in this period. This oscillation is normal the peak MOSFET current is limited by the voltage on the and will not affect the regulation. FN7120 Rev 2.00 Page 6 of 9 August 10, 2007
Typical Performance Curves (Continued) V V IN = 5V, VO = 12V, IO = 30mA IN = 5V, VO = 12V, IO = 300mA
V
V 50mV/DIV IN 50mV/DIV IN VLX 10V/DIV 10V/DIV VLX 20mV/DIV
V V O O 20mV/DIV IL I 0.5A/DIV L 0.5A/DIV 0.5µs/DIV 0.5µs/DIV FIGURE 7. STEADY STATE OPERATION (INDUCTOR FIGURE 8. STEADY STATE OPERATION (INDUCTOR DISCONTINUOUS CONDUCTION) CONTINUOUS CONDUCTION) VIN = 5V, VO = 12V, IO = 300mA VIN = 5V, VO = 12V, IO = 50mA TO 300mA 2V/DIV 5V/DIV IO 100mA/DIV
VIN VO
VO 0.5V/DIV 0.5A/DIV IL 0.5ms/DIV 0.2ms/DIV FIGURE 9. POWER-UP FIGURE 10. LOAD TRANSIENT RESPONSE Applications Information
The EL7515 is a step-up regulator, operated at fixed capacitor. This in turn controls the rising rate of the output frequency pulse-width-modulation (PWM) control. The input voltage. voltage is 1.8V to 13.2V and output voltage is 4.5V to 17V. The regulator goes through the start-up sequence as well The switching frequency (up to 1.2MHz) is decided by the after the EN signal is pulled to HI. resistor connected to RT pin.
Steady-State Operation Start-Up
When the output reaches the preset voltage, the regulator After VDD reaches a threshold of about 1.7V, the start-up operates at steady state. Depending on the input/output oscillator generates fixed duty-ratio of 0.5 to 0.7 at a conditions and component values, the inductor operates at frequency of several hundred kilohertz. This will boost the either continuous-conduction mode or output voltage. discontinuous-conduction mode. When VDD reaches about 3.7V, the PWM comparator takes In the continuous-conduction mode, the inductor current is a over the control. The duty ratio will be decided by the triangular waveform and LX voltage a pulse waveform. In the multiple-input direct summing comparator, Max_Duty signal discontinuous-conduction mode, the inductor current is (about 90% duty-ratio), and the Current Limit Comparator, completely dried out before the MOSFET is turned on again. whichever is the smallest. The input voltage source, the inductor, and the MOSFET and The soft-start is provided by the current limit comparator. As output diode parasitic capacitors form a resonant circuit. the internal 12µA current source charges the external CSS, Oscillation will occur in this period. This oscillation is normal the peak MOSFET current is limited by the voltage on the and will not affect the regulation. FN7120 Rev 2.00 Page 6 of 9 August 10, 2007