ST2S08B STMicroelectronics, ST2S08B Datasheet - Page 10

• Manufacturer Part Number: ST2S08B
• Description: Dual synchronous rectification, 1.5 A, 1.5 MHz adjustable step-down switching regulator
• Manufacturer: STMicroelectronics

Specifications of ST2S08B

• Typical Efficiency: > 80 % at VOUT= 1.2 V
• Non-switching Quiescent Current: max 1 mA over temperature range

General information
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General information
The ST2S08B is a dual adjustable current mode PWM step-down DC-DC converter.
It is a complete 1.5 A switching regulator with internal compensation that eliminates the
need for additional components.
The constant frequency, current mode, PWM architecture and stable operation with ceramic
capacitors, results in low, predictable output ripple.
To clamp the error amplifier reference voltage, a soft-start control block, generating a
voltage ramp, has been implemented. Other circuits fitted to the device protection are the
thermal shut-down block, which turns off the regulator when the junction temperature
exceeds 150 °C (typ.), and cycle-by-cycle switching current limiting.
Operation of the device requires few components: 2 inductors, 3 capacitors, and a resistor
divider. The chosen inductor must be capable of not saturating at the peak current level. Its
value should be selected keeping in mind that a large inductor value increases the efficiency
at low output current and reduces output voltage ripple, while a smaller inductor can be
chosen when it is important to reduce package size and total application cost.
Finally, the ST2S08 has been designed to work properly with X5R or X7R SMD ceramic
capacitors both at input and at output. These types of capacitors, due to their very low series
resistance (ESR), minimize the output voltage ripple. Other low ESR capacitors can be
used, according to the needs of the application, without compromising the correct
functioning of the device.
Doc ID 18290 Rev 1
ST2S08B