ST1S12XX12 STMicroelectronics, ST1S12XX12 Datasheet - Page 10

• Manufacturer Part Number: ST1S12XX12
• Description: Synchronous rectification with inhibit, 0.7 A, 1.7 MHz fixed, step-down switching regulator
• Manufacturer: STMicroelectronics

Specifications of ST1S12XX12

• Typical Efficiency: > 90%
• Not Switching Quiescent Current: max 650 μA over temperature range

Application notes
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10/20
Application notes
The ST1S12 is an adjustable current mode PWM step-down DC-DC converter with internal
0.7 A power switch, packaged in TSOT23-5L. This device is a complete 0.7 A switching
regulator, with its internal compensation eliminating the need for additional components.
Because the ST1S12 an adjustable regulator, the output voltage is determined by an
external resistor divider. The desired value is derived by the following equation:
Equation 1
V
For the device to function only a few component are required: an inductor, two capacitors
and the resistor divider. The inductor selected must be capable of non saturation at peak
current level. Moreover, its value can be selected taking into account that a large inductor
value increases efficiency at low output current and reduces output voltage ripple, while a
smaller inductor can be used when it is important to reduce package size and the total cost
of the application. Finally, the ST1S12 has been designed to work properly with X5R or X7R
SMD ceramic capacitors both at the input and at the 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 need of the application without compromising the
correct functioning of the device.
O
= V
FB
[1 + R
1
/ R
2
]
Doc ID 14314 Rev 5
ST1S12XX, ST1S12XX12, ST1S12XX18