The S9V11x family of efficient switching regulators (also called switched-mode power supplies (SMPS) or DC-to-DC converters) use a buck-boost topology to convert both higher and lower input voltages to a regulated output voltage. They take input voltages from 2 V to 16 V and increase or decrease them as necessary, offering a typical efficiency of over 85% and a typical output current of up to 1.5 A. The flexibility in input voltage offered by this family of regulators is especially well-suited for battery-powered applications in which the battery voltage begins above the regulated voltage and drops below as the battery discharges. Without the typical restriction on the battery voltage staying above the required voltage throughout its life, new battery packs and form factors can be considered.
The different members of this family offer different output voltage options, from fixed voltages with selectable alternatives to adjustable voltages that can be set anywhere between 2.5 V and 9 V using a precision 12-turn potentiometer. Some versions also have an adjustable low-voltage cutoff that can be set anywhere in the 2 V to 16 V output voltage range and used to prevent your battery from over-discharging. This is particularly useful for battery chemistries that can be damaged when over-discharged, including Li-ion and LiPo.
These regulators have short-circuit protection, and thermal shutdown prevents damage from overheating; they do not have reverse-voltage protection. Note that the startup current is limited to approximately 700 mA until the output voltage reaches the nominal voltage; after startup, the available current is a function of the input voltage (see the Typical efficiency and output current section below).
- Input voltage: 2 V to 16 V (note: this regulator requires 3 V to start, but it can operate down to 2 V after startup)
- Fixed 3.3 V output with +5/-3% accuracy (can be changed to 5 V using the SEL pin)
- Typical maximum continuous output current: 1.5 A (when input voltage is close to the output; the Typical efficiency and output current section below shows how the achievable continuous output current depends on the input and output voltages)
- Power-good indicator can be used to tell when the regulator has reached and is maintaining its target output voltage
- Power-saving feature maintains high efficiency at low currents (quiescent current is less than 1 mA while enabled and approximately 7 µA per volt on VIN when regulator is disabled)
- Integrated over-temperature and short-circuit protection
- Small size: 0.5" × 0.6" × 0.17" (12.7 × 15.3 × 4.3 mm)
During normal operation, this product can get hot enough to burn you. Take care when handling this product or other components connected to it.
The step-up/step-down regulator has five main connections all located along the same edge of the board: the output voltage (OUT), ground (GND), the input voltage (IN), an enable input (EN), and a power good indicator (PG). A sixth pin, SEL, can optionally be used to change the output voltage from 3.3 V to 5 V.
The output voltage, VOUT, defaults to 3.3 V but can be changed to 5 V with output voltage selection pin whose operation is described below.
The input voltage, VIN, should be between 3 V and 16 V when the regulator is first powered. After it is running, it can continue operating down to 2 V. Lower inputs can shut down the voltage regulator; , so you should ensure that noise on your input is not excessive, and you should be wary of destructive LC spikes (see below for more information).
The regulator, which is enabled by default, can be put into a low-power sleep state by reducing the voltage on the EN below 0.7 V, and it can be brought out of this state again by increasing the voltage on EN past 0.8 V. The quiescent current draw in this sleep mode is dominated by the current in the 100 kO pull-up resistor from ENABLE to VIN, which is approximately 7 µA per volt on VIN (e.g. approximately 20 µA with 3 V in). The tight tolerance of the enable input allows a precise low-VIN cutoff to be set, such as with the output of an external voltage divider powered by VIN, which is useful for battery powered applications where draining the battery below a particular voltage threshold could permanently damage it.
The ?power good? indicator, PG, is an open-drain output that goes low when the regulator?s output falls below around 90% of the nominal voltage, including when the enable pin is held low. The power good indicator is held low until the output reaches 95% of the nominal voltage when it is powering up or coming out of low-power mode. Otherwise, the PG pin is high-impedance, so an external pull-up resistor is required to use this pin.
The select input, SEL, can be driven above 1.1 V (up to 16 V) to change the output voltage of the regulator to 5 V. Driving the pin low or leaving it disconnected sets the output to 3.3 V. To permanently set the output to 5 V, you can solder a piece of wire between SEL and the unpopulated pad next to it, which is pulled up to VIN; the following picture shows an example of this:
|Size:||0.5" × 0.6" × 0.17"|
|Minimum operating voltage:||2 V|
|Maximum operating voltage:||16 V|
|Maximum output current:||1.5 A|
|Output voltage:||3.3 V|
|Reverse voltage protection?:||N|
|Maximum quiescent current:||1 mA|