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: 3 V to 16 V
- 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)
- Fixed 3 V low-voltage cutoff with hysteresis protects batteries from over-discharging (quiescent current is approximately 10 �A per volt on VIN when regulator is disabled)
- 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)
- 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. Lower inputs will shut down the voltage regulator; higher inputs can destroy the 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 is put in a low-power sleep state when voltage on the EN pin falls below 0.7 V, and the regulator is brought out of its low-power state when the voltage on EN rises back above 0.8 V. On this regulator version, the EN pin is tied to VIN through a voltage divider that sets the low-voltage cutoff threshold to 3 V (specifically, there is a 154 kO resistor to VIN and a 47 kO resistor to ground). Once the input falls below this 3 V threshold, the regulator will stay disabled until the input rises above 3.4 V (which causes the voltage on EN to rise past its hysteresis threshold of 0.8 V). This low-VIN cutoff is useful for battery powered applications where over-discharging the battery could permanently damage it. The quiescent current draw in this sleep mode is dominated by the current in the voltage divider, which is approximately 10 �A per volt on VIN (e.g. approximately 30 �A with 3 V in).
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:||3 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|
|Low-voltage cutoff:||3V (fixed)|