TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
4/8
Version: B13
Application Information
Setting the Output Voltage
Application circuit item shows the basic application circuit with AX5511 adjustable output version. The external
resistor sets the output voltage according to the following equation:
)
R1
R2
+(1 ×1.238V = V
OUT
For most applications, R2 is a suggested a value by 390K~820KΩ. Place the resistor-divider as close to the IC as
possible to reduce the noise sensitivity.
Under Voltage Lockout (UVLO)
To avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the
device, if the input voltage falls below (2.35V-130mV).
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input
capacitor impedance at the switching frequency shall be less than input source impedance to prevent high
frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must
be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and
small temperature coefficients. A 10µF ceramic capacitor for most applications is sufficient. For a lower output
power requirement application, this value can be decreased.
Output Capacitor Selection
The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The
output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R
dielectrics are recommended due to their low ESR and high ripple current. A 4.7uF ceramic capacitors works for
most of the applications. Higher capacitor values can be used to improve the load transient response.
Layout Guide
