ZHCSCC8E March 2014 – July 2018 TPS92601-Q1 , TPS92602-Q1
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
Each boost controller uses an adjustable fixed-frequency peak-current-mode control. In a constant-current application, the device senses the output current across an external shunt resistor at the ISPx and ISNx pins, amplifies and level-shifts it to ground-reference, and compares it to the voltage applied on the ICTRLx pin by the primary error amplifier, which drives the COMPx pin. In a constant-voltage application, the device compares the output voltage through external resistors on the OVFBx pin to an internal 2.2-V voltage reference by a secondary error amplifier, which drives the COMPx pin. Depending on the chosen application, only one of the error amplifiers is active.
An internal oscillator initiates the turnon of the external boost-power NMOS switch. The device compares the error-amplifier output to the switch current sensed on the ISNSx pin. When the power-switch current reaches the level set by the COMPx voltage, the power NMOS switch turns off. The COMPx pin voltage increases and decreases as the output current increases and decreases. The device implements a current limit by clamping the COMPx pin voltage to a maximum level.