1. Overview

There are two ways to drive SPI E-paper display: one is that the IC supports internal boost, and the other requires an external boost. Most of the E-paper ICs on the market require an external boost.

2. Principle

IC internal boost: There is a Boost boost circuit inside the IC, and there is no need for boost inductance or N-MOS in the peripheral circuit. However, some necessary capacitors still need to be soldered.

IC external boost: There is no Boost boost circuit inside the IC, and the peripheral circuit requires a boost inductor, N-MOS, and necessary boost capacitor. The GDR signal is generated inside the IC to control the switch of N-MOS to complete the charging and discharging of the inductor and capacitor. The RESE resistor current is sampled to the IC, forming a closed-loop feedback signal to ensure stable voltage output of the boost circuit. The boost circuit provides two types of high voltage to the IC, PREVGH and PREVGL, and the IC uses internal voltage reduction form VSH VSL high-voltage supplies power to E Ink film.

3. Boost converter circuit
  1) IC internal boost

      2) IC external boost

4. Possible reasons why the peripheral boost circuit cannot boost
1) There is a problem with software migration, SPI communication is abnormal;
2) Inductive open circuit;
3) N-MOS parameters wrong;
4) RESE feedback resistor unsoldered;
5) The isolation diode is soldered in reverse.