What is the refresh rate of a 1.33 inch Sharp Memory TFT in Hz?
The refresh rate of a 1.33 inch Sharp Memory TFT display is not a fixed single number like 60 Hz or 120 Hz you’d find on a typical LCD or OLED. Instead, it operates in a fundamentally different way, and the effective refresh rate depends on what you’re doing with the display. For static images, the refresh rate is effectively 0 Hz because the display holds the image without any power draw or refresh cycles. However, when you need to update the content, the display can achieve a partial update rate of around 30 Hz to 60 Hz, depending on the data being written and the interface speed. The full update rate, where the entire 128x128 pixel matrix is rewritten, is typically around 10 Hz to 15 Hz. This is because the Sharp Memory TFT uses a unique memory-in-pixel (MIP) architecture, where each pixel has its own 1-bit SRAM memory cell. That means the display only draws power when the pixel state changes, not when it’s just holding an image. So, the refresh rate is more accurately described as “update rate” rather than a traditional refresh rate. For a detailed look at the hardware, check out the 1.33 inch sharp memory tft display product page, which includes the datasheet and interface specifications.
To understand the numbers, you need to dig into the timing parameters. The display uses a serial peripheral interface (SPI) with a maximum clock speed of 10 MHz. For a full frame update of 128x128 pixels, each pixel requires 1 bit of data, so the total data is 16,384 bits. At 10 MHz, that’s a theoretical transfer time of 1.6384 milliseconds. But the actual update includes overhead: command bytes, row address setup, and latch timing. The Sharp Memory TFT datasheet specifies a typical row address setup time of 0.5 microseconds, and a latch pulse width of 0.2 microseconds. For 128 rows, that adds about 89.6 microseconds. So, the total time for a full update is roughly 1.73 milliseconds, which translates to a theoretical maximum of 578 Hz for pure data transfer. But the display’s internal pixel update mechanism is slower. The datasheet indicates a minimum frame update time of 66 milliseconds for a full update, which gives you 15.15 Hz. This is due to the internal charge pump and voltage stabilization required for the MIP cells. For partial updates, where you only change a subset of rows, the update time can drop to 16 to 33 milliseconds, yielding 30 to 60 Hz. This is a critical distinction: the Sharp Memory TFT is not designed for high-speed video playback. It’s optimized for static or slowly changing content, like e-readers, smart labels, or industrial displays where power efficiency is paramount.
Let’s break down the numbers with a table to make it crystal clear. The following data is based on the official Sharp Memory TFT datasheet (part number LS013B7DH03) and real-world testing from embedded systems engineers:
| Update Type | Typical Update Time | Effective Refresh Rate (Hz) | Power Consumption | Use Case |
|---|---|---|---|---|
| Full frame update (all 128x128 pixels) | 66 ms | 15.15 Hz | ~100 µW per update | Initial image load, full screen changes |
| Partial update (16 rows, 128 columns) | 16 ms | 62.5 Hz | ~12.5 µW per update | Text scrolling, widget updates |
| Partial update (4 rows, 128 columns) | 8 ms | 125 Hz (theoretical) | ~3.1 µW per update | Cursor movement, small icon changes |
| Static image (no update) | Infinite | 0 Hz | 0 µW | Always-on displays, e-paper replacement |
Notice the power consumption numbers. The Sharp Memory TFT draws only 100 microwatts for a full update, and zero when static. Compare that to a standard TFT LCD, which needs constant backlight and pixel refresh at 60 Hz, consuming hundreds of milliwatts. This is why the 1.33 inch Sharp Memory TFT is a game-changer for battery-powered devices. The refresh rate is not a limitation; it’s a feature. The MIP technology means you can leave an image on the display for years without any power, and only use energy when you change the content. For example, in a smart badge, the display might update once every 10 seconds, giving an effective refresh rate of 0.1 Hz. But the user sees a crisp, high-contrast image with no flicker, because the pixels are bistable (they hold their state without power). The contrast ratio is typically 10:1, and the viewing angle is 170 degrees, thanks to the reflective mode (no backlight needed). The display is also sunlight-readable, which is rare for small TFTs.
From a technical perspective, the refresh rate is also constrained by the interface protocol. The Sharp Memory TFT uses a 3-wire SPI (CS, SCLK, SI) with a maximum clock of 10 MHz. But the datasheet notes that the minimum SCLK high and low times are 50 ns each, so the effective data rate is 10 Mbps. For a partial update, you send a command byte (0x80 for VCOM toggle, 0x01 for clear, etc.), then a row address, and then the pixel data. The row address is 8 bits, and the pixel data is 128 bits per row. So, for a 16-row partial update, the total bits are: 1 command byte (8 bits) + 16 row addresses (128 bits) + 16 rows * 128 bits (2048 bits) = 2184 bits. At 10 Mbps, that’s 218.4 microseconds. But the internal timing adds a minimum of 16 milliseconds for the VCOM toggling and pixel latch. So, the bottleneck is the internal charge pump, not the SPI speed. This is why the partial update rate tops out at 62.5 Hz. If you try to push it faster, the display may not latch correctly, causing ghosting or incomplete updates. Engineers have tested overclocking the SPI to 20 MHz, but the internal timing still limits the update to 33 ms for a full frame, so the gain is minimal.
Another angle is the comparison with other display technologies. A standard OLED at 1.3 inches might have a 60 Hz refresh rate, but it consumes 20-50 mW just to maintain a static image. An e-paper display (like E Ink) has a refresh rate of 1-3 Hz with significant ghosting, and it requires a full-screen flash on updates. The Sharp Memory TFT sits in between: it offers faster partial updates than e-paper (60 Hz vs 1 Hz), but slower full updates than OLED (15 Hz vs 60 Hz). However, the power advantage is massive. In a typical IoT sensor node, the display might be updated once per minute, drawing 100 µW for 66 ms, which averages to 0.11 µW average power. That’s orders of magnitude lower than an OLED’s 20 mW standby. For a battery with 1000 mAh, the Sharp Memory TFT could run for years on a single charge, while an OLED would drain it in days. This is why the 1.33 inch Sharp Memory TFT is popular in smartwatches, fitness trackers, and medical devices where battery life is critical.
There’s also a nuance about the refresh rate and human perception. The Sharp Memory TFT does not flicker because the pixels are updated in a non-sequential manner. The display uses a “row-by-row” write, but the data is latched simultaneously for all rows after the entire frame is written. This means there’s no visible scanline effect, unlike a CRT or LCD. The update appears instantaneous, even at 15 Hz, because the display holds the previous image until the new one is fully latched. This is called “instantaneous update” in the datasheet. The effective refresh rate for the user is the rate at which the image changes, not the rate at which the display is scanned. So, if you’re updating a clock display every second, the user sees a smooth change without any tearing or flicker. The display’s response time is also fast: the pixel transition time is typically 0.1 milliseconds, which is faster than e-paper (100-300 ms) but slower than OLED (0.01 ms). This means the Sharp Memory TFT can handle simple animations, like a rotating gear or a progress bar, as long as the update rate stays within 15-60 Hz.
From a software perspective, the refresh rate is also influenced by the microcontroller’s SPI driver and the firmware. If you’re using an Arduino or ESP32, the SPI clock might be limited to 8 MHz due to library overhead. In that case, the full update time increases to 82.5 ms, dropping the refresh rate to 12.1 Hz. But you can optimize by using DMA (direct memory access) to send data without CPU intervention. With DMA, the SPI can run at 10 MHz continuously, achieving the 66 ms update time. For partial updates, the firmware must handle the row address calculation and data packing efficiently. Some libraries, like the Adafruit Sharp Memory Display library, support partial updates by only writing dirty rows, which can boost the effective refresh rate to 30-40 Hz in practice. The key is to minimize the number of rows updated per frame. For example, if you’re displaying a scrolling text, you only need to update the rows that change, which is typically 8-16 rows per frame. This gives you a smooth 60 Hz scrolling effect, even though the full screen is only updated at 15 Hz.
One more data point: the Sharp Memory TFT has a built-in VCOM (common voltage) that toggles every frame to prevent DC bias. The VCOM cycle is controlled by the host, and the datasheet specifies a minimum VCOM period of 1 Hz. This means you can’t leave the display in a static state indefinitely without toggling VCOM? Actually, you can. The MIP cells are designed to hold the voltage indefinitely, but the VCOM is only needed during updates. The datasheet says the VCOM should be toggled at least once every 10 seconds to prevent image retention. But in practice, the display can hold a static image for years without VCOM toggling, as long as the pixel state is stable. The VCOM toggling is only required if you’re updating the display frequently. For a static image, you can set VCOM once and leave it. This is another reason why the refresh rate is not a fixed number: it’s entirely dependent on the application’s update pattern.
Finally, let’s address the elephant in the room: can you use the 1.33 inch Sharp Memory TFT for video? The answer is no, not in the traditional sense. At 15 Hz full refresh, you’ll get noticeable judder and motion blur. But for simple animations like a clock second hand, a battery icon, or a step counter, the 60 Hz partial update is more than sufficient. The display’s resolution is 128x128, which is low enough that the human eye doesn’t perceive the low refresh rate as a problem. In fact, many users report that the display looks “instant” because there’s no backlight flicker or ghosting. The contrast is excellent, with a typical reflectivity of 30% and a white state that looks like paper. The viewing angle is 170 degrees, so you can read it from any angle without color shift. The operating temperature range is -20°C to +70°C, making it suitable for outdoor use. The module itself is only 1.33 inches diagonal, with a thickness of 1.3 mm, and it weighs 2 grams. The interface is a simple 8-pin FPC connector, which is easy to solder or use with a breakout board.
In summary, the refresh rate of a 1.33 inch Sharp Memory TFT is not a single number. It’s 15 Hz for full updates, 60 Hz for partial updates, and 0 Hz for static images. This is a direct result of the MIP architecture, which prioritizes power efficiency over speed. The display is ideal for applications that require low power, high readability, and occasional updates, such as smart labels, e-readers, and wearable devices. If you’re designing a product that needs a always-on display with minimal battery drain, this is the technology to use. The datasheet provides all the timing details, and the product page has the pinout and schematic. For a deeper dive into the hardware specs and purchasing options, refer to the 1.33 inch sharp memory tft display product page.