LILYGO Refreshes T-SIM Lineup With Lower-Power ESP32-S3 Boards

The most visible change in LILYGO’s T-SIM / T-A Standard Series isn’t a faster radio or a bigger flash chip. It’s the deep-sleep current, which the company says now sits between roughly 128 µA and 166 µA across several variants. Earlier boards in the same family pulled as much as 1.1 mA in the same state, an almost ten-fold gap that decides how many seasons a battery-powered remote sensor can live in the field before someone has to drive out and swap an 18650.

The refresh, first detailed by LinuxGizmos, lines up six ESP32-S3 cellular development boards under one pinout, one module choice, and one set of optional peripherals. Hobbyists, agritech prototypers, and small fleets running remote monitoring on Cat-M, NB-IoT, or LTE Cat-1 are the buyers; the boards now arrive with a Qwiic connector, optional camera headers, eSIM pads, and seamless USB-to-battery switching as defaults rather than as fork variants.

What Changed in the Standard Series Refresh

The lineup keeps its modem names. The T-SIM7000G-S3, T-SIM7080G-S3, T-SIM7670G-S3, and the T-A7670 family all carry their previous radio identities. What’s different is what sits around the modem.

Every Standard variant is now built on the ESP32-S3-WROOM-1 (N16R2) module, with 16 MB of flash and 2 MB of PSRAM. That replaces a mix of earlier ESP32-WROVER-B and ESP32-S3 N16R8 configurations used across older T-SIM revisions. The PSRAM figure is worth pausing on: it’s smaller than the 8 MB PSRAM the earlier S3 boards shipped with, a deliberate trade against the WROOM-1’s lower idle current and tighter PCB footprint. For Arduino-style sketches and AT-command modem control, 2 MB of PSRAM is comfortable. For heavier edge-AI inference with framebuffers and TensorFlow Lite Micro models, builders may need to think about what fits.

The Standard boards add Qwiic connectivity, GNSS routing to the SoC on variants that didn’t have it before, PPS (pulse per second, the one-edge-per-second timing pulse a GNSS receiver provides for clock discipline) support on selected models, eSIM solder pads, and pin compatibility across the family. A second USB Type-C port is now standard for modem firmware updates alongside the ESP programming port, which removes one of the more annoying parts of the older workflow.

The Modem Lineup at a Glance

The Standard Series collapses six product pages into one decision tree. The radio class drives the rest of the spec sheet.

The two Cat-M / NB-IoT boards target the kind of project that needs a packet every few minutes, not a video stream. SIMCom’s own datasheet for the SIM7080G notes that the module supports Power Saving Mode and Extended Discontinuous Reception, two LTE features that let a device idle in a near-off state between scheduled wake-ups. The two LTE Cat-1 boards do the heavier lifting; the SIM7670G is the one builders pick when frames from a camera need to leave the field reliably.

Deep-Sleep Current Drops Nearly Ten-Fold

Average deep-sleep current is the number that decides whether a solar-charged remote sensor survives a cloudy week. The Standard Series moves it sharply.

The figures published in the comparison table:

• Approximately 128 µA on the lowest Standard variants, climbing to roughly 166 µA across the rest.
• Up to 1.1 mA reported for earlier T-SIM boards in the same deep-sleep state.
• That’s a reduction of roughly 8.6 times at the floor, large enough to swing the duty cycle math for a battery-powered node from days to weeks of standby on a single 18650 cell.

Two design choices drive the drop. The first is the move to the WROOM-1 (N16R2) module, which idles cleaner than the older WROVER-B and N16R8 parts the family used to ship. The second is the seamless power switching circuit, which removes a leakage path between USB and battery rails that some earlier T-SIM revisions carried. The catch sits in the PSRAM column: 2 MB is plenty for AT-command modem buffers, MQTT message queues, and a small image frame, but it isn’t generous if a builder wants to layer a real edge-AI vision pipeline on top.

Qwiic, Camera, and the Cellular-Camera BOM

The second-order story sits here. Building a remote camera node that uploads frames over LTE used to mean stitching three boards together: an ESP32-S3 dev board for the brains, a separate cellular modem with its own UART link and power management, and an OV-series camera carrier on yet another connector. The wiring was the project. The Standard Series turns that into one PCB.

Across the lineup, LILYGO now routes:

• An OV-series camera interface with GPIO mappings, allowing OV2640 or OV5640 modules to drop in directly for face detection, license-plate capture, or wildlife monitoring.
• A Qwiic connector (Sparkfun’s 4-pin I2C/UART standard, which lets sensors plug in without soldering) for downstream peripherals such as environmental sensors and OLED screens.
• An 18650 lithium-cell holder with USB-C and solar charging inputs, plus the new seamless power switching that hands off between sources without a brownout.
• A microSD slot for local frame buffering when the cellular link is offline, plus eSIM solder pads for fleet deployments that don’t want a physical SIM tray.

Before this refresh, a maker building a solar-powered remote camera-plus-cellular sensor would have priced two boards plus interconnect at around the cost of one mid-range smartphone. The Standard Series puts that bill of materials on a single PCB under one firmware image, which is the change that actually matters for small-fleet deployments. Whether the bet pays off depends on builders accepting the 2 MB PSRAM ceiling. For asset trackers, environmental loggers, and occasional-frame surveillance, the trade is straightforward.

Regional Bands and Modem Selection

The modem decision is regional first, application second. LILYGO splits the LTE Cat-1 family into two SKUs because the LTE band landscape doesn’t accept one global radio.

The A7670E variant is documented for Europe, the Middle East, Africa, South Korea, and Thailand. The A7670G is the global model, which is also the one most North American buyers pick when they want Cat-1 reach without committing to a region-specific board. The SIM7670G is the broadly compatible LTE Cat-1 option that ships with integrated GNSS routing to the ESP32-S3 in the Standard revision, a feature that the earlier non-Standard T-SIM7670G S3 did not include. LILYGO’s product page for the T-SIM7670G S3 spells out the difference between the two SKUs directly:

Feature T-SIM7670G S3 (H707) vs T-SIM7670G S3 Standard (H802): module changes from ESP32-S3-WROOM-1 (N16R8) to ESP32-S3-WROOM-1 (N16R2); QWIIC, seamless power switching, GNSS routing to SoC, GNSS PPS, eSIM pad, and camera interface all change from absent to present on the Standard SKU.

For builders deciding between Cat-M / NB-IoT and Cat-1, the trade is throughput against power. NB-IoT downlink on the SIM7080G tops out around 136 Kbps; Cat-1 on the SIM7670G clears single-digit megabits comfortably. A weather station does not need Cat-1. A field camera that uploads JPEG frames every fifteen minutes probably does.

Caveats Worth Knowing Before You Order

The refresh is genuinely useful, but the Standard Series carries a few rough edges worth flagging before a build order goes out.

• The PSRAM cut from 8 MB to 2 MB is real. Edge-AI vision projects that worked on the earlier S3 N16R8 boards may need to shrink their models or move framebuffers to PSRAM-light strategies.
• The Qwiic connector on some T-SIM boards has historically been wired as UART rather than I2C, a point earlier buyers flagged in product reviews. Builders should check the silkscreen and the per-board documentation in the LilyGo-Modem-Series GitHub repository before assuming an I2C-only sensor will work.
• LILYGO’s note that availability varies by modem selection is the practical headline. The A7670E ships into Europe-friendly stock channels; the A7670G global model is the safer pick for buyers outside listed regions.
• Cat-M and NB-IoT coverage is carrier-dependent. The SIM7080G supports the bands, but a builder in a market without commercial NB-IoT roaming will spend an evening on AT+CPSI debugging before the first packet leaves the bench.

Frequently Asked Questions

How Is the Standard Series Different From the Original T-SIM Boards?

The Standard Series replaces the older ESP32-S3-WROOM-1 (N16R8) and ESP32-WROVER-B modules with the WROOM-1 (N16R2), and it adds Qwiic, camera interfaces, seamless power switching, GNSS routing to the SoC, GNSS PPS, and eSIM pads as defaults across the lineup. Deep-sleep current also drops to roughly 128 to 166 µA on Standard variants, compared with up to 1.1 mA on earlier boards.

Which Standard Board Should I Pick for Battery-First Deployments?

The T-SIM7080G-S3 is the strongest pick when battery life matters more than throughput. Its SIM7080G modem supports Power Saving Mode and Extended Discontinuous Reception, two LTE features designed for low-data IoT nodes that wake briefly and sleep deeply.

Can I Use the Camera Interface for Edge-AI Vision?

Yes, the boards expose GPIO mappings for OV-series image sensors such as the OV2640 and OV5640. The constraint is the 2 MB PSRAM ceiling on the WROOM-1 (N16R2) module, which limits framebuffer size and the depth of TensorFlow Lite Micro models a builder can run alongside the cellular stack.

Which Modem Covers North America Best?

For LTE Cat-1, the A7670G global SKU is the broadly compatible choice for North American deployments. For Cat-M and NB-IoT, the SIM7080G covers most North American Cat-M bands, but carrier roaming for NB-IoT is still patchy outside specific commercial agreements.

Is There a Seamless Way to Switch Between USB and Battery Power?

Yes, the Standard Series introduces seamless power switching as a default circuit, which hands off between USB Type-C input and the 18650 cell without a brownout. Earlier T-SIM boards relied on the on/off switch being bypassed when external batteries were attached to the VBAT pin, which made unattended deployments fragile.

Where Can I Find Reference Code and Schematics?

LILYGO maintains the LilyGo-Modem-Series repository on GitHub with quick-start guides for the T-A7670X-S3-Standard, T-SIM7670G-S3-Standard, T-SIM7000G-S3-Standard, T-SIM7080G-S3-Standard, and T-SIM7600G-S3-Standard variants. The repo also documents the AT-command path through the modem and the TinyGSM fork required for A7670 and SIM767x parts.

The T-SIM / T-A Standard Series is listed on LILYGO’s website now, with availability varying by modem selection. The boards a remote-sensor builder reaches for this season are the same six names as before, on a refreshed PCB that finally treats Qwiic, camera, GNSS routing, and seamless power as table stakes rather than as upgrades.