DS3231 / DS1307 RTC Shortage? Replacing with Micro Crystal RV Series (Heads-up: Firmware Must Change)
Facing cost and lead-time pressure on the DS3231 / DS1307, the Micro Crystal RV series is a functional alternative — but not a drop-in: the DS parts use I²C address 0x68, while RV-8803/RV-3028/RV-8564 use 0x32/0x52/0x51 with different register maps, so a swap requires firmware changes. This guide sorts the choice by whether you need temperature compensation and makes the migration cost clear.
Up front: the RV series is a functional alternative, not a drop-in
Let’s be clear up front: Micro Crystal’s RV series is a functional alternative to the DS3231 / DS1307, not a pin-to-pin or software drop-in. The DS3231 and DS1307 both use I²C address 0x68; the matching RV parts each use a different address (RV-8803-C7 = 0x32, RV-3028-C7 = 0x52, RV-8564 = 0x51) and their register maps are entirely different. So after a swap the firmware must change in at least two places: the I²C device address, and the whole register mapping (time/date/control/interrupt registers all sit at different locations); the pinout and package also differ, so the PCB must be re-laid-out. Factor “changing the address means changing code” into the migration cost first, and the selection below becomes easy.
DS3231 vs DS1307: compensated vs basic
First tell the originals apart: the DS3231 is a high-accuracy RTC with an integrated TCXO (temperature-compensated oscillator) plus crystal, guaranteed ±3.5 ppm over −40~+85°C and ±2 ppm at room temperature; the DS1307 is a basic RTC needing an external 32.768kHz crystal with no temperature compensation, its accuracy entirely dependent on the external crystal and layout. Both use I²C address 0x68. So “do you need temperature compensation” is the first fork in choosing a replacement: if you chose the DS3231 for its compensated accuracy, the replacement must also be compensated to not lose accuracy; if you only used the DS1307 for basic timekeeping, the replacement need not pay for compensation.
The mapping: DS3231 → RV-8803; DS1307/PCF8563 → RV-8564 / RV-3028
Coming from a DS3231 (high accuracy that needs temperature compensation) → choose RV-8803-C7: like the DS3231 it has integrated temperature compensation (this one is a digital DTCXO), guaranteed ±3 ppm over −40~+85°C (a touch better than the DS3231’s ±3.5) and ±1.5 ppm at room temperature — equal or better accuracy. Coming from a DS1307 or PCF8563 class (basic timekeeping, no compensation needed) → choose RV-8564 or RV-3028-C7: if you want the least porting effort and were already on PCF8563, choose RV-8564 (register-compatible with PCF8563); if you want extreme low power (coin-cell long standby, wearable/IoT), choose RV-3028-C7 (~45nA timekeeping current). One important caution: do not use the RV-3028 to cover a DS3231 that needs compensation — the RV-3028’s ±1 ppm holds only at 25°C and drifts along a parabola away from room temperature; it is not a compensated part.
⚠️ Two traps: I²C address + registers; 7-bit vs 8-bit
1) I²C address + register map: DS3231/DS1307 are 0x68, the RV parts are 0x32/0x52/0x51, and the register layouts differ — the firmware’s address and register accesses must be rewritten per the new datasheet. The one exception is RV-8564 ↔ PCF8563, which are register-compatible (same 0x51, same register map, the same Linux driver works), so if you were on PCF8563 (not the DS series), moving to RV-8564 is nearly a software drop-in. 2) 7-bit vs 8-bit address notation: for the same chip, the 7-bit address (e.g. RV-8803’s 0x32) and the “8-bit write byte” (0x64) differ by one bit shift — do not treat them as two different parts; when porting, first confirm which form your driver or library expects.
What you gain (power / size / automotive grade)
Moving to the RV series buys three real advantages: 1) Power — the RV-3028’s ~45nA timekeeping current and the RV-8803’s ~240nA are far below the DS3231’s µA~mA class, ideal for battery/coin-cell long-life designs; 2) Size — the RV-8803/RV-3028 are just 3.2×1.5×0.8mm, much smaller than the DS3231’s 16-SO; 3) Automotive grade — all three have an AEC-Q200 option, which the standard DS3231/DS1307 parts do not. Add the cost and lead-time pressure commonly seen on the DS3231 in recent years, and it is a common migration motivation. JLink Technology is an authorized Micro Crystal distributor supplying RV-8803-C7 / RV-3028-C7 / RV-8564 and other RTCs; tell us your current DS3231/DS1307 design and accuracy/power needs and we will map the matching replacement, provide samples and datasheets, and reply with stock, pricing and lead time.
Products mentioned
RV-8803-C7 High-Accuracy I²C RTC Module
The RV-8803-C7 is a high-accuracy I²C real-time-clock module from Micro Crystal with a built-in 32.768kHz DTCXO, ±3ppm accuracy (−40~85°C), ~240nA timekeeping at 3V, a wide 1.5~5.5V supply, plus alarm, timer, interrupt output, and a time-stamp event input.
RV-3028-C7 Extreme Low Power I²C RTC Module
The RV-3028-C7 is one of the industry's most power-efficient RTC modules, drawing typically just ~45 nA. It integrates a tuned crystal, offers an I²C interface, and includes alarm, timer, and event logging — ideal for coin-cell powered wearables, meters, and IoT applications needing long battery life.
RV-8564 I²C RTC Module (PCF8563-Compatible)
The RV-8564 is an I²C RTC/calendar module from Micro Crystal with an embedded 32.768kHz crystal, register-compatible with the NXP PCF8563 so existing firmware can be reused. I²C Fast-mode 400kHz, ~250nA timekeeping, a wide 1.2~5.5V supply, plus alarm, timer, programmable CLKOUT, interrupt, and voltage-low detection. SON ceramic package.
Need these components or design help?
JLink Technology provides parts, datasheets, and engineering support.
Request a Quote