introduction

When developing portable battery instruments or industrial process control systems, multi-channel programmable voltage outputs are an essential requirement. If each channel were equipped with its own DAC, reference voltage, and control lines, it would not only lead to a significant increase in PCB area and BOM costs, but also make it difficult to guarantee consistency and synchronization across multiple output channels. The Corebai Micro CBM53D24 single-chip solution integrates four 12-bit buffered DACs, shares a common reference voltage, and employs a single set of 3-wire SPI control lines—effectively addressing the challenges of multi-channel analog design.

I. Multi-channel DAC designs commonly encounter these three major challenges

When developing a multi-channel analog board, the multi-channel independent DAC solution presents three unavoidable engineering challenges:

• PCB footprint and BOM costs have doubled

For each additional analog output channel, an extra DAC, a reference source, and corresponding decoupling capacitors are required, leading to a simultaneous increase in component quantity and PCB footprint.

• Cabling complexity has surged, and the risk of crosstalk has increased.

Various DACs require independent clock, data, and reference traces; digital noise can easily crosstalk into analog outputs, significantly increasing the complexity of PCB layering design.

• Multi-channel consistency cannot be guaranteed.

In a parallel DAC configuration employing independent reference sources, each channel exhibits inherent variations in temperature drift and initial accuracy, making it difficult to achieve uniform error characteristics when multiple channels are simultaneously adjusted via voltage control.

Is it possible to integrate "multi-channel + buffering + serial control" into a single chip, enabling four analog outputs to share a single reference and be configured via a single interface? The Corebai Micro CBM53D24 offers precisely this solution: a single-chip integrated 4-channel, 12-bit, buffered-voltage-output DAC featuring 3-wire serial control, rail-to-rail output, single-supply operation from 2.5V to 5.5V, and industrial temperature range from −40 °C to +105 °C. It is ideally suited for applications requiring "multi-channel output, low power consumption, and synchronous switching," such as portable battery-powered instruments, industrial multi-channel programmable voltage sources, and programmable gain/attenuation devices.

II. Positioning: CBM53D24 General-Purpose Buffer Quad DAC

Key specifications: CMOS process, 4-channel architecture, 12-bit resolution, resistor-string architecture with buffered voltage output DAC; each channel features a built-in output buffer amplifier and rail-to-rail output; operating voltage range: 2.5V–5.5V; industrial temperature range: −40 °C to +105 °C; supports 3-wire serial interfaces including SPI, QSPI, MICROWIRE, and DSP, with a maximum clock speed of 30 MHz.

III. Three Core Differentiation Advantages: Addressing the Pain Points of Multi-Path Design

3.1 Dual-buffer register with four-channel zero-delay synchronous refresh

The primary challenge of multi-channel systems is that the outputs of different channels "do not switch states at the same instant." The CBM53D24 is designed with four DACs sharing a single REFIN reference pin, and all DAC outputs can be refreshed simultaneously via a single LDAC control bit.

• Dual-buffer registers: Each DAC features two built-in registers—an input register (temporary buffer) and a DAC register (direct output control).

• LDAC synchronization bit: The synchronization control bit in the 16-bit control word, serving as the core switch for multiplexed synchronization.

3.2 SYNC: Frame synchronization for extending a single serial port to multiple DACs

SYNC is the low-active-frame synchronization pin; multiple CBM53D24 chips can share the same set of SCLK and DIN signal lines, with each chip being selected sequentially via SYNC (a typical extension is to use a 74HC139 to perform 2-to-4 decoding). A single MCU can therefore drive multiple quad DACs, allowing the number of channels to be increased.

3.3 Implement the automatic sleep interface to continuously reduce the overall static power consumption of the system.

After each complete 16-bit SPI write operation, the SCLK and DIN digital input buffers automatically enter a low-power sleep mode, reactivating only when triggered by a falling edge of SYNC. This design continuously reduces the static current on the digital interface side, making it well-suited for battery-powered low-power devices.

IV. Critical Considerations for Model Selection: Performance Boundaries and Design

1. Linear precision is categorized into versions A and B

12-bit resolution indicates only the resolution steps and does not imply high precision; typical INL is ±2LSB (at 25 °C), with full-temperature limits of ±16LSB for Version A and ±10LSB for Version B; DNL is maximum ±1LSB, and the output exhibits monotonic behavior without code loss; offset and gain errors remain within fixed ranges, and a margin should be reserved for precision proportional circuits.

2. The baseline has no built-in buffer

REFIN has an input impedance of 45 kΩ and lacks an internal buffer amplifier; for high-precision applications, an external operational amplifier must be used to buffer the reference voltage in order to reduce load noise.

3. Compatible only with static voltage regulation

Swing rate: 0.7 V/µs; rise time: 9 μs; bandwidth: 200 kHz; not suitable for high-frequency waveform generation applications.

4. The output has a 20 mV low-level dead zone.

This is only observed under negative offset conditions; therefore, a margin should be reserved for the small-signal output circuit near 0 V.

5. Excellent channel and power supply rejection capabilities

The PSRR is-60 dB, ensuring minimal impact from power supply fluctuations; the channel DC crosstalk is extremely low, and interference from multi-channel synchronous outputs is negligible.

6. Output drive parameters

Output impedance: 0.5 Ω; 5 V short-circuit current: 25 mA; capable of stably driving a parallel load consisting of 2 kΩ resistance and 500 pF capacitance.

V. Low-power design: battery device standby power consumption reduced to the hundred-nA range

Many engineers focus solely on resolution while overlooking the critical importance of power consumption control for battery-based products.

• Nominal operating current: typical 600 µA with 5 V supply (maximum 900 µA), and typical 500 µA with 3 V supply (maximum 700 µA).

• Sleep Mode: Set the PD control pin to 0, disable all four DACs, disconnect the output amplifier, and set VOUT to a high-impedance tri-state; internal register data remains intact without loss. Sleep current: 80 nA at 3 V supply, 200 nA at 5 V supply, with a maximum current not exceeding 1 µA; the device exhibits negligible power consumption during extended standby operation, making this the primary power-saving mechanism for portable instruments.

• Wake-up time: from exiting sleep mode to the establishment of the output voltage, typically 5 µs @ 5 V / 2.5 µs @ 3 V, measured from the 16th clock falling edge of the interface. The wake-up delay can be neglected in most slow-speed operating scenarios.

VI. Packaging & Quick Model Selection Guide

The CBM53D24 is available in two 10-pin package variants, both in tape-and-reel packaging:

The temperature range for all applications is industrial-grade: −40 °C to +105 °C.

VII. Typical Real-World Application Scenarios

1. Portable battery testing instrument

By leveraging nA-level sleep power consumption to reduce overall system standby power loss, four DACs are employed for sensor gain and zero-point offset voltage calibration.

2. Optical communication modules

The bias voltages of the four laser channels are synchronously adjusted; low channel crosstalk ensures consistent output across the multiple optical paths;

3. Industrial PLCs and automated process control

The wide temperature range capability ensures suitability for high-and low-temperature workshop environments, featuring multi-channel synchronous programmable voltage sources and programmable attenuators.