Analog Devices Inc./Maxim Integrated MAX680CSA

Overview

MAX680CSA from Maxim Integrated is a monolithic CMOS dual charge-pump voltage converter that generates ±10V outputs from a single +5V input supply. It requires four external capacitors, delivers up to 10mA output current per rail, exhibits 150Ω typical positive output source resistance and 90Ω negative output source resistance at +25°C, and operates with an internal 8kHz oscillator - commonly used in op-amp power supplies and data-acquisition systems requiring bipolar rails from logic-level sources.

For engineers reviewing the MAX680CSA datasheet, MAX680CSA pinout, MAX680CSA application, or MAX680CSA equivalent, this device is selected for compact ±10V generation where board space permits discrete capacitor placement, thermal performance across 0°C to +70°C must be verified, and load-dependent output droop modeling is required for precision analog biasing.

Technical Context

The MAX680CSA implements two independent switched-capacitor charge pumps: a positive doubler (V+ = 2×VCC) and a negative inverter (V− derived from V+) operating on complementary 8kHz clock phases. Its internal CMOS switch array uses P-channel and N-channel MOSFETs with no external timing components needed.

Output regulation is unregulated - voltage droop scales linearly with load via defined source resistances (RS+ ≈ 150Ω, RS− ≈ 90Ω at TA = +25°C, VCC = 5V), and ripple is governed by reservoir capacitance and pump frequency (VRIPPLE = ½·IOUT·(1/fPUMP)·(1/CR)).

Key Specifications

Pinout & Package

MAX680CSA is housed in an 8-pin narrow SO package (SOIC-N), 3.9mm × 4.9mm body, 1.27mm pitch, RoHS-compliant. Thermal derating is 5.88mW/°C above +70°C (471mW max at TA = +70°C).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual charge-pump voltage converter applications.

Compared with MAX680CSA, MAX681CPD eliminates external capacitors at the cost of fixed internal values and larger package, while MAX864CPA offers higher-frequency operation and smaller caps but demands updated layout and filtering - neither is pin-compatible, and all require distinct capacitor networks and thermal validation.

Availability

MAX680CSA is available at Aetrix Electronics and suitable for operational amplifier power supplies, data-acquisition systems, and panel meters requiring stable component supply with industrial temperature tolerance and long-lifecycle support.

Supply support for MAX680CSA includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.

The MAX680/MAX681 product line was engineered specifically for compact, capacitor-based bipolar voltage generation in space- and cost-constrained analog systems - targeting handheld instrumentation and embedded signal-chain power.

FAQ

What is the maximum continuous output current supported by the MAX680CSA?

The MAX680CSA delivers up to 10mA per output rail (V+ and V−) under typical conditions (VCC = +5V, TA = +25°C). At 10mA load on V+, output droop is ~1.5V due to 150Ω source resistance; at 10mA on V−, droop is ~0.9V (90Ω). Combined loading must account for V− drawing current from V+, so total effective load on the positive pump is IL+ + IL−. The MAX680CSA datasheet specifies 75mA absolute max V+ current, but sustained operation above 10mA per rail degrades regulation and increases ripple significantly.

Can the MAX680CSA operate from a 3V lithium battery?

Yes, the MAX680CSA supports input voltages from +2.0V to +6.0V, making it fully compatible with 3V lithium coin cells and alkaline batteries. At VCC = +3V, it generates approximately ±6V (no-load), matching common low-voltage analog requirements. Quiescent current remains below 1mA, preserving battery life. However, output droop increases at lower VCC due to higher effective source resistance - e.g., RS+ rises to ~180Ω at VCC = +2.8V - so load current must be scaled accordingly to maintain target rail voltages.

Does the MAX680CSA require external timing components?

No, the MAX680CSA includes a fully integrated 8kHz oscillator - no external resistors, capacitors, or crystals are needed for clock generation. This simplifies design, improves reliability, and ensures consistent switching frequency across temperature and supply variations. The fixed 8kHz frequency determines ripple characteristics and minimum recommended reservoir capacitance (e.g., 10µF yields ~30mVpp at 5mA); designers may not adjust frequency, but can optimize capacitor values and layout to meet specific noise targets.

How does output voltage droop behave under combined V+ and V− loading?

Because the negative pump draws power from V+, droop is coupled: V+ droop = (IL+ + IL−) × RS+, and V− droop = IL− × RS−. For example, with IL+ = 5mA and IL− = 5mA at +25°C, V+ drops ~1.5V (150Ω × 10mA) and V− drops ~0.45V (90Ω × 5mA), yielding V+ ≈ +8.5V and V− ≈ −9.55V. This interdependence means V− regulation degrades faster than V+ as IL− increases - accurate system-level modeling requires using the separate RS+ and RS− values provided in the MAX680CSA datasheet's Electrical Characteristics table.

Is the MAX680CSA pin-compatible with the MAX681 series?

No, the MAX680CSA is not pin-compatible with any MAX681 variant. MAX680 uses an 8-pin narrow SO package with dedicated C1+/C1−/C2+/C2− pins for external capacitors, while MAX681 uses a 14-pin DIP/SO with different pinout and internal capacitors. Pin functions, counts, and physical layout differ fundamentally - PCB redesign and schematic updates are required to substitute between them. The MAX680CSA and MAX681CPD serve the same functional purpose but represent distinct hardware implementations with no mechanical or electrical interchangeability.