LTC3260EMSE

Part: LTC3260EMSE — Linear Technology (Analog Devices)

Type: Low Noise Dual Supply Inverting Charge Pump with Positive and Negative LDO Regulators

Description: 4.5–32 V input inverting charge pump (VOUT = –VIN, up to 100 mA) with independent 50 mA positive and 50 mA negative low noise LDO regulators and 100 μA quiescent current in Burst Mode operation.

Operating Conditions:

• Supply voltage (VIN): 4.5–32 V
• Operating junction temperature: -40 to 125 °C (LTC3260EMSE; specifications guaranteed 0 to 85 °C, and assured by design/characterization over -40 to 125 °C)
• Oscillator frequency: 50 kHz to 500 kHz (programmable via RT)
• LDO+ output range: 1.2–32 V; LDO– output range: –32 to –1.2 V

Absolute Maximum Ratings:

• VIN, EN+, EN–, MODE: -0.3 V to 36 V
• LDO+: -16 V to 36 V
• VOUT, LDO–: -36 V to 0.3 V
• RT, ADJ+: -0.3 V to 6 V
• Operating junction temperature: -55 to 150 °C
• Storage temperature: -65 to 150 °C
• VOUT, LDO+, LDO– short-circuit duration: indefinite

Key Specs:

• VIN UVLO threshold: 3.8 V typ rising, 3.6 V typ falling (VIN = 12 V)
• VIN quiescent current: 2 μA typ in shutdown; 100 μA typ in Burst Mode with both LDOs on and no load; 3.5 mA typ in constant frequency mode (MODE = 0 V)
• Charge pump output: –0.94·VIN in Burst Mode, –VIN in constant frequency mode
• Charge pump output impedance: 32 Ω typ (MODE = 0 V, RT = GND)
• Oscillator frequency: 500 kHz typ (450–550 kHz) with RT = GND
• VOUT short-circuit current: 160 mA typ (100–250 mA)
• ADJ+ reference: 1.200 V typ (1.176–1.224 V); ADJ– reference: –1.200 V typ (–1.224 to –1.176 V)
• LDO+ dropout: 400 mV typ, 800 mV max at 50 mA; LDO– dropout: 200 mV typ, 500 mV max at 50 mA
• LDO output noise: 100 μVRMS typ for both LDOs (CBYP = 10 nF)
• LDO short-circuit current: 100 mA typ for both LDOs

Features:

• Inverting charge pump generates –VIN, with up to 100 mA output current
• Low noise negative LDO post regulator (50 mA max)
• Low noise independent positive LDO regulator (50 mA max)
• Burst Mode operation for low quiescent current
• Programmable 50 kHz–500 kHz oscillator
• Stable with ceramic capacitors
• Short-circuit and thermal protection
• Adjustable LDO output voltages via external resistor dividers

Applications:

• Low noise bipolar/inverting supplies
• Industrial/instrumentation low noise bias generators
• Portable medical equipment
• Portable instruments

Package:

• 16-Lead Plastic MSOP, thermally enhanced with exposed pad (LTC3260EMSE)
• 14-Lead (4 mm × 3 mm) Plastic DFN (other variants)

• n Low Noise Bipolar/Inverting Supplies
• n Industrial/Instrumentation Low Noise Bias Generators
• n Portable Medical Equipment
• n Portable Instruments

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors.

Note 2: The LTC3260 is tested under pulsed load conditions such that T J ≈ T A . The LTC3260E is guaranteed to meet specifications from 0°C to 85°C junction temperature. Specifications over the -40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3260I is guaranteed over the -40°C to 125°C operating junction temperature range, the LTC3260H is guaranteed over the -40°C to 150°C operating junction temperature range and the LTC3260MP is tested and guaranteed over the full -55°C to 150°C operating junction temperature range. Note that the maximum ambient temperature consistent with The junction temperature (T J , in °C) is calculated from the ambient temperature (T A , in °C) and power dissipation (P D , in Watts) according to the formula:

$$T_J = T_A + (P_D \bullet \theta_{JA}),$$

where θ JA = 43°C/W is the package thermal impedance.

Note 3: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperatures will exceed 150°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may result in device degradation or failure.

The LTC3260 has built-in short-circuit current limit as well as overtemperature protection. During a short-circuit condition, the part automatically limits its output current to approximately 160mA. If the junction temperature exceeds approximately 175°C the thermal shutdown circuitry disables current delivery to the output. Once the junction temperature drops back to approximately 165°C current delivery to the output is resumed. When thermal protection is active the junction temperature is beyond the specified operating range. Thermal protection is intended for momentary overload conditions outside normal operation. Continuous operation above the specified maximum operating junction temperature may impair device reliability.

Low Noise ±12V Power Supply from a Single-Ended 15V Input Supply (Frequency = 200kHz)