LM3686

ACTIVE

Step-Down DC-DC Converter with Integrated Post Linear Regulators System & Low-Noise Linear Reg.

Product details

Regulated outputs (#) 3 Configurability Factory programmable Vin (min) (V) 2.7 Vin (max) (V) 5.5 Iout (max) (A) 0.9 Step-up DC/DC converter 0 Step-down DC/DC converter 1 Step-down DC/DC controller 0 Step-up DC/DC controller 0 LDO 2 Iq (typ) (mA) 0.07 Rating Catalog Switching frequency (max) (kHz) 3400 Operating temperature range (°C) -30 to 85 Processor supplier Generic Processor name Generic Shutdown current (ISD) (typ) (µA) 2.5 Switching frequency (typ) (kHz) 3000
Regulated outputs (#) 3 Configurability Factory programmable Vin (min) (V) 2.7 Vin (max) (V) 5.5 Iout (max) (A) 0.9 Step-up DC/DC converter 0 Step-down DC/DC converter 1 Step-down DC/DC controller 0 Step-up DC/DC controller 0 LDO 2 Iq (typ) (mA) 0.07 Rating Catalog Switching frequency (max) (kHz) 3400 Operating temperature range (°C) -30 to 85 Processor supplier Generic Processor name Generic Shutdown current (ISD) (typ) (µA) 2.5 Switching frequency (typ) (kHz) 3000
DSBGA (YZR) 12 3.9375 mm² 2.25 x 1.75
  • DC-DC Regulator
    • VOUT_DCDC = 1.2 V to 2.5 V
    • 600-mA Maximum ILOAD
    • 3-MHz Typical PWM Fixed Switching Frequency
    • Automatic PFM/PWM Mode Switching
    • Internal Synchronous Rectification
    • Internal Soft Start
  • Dual-Rail Linear Regulator: LILO
    • Load Transients < 50-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LILO = 0.7 V to 2 V
    • 70-µA Typical IQ and 300-mA Maximum ILOAD
  • Linear Regulator: LDO
    • Load Transients < 80-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LDO = 1.5 V to 3.3 V
    • 50-µA Typical IQ and 350-mA Maximum ILOAD
  • Combined Global Features
    • VBATT ≥ Maximum (VOUT_LILO + 1.5 V, 2.7 V)
    • Operates From a Single Li-Ion Cell or 3-Cell NiMH/NiCd Batteries
    • 100-µA IQ and 900-mA Maximum ILOAD
  • DC-DC Regulator
    • VOUT_DCDC = 1.2 V to 2.5 V
    • 600-mA Maximum ILOAD
    • 3-MHz Typical PWM Fixed Switching Frequency
    • Automatic PFM/PWM Mode Switching
    • Internal Synchronous Rectification
    • Internal Soft Start
  • Dual-Rail Linear Regulator: LILO
    • Load Transients < 50-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LILO = 0.7 V to 2 V
    • 70-µA Typical IQ and 300-mA Maximum ILOAD
  • Linear Regulator: LDO
    • Load Transients < 80-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LDO = 1.5 V to 3.3 V
    • 50-µA Typical IQ and 350-mA Maximum ILOAD
  • Combined Global Features
    • VBATT ≥ Maximum (VOUT_LILO + 1.5 V, 2.7 V)
    • Operates From a Single Li-Ion Cell or 3-Cell NiMH/NiCd Batteries
    • 100-µA IQ and 900-mA Maximum ILOAD

The LM3686 is a step-down DC-DC converter with a very low-dropout linear regulator and a low-noise linear regulator optimized for powering ultra-low voltage circuits. It provides three outputs with combined load current up to 900 mA over an input voltage range from 2.7 V to 5.5 V.

The device offers superior features and performance for many applications. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During full-power operation, a fixed-frequency 3 MHz (typical), PWM mode drives loads from approximately 70 mA to 600 mA maximum. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 28 μA (typical) at light load and system standby. Internal synchronous rectification provides high efficiency.

For all available packages, see the orderable addendum at the end of the data sheet.

All trademarks are the property of their respective owners.

Three enable (EN_x) pins allow the separate operation of either the DC-DC, post-regulation linear regulator, or the linear regulator alone. If the DC-DC is not enabled during start-up of the post-regulation linear regulator, a parallel small-pass transistor supplies the linear regulator from VBATT with maximal 50 mA. In the combined operation where both enables are raised together, the small-pass transistor is deactivated and the big pass transistor provides 350 mA output current. In shutdown mode (EN_x pins pulled low), the device turns off and reduces battery consumption to 2.5 μA (typical).

The LM3686 is available in a 12-pin DSBGA package. A high-switching frequency of 3 MHz (typical) allows the use of a few tiny surface-mount components. Only six external surface-mount components, an inductor and five ceramic capacitors, are required to establish a 15.66 mm2 total solution size.

The LM3686 is a step-down DC-DC converter with a very low-dropout linear regulator and a low-noise linear regulator optimized for powering ultra-low voltage circuits. It provides three outputs with combined load current up to 900 mA over an input voltage range from 2.7 V to 5.5 V.

The device offers superior features and performance for many applications. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During full-power operation, a fixed-frequency 3 MHz (typical), PWM mode drives loads from approximately 70 mA to 600 mA maximum. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 28 μA (typical) at light load and system standby. Internal synchronous rectification provides high efficiency.

For all available packages, see the orderable addendum at the end of the data sheet.

All trademarks are the property of their respective owners.

Three enable (EN_x) pins allow the separate operation of either the DC-DC, post-regulation linear regulator, or the linear regulator alone. If the DC-DC is not enabled during start-up of the post-regulation linear regulator, a parallel small-pass transistor supplies the linear regulator from VBATT with maximal 50 mA. In the combined operation where both enables are raised together, the small-pass transistor is deactivated and the big pass transistor provides 350 mA output current. In shutdown mode (EN_x pins pulled low), the device turns off and reduces battery consumption to 2.5 μA (typical).

The LM3686 is available in a 12-pin DSBGA package. A high-switching frequency of 3 MHz (typical) allows the use of a few tiny surface-mount components. Only six external surface-mount components, an inductor and five ceramic capacitors, are required to establish a 15.66 mm2 total solution size.

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* Data sheet LM3686 Step-Down DC-DC Converter With Integrated Post Linear Regulators System And Low-Noise Linear Regulator datasheet (Rev. F) PDF | HTML 23 Nov 2016
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
EVM User's guide AN-1886 LM3686 Evaluation Board (Rev. A) 30 Apr 2013

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