ADP2108-2.5-EVALZ

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Compact, 600 mA, 3 MHz, Step-Down DC-to-DC Converter Data Sheet ADP2108 Rev. G Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2008–2012 Analog Devices, Inc. All rights reserved.

FEATURES

Peak efficiency: 95%

3 MHz fixed frequency operation

Typical quiescent current: 18 μA Maximum load current: 600 mA Input voltage: 2.3 V to 5.5 V Uses tiny multilayer inductors and capacitors Current mode architecture for fast load and line transient response 100% duty cycle low dropout mode Internal synchronous rectifier Internal compensation Internal soft start Current overload protection Thermal shutdown protection Shutdown supply current: 0.2 μA Available in 5-ball WLCSP 5-lead TSOT Supported by ADIsimPower™ design tool

APPLICATIONS

PDAs and palmtop computers Wireless handsets Digital audio, portable media players Digital cameras, GPS navigation units GENERAL DESCRIPTION The ADP2108 is a high efficiency, low quiescent current step- down dc-to-dc converter manufactured in two different packages. The total solution requires only three tiny external components. It uses a proprietary, high speed current mode, constant frequency PWM control scheme for excellent stability and transient response. To ensure the longest battery life in portable applications, the ADP2108 has a power save mode that reduces the switching frequency under light load conditions. The ADP2108 runs on input voltages of 2.3 V to 5.5 V, which allows for single lithium or lithium polymer cell, multiple alkaline or NiMH cell, PCMCIA, USB, and other standard power sources. The maximum load current of 600 mA is achievable across the input voltage range. The ADP2108 is available in fixed output voltages of 3.3 V, 3.0 V, versions include an internal power switch and synchronous rect- ifier for minimal external part count and high efficiency. The ADP2108 has an internal soft start and is internally compensated. During logic controlled shutdown, the input is disconnected from the output and the ADP2108 draws less than 1 μA from the input source. Other key features include undervoltage lockout to prevent deep battery discharge and soft start to prevent input current over- shoot at startup. The ADP2108 is available in 5-ball WLCSP and 5-lead TSOT packages. The ADP2109 provides the same features and operations as the ADP2108 and has the additional function of a discharge switch in the WLCSP package. TYPICAL APPLICATIONS CIRCUIT Figure 1. 1.0V TO 3.3V 10µF 1µH ON OFF GND 4.7µF 07375-003 VIN SW FBEN 2.3V TO 5.5V ADP2108

Rev. G | Page 2 of 20 TABLE OF CONTENTS

REVISION HISTORY

6/12—Rev. F to Rev. G 1/12—Rev. E to Rev. F 10/10—Rev. D to Rev. E 1/10—Rev. C to Rev. D 4/09—Rev. B to Rev. C 2/09—Rev. A to Rev. B 11/08—Rev. 0 to Rev. A 9/08—Revision 0: Initial Version

Rev. G | Page 3 of 20 SPECIFICATIONS VIN = 3.6 V, VOUT = 1.8 V, TJ = −40°C to +125°C for minimum/maximum specifications, and TA = 25°C for typical specifications, unless otherwise noted.1 Table 1. Parameter Test Conditions/Comments Min Typ Max Unit INPUT CHARACTERISTICS Input Voltage Range 2.3 5.5 V Undervoltage Lockout Threshold VIN rising 2.3 V VIN falling 2.05 2.15 2.25 V OUTPUT CHARACTERISTICS Output Voltage Accuracy PWM mode −2 +2 % VIN = 2.3 V to 5.5 V, PWM mode −2.5 +2.5 % POWER SAVE MODE TO PWM CURRENT THRESHOLD 85 mA PWM TO POWER SAVE MODE CURRENT THRESHOLD 80 mA INPUT CURRENT CHARACTERISTICS DC Operating Current ILOAD = 0 mA, device not switching 18 30 µA Shutdown Current EN = 0 V, TA = TJ = −40°C to +125°C 0.2 1.0 µA SW CHARACTERISTICS SW On Resistance (WLCSP) PFET 320 mΩ NFET 300 mΩ SW On Resistance (TSOT) PFET 380 mΩ NFET 260 mΩ Current Limit PFET switch peak current limit 1100 1300 1500 mA ENABLE CHARACTERISTICS EN Input High Threshold 1.2 V EN Input Low Threshold 0.4 V EN Input Leakage Current EN = 0 V, 3.6 V −1 0 +1 µA OSCILLATOR FREQUENCY ILOAD = 200 mA 2.5 3.0 3.5 MHz START-UP TIME 550 µs THERMAL CHARACTERISTICS Thermal Shutdown Threshold 150 °C Thermal Shutdown Hysteresis 20 °C 1 All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).

J is within the specified temperature limits. θJA is specified for a device mounted on a JEDEC 2S2P PCB. Table 3. Thermal Resistance

Figure 28. Typical PWM Waveform, 200 mA

Figure 29. Functional Block Diagram and regulates an output voltage down to 1.0 V. and enters an idle mode, which improves conversion efficiency. voltage by adjusting the peak inductor current threshold. load current is below the power save mode current threshold. is optimized for excellent efficiency over all load currents.

Rev. G | Page 12 of 20 SHORT-CIRCUIT PROTECTION The ADP2108 includes frequency foldback to prevent output current runaway on a hard short. When the voltage at the feedback pin falls below half the target output voltage, indicat- ing the possibility of a hard short at the output, the switching frequency is reduced to half the internal oscillator frequency. The reduction in the switching frequency allows more time for the inductor to discharge, preventing a runaway of output current. UNDERVOLTAGE LOCKOUT To protect against battery discharge, undervoltage lockout (UVLO) circuitry is integrated on the ADP2108. If the input voltage drops below the 2.15 V UVLO threshold, the ADP2108 shuts down, and both the power switch and the synchronous rectifier turn off. When the voltage rises above the UVLO thresh- old, the soft start period is initiated, and the part is enabled. THERMAL PROTECTION In the event that the ADP2108 junction temperature rises above 150°C, the thermal shutdown circuit turns off the converter. Extreme junction temperatures can be the result of high current operation, poor circuit board design, or high ambient temperature. A 20°C hysteresis is included so that when thermal shutdown occurs, the ADP2108 does not return to operation until the on-chip temperature drops below 130°C. When coming out of thermal shutdown, soft start is initiated. SOFT START The ADP2108 has an internal soft start function that ramps the output voltage in a controlled manner upon startup, thereby limiting the inrush current. This prevents possible input voltage drops when a battery or a high impedance power source is connected to the input of the converter. After the EN pin is driven high, internal circuits start to power up. The time required to settle after the EN pin is driven high is called the power-up time. After the internal circuits are powered up, the soft start ramp is initiated and the output capacitor is charged linearly until the output voltage is in regulation. The time required for the output voltage to ramp is called the soft start time. Start-up time in the ADP2108 is the measure of when the output is in regulation after the EN pin is driven high. Start-up time consists of the power-up time and the soft start time. CURRENT LIMIT The ADP2108 has protection circuitry to limit the amount of positive current flowing through the PFET switch and the synchronous rectifier. The positive current limit on the power switch limits the amount of current that can flow from the input to the output. The negative current limit prevents the inductor current from reversing direction and flowing out of the load. 100% DUTY OPERATION With a drop in VIN or with an increase in ILOAD, the ADP2108 reaches a limit where, even with the PFET switch on 100% of the time, VOUT drops below the desired output voltage. At this limit, the ADP2108 smoothly transitions to a mode where the PFET switch stays on 100% of the time. When the input conditions change again and the required duty cycle falls, the ADP2108 immediately restarts PWM regulation without allowing over- shoot on VOUT.

The ADP2108 is supported by ADIsimPower design tool set. inductors are shown in Table 6. fSW is the switching frequency. through the inductor, which has an associated internal DCR. Table 6. Suggested 1.0 μH Inductors each with different behavior over temperature and applied voltage. CEFF is the effective capacitance at the operating voltage. TEMPCO is the worst-case capacitor temperature coefficient. TOL is the worst-case component tolerance. over −40°C to +125°C is assumed to be 15% for an X5R dielectric. COUT is 9.2 μF at 1.8 V, as shown in Figure 30. behavior of the capacitors be evaluated for each application.

Figure 30. Typical Capacitor Performance temperature and dc bias effects, i s 7 µF. Table 7. Suggested 10 μF Capacitors recommended capacitors is shown in Table 8. Table 8. Suggested 4.7 μF Capacitors which reduces thermal constraints. recovers when the junction temperature falls below 130°C. TJ is the junction temperature. TA is the ambient temperature. TR is the rise in temperature of the package. ambient temperature of the package. PD is the power dissipation in the package.

• Place the inductor, input capacitor, and output capacitor close to the IC using short tracks. These components carry high switching frequencies, and large tracks act as antennas.
• Route the output voltage path away from the inductor and SW node to minimize noise and magnetic interference.
• Maximize the size of ground metal on the component side to help with thermal dissipation.
• Use a ground plane with several vias connecting to the com- ponent side ground to further reduce noise interference on sensitive circuit nodes. 0 1 2 3 4 5 6 07375-007DC BIAS VOLTAGE (V) CAPACITANCE (µF)

Figure 36. 5-Ball Wafer Level Chip Scale Package [WLCSP] Figure 37. 5-Lead Thin Small Outline Transistor Package [TSOT]

0.50 BSC

THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS.

0.95 BSC

0.10 MAX

0.70 MIN

2.90 BSC

Rev. G | Page 17 of 20 ORDERING GUIDE Model1 Temperature Range Output Voltage (V) Package Description Package Option Branding ADP2108ACBZ-1.0-R7 −40°C to +125°C 1.0 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LA6 ADP2108ACBZ-1.1-R7 −40°C to +125°C 1.1 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LA7 ADP2108ACBZ-1.2-R7 −40°C to +125°C 1.2 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LA8 ADP2108ACBZ-1.3-R7 −40°C to +125°C 1.3 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LA9 ADP2108ACBZ-1.5-R7 −40°C to +125°C 1.5 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAA ADP2108ACBZ-1.8-R7 −40°C to +125°C 1.8 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAD ADP2108ACBZ-1.82-R7 −40°C to +125°C 1.82 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAE ADP2108ACBZ-2.3-R7 −40°C to +125°C 2.3 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAF ADP2108ACBZ-2.5-R7 −40°C to +125°C 2.5 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAG ADP2108ACBZ-3.0-R7 −40°C to +125°C 3.0 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LD9 ADP2108ACBZ-3.3-R7 −40°C to +125°C 3.3 5-Ball Wafer Level Chip Scale Package [WLCSP] CB-5-3 LAH ADP2108AUJZ-1.0-R7 −40°C to +125°C 1.0 5-Lead Small Outline Package [TSOT] UJ-5 LA6 ADP2108AUJZ-1.1-R7 −40°C to +125°C 1.1 5-Lead Small Outline Package [TSOT] UJ-5 LA7 ADP2108AUJZ-1.2-R7 −40°C to +125°C 1.2 5-Lead Small Outline Package [TSOT] UJ-5 LA8 ADP2108AUJZ-1.3-R7 −40°C to +125°C 1.3 5-Lead Small Outline Package [TSOT] UJ-5 LA9 ADP2108AUJZ-1.5-R7 −40°C to +125°C 1.5 5-Lead Small Outline Package [TSOT] UJ-5 LAA ADP2108AUJZ-1.8-R7 −40°C to +125°C 1.8 5-Lead Small Outline Package [TSOT] UJ-5 LAD ADP2108AUJZ-1.82-R7 −40°C to +125°C 1.82 5-Lead Small Outline Package [TSOT] UJ-5 LAE ADP2108AUJZ-2.3-R7 −40°C to +125°C 2.3 5-Lead Small Outline Package [TSOT] UJ-5 LAF ADP2108AUJZ-2.5-R7 −40°C to +125°C 2.5 5-Lead Small Outline Package [TSOT] UJ-5 LAG ADP2108AUJZ-3.0-R7 −40°C to +125°C 3.0 5-Lead Small Outline Package [TSOT] UJ-5 LD9 ADP2108AUJZ-3.3-R7 −40°C to +125°C 3.3 5-Lead Small Outline Package [TSOT] UJ-5 LAH ADP2108-1.0-EVALZ 1.0 Evaluation Board for 1.0 V [WLCSP] ADP2108-1.1-EVALZ 1.1 Evaluation Board for 1.1 V [WLCSP] ADP2108-1.2-EVALZ 1.2 Evaluation Board for 1.2 V [WLCSP] ADP2108-1.3-EVALZ 1.3 Evaluation Board for 1.3 V [WLCSP] ADP2108-1.5-EVALZ 1.5 Evaluation Board for 1.5 V [WLCSP] ADP2108-1.8-EVALZ 1.8 Evaluation Board for 1.8 V [WLCSP] ADP2108-1.82-EVALZ 1.82 Evaluation Board for 1.82 V [WLCSP] ADP2108-2.3-EVALZ 2.3 Evaluation Board for 2.3 V [WLCSP] ADP2108-2.5-EVALZ 2.5 Evaluation Board for 2.5 V [WLCSP] ADP2108-3.0-EVALZ 3.0 Evaluation Board for 3.0 V [WLCSP] ADP2108-3.3-EVALZ 3.3 Evaluation Board for 3.3 V [WLCSP] ADP2108UJZ-REDYKIT Evaluation Board for Fixed Output Voltage, 1.2 V and 3.3 V [TSOT] 1 Z = RoHS Compliant Part.

Rev. G | Page 18 of 20 NOTES

Rev. G | Page 19 of 20 NOTES

Rev. G | Page 20 of 20 NOTES ©2008–2012 Analog Devices, Inc. All ri ghts reserved. Trademarks and registered trademarks are the prop erty of their respective owners. D07375-0-6/12(G)