Datasheet

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High Voltage, 1.2 MHz/600 kHz, 800 mA,

Low Quiescent Current Buck Regulator

Data Sheet

ADP2370/ADP2371

Rev. C

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FEATURES

Input voltage range: 3.2 V to 15 V, output current: 800 mA

Quiescent current < 14 µA in power saving mode (PSM)

>90% efficiency

Force PWM pin (SYNC), 600 kHz/1.2 MHz frequency pin

(FSEL)

Fixed outputs: 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.0 V, 3.3 V, 5 V,

and adjustable option

100% duty cycle capability

Initial accuracy: ±1%

Low shutdown current: <1.2 µA

Quick output discharge (QOD) option

Synchronizable to an external clock

8-lead, 0.75 mm × 3 mm × 3 mm LFCSP (QFN) package

Supported by ADIsimPower design tool

APPLICATIONS

Portable and battery-powered equipment

Automatic meter readers (WSN)

Point of sales and transaction processing instruments

Medical instruments

Medium format display tablets and pads

TYPICAL APPLICATION CIRCUIT

ADP2370/

ADP2371

FSEL

POWER GOOD

OUT

= 3.3V

= 6V

10µF

OUT

10µF

AGND

(EXPOSED PAD)

VIN

SYNC

OFF

1.2MHz

600kHz

PGND

09531-001

Figure 1.

GENERAL DESCRIPTION

The ADP2370/ADP2371 are high efficiency, low quiescent current,

800 mA buck (step-down) dc-to-dc converters in small 8-lead,

3 mm × 3 mm LFCSP (QFN) packages. The total solution requires

only three tiny external components.

The buck regulator uses a proprietary high speed current mode,

constant frequency PWM control scheme for excellent stability

and transient response. The need for an external rectifier is elimi-

nated by using a high efficiency synchronous rectifier architecture.

To ensure the longest battery life in portable applications, the

ADP2370/ADP2371 employ a power saving variable frequency

mode that reduces the switching frequency under light load

conditions. The ADP2370/ADP2371 operate from input voltages

of 3.2 V to 15 V allowing the use of multiple alkaline/NiMH,

lithium cells, or other standard power sources.

The ADP2370/ADP2371 offer multiple options for setting the

operational frequency. The ADP2370/ADP2371 can be synchro-

nized to a 600 kHz to 1.2 MHz external clock or it can be forced

to operate at 600 kHz or 1.2 MHz via the FSEL pin. The ADP2370/

ADP2371 can be forced to operate in PWM mode (FPWM) when

noise considerations are more important than efficiency.

A power-good output is available to indicate when the output

voltage is below 92% of its nominal value.

The ADP2371 is identical to the ADP2370 except that the

ADP2371 includes the addition of an integrated switched

resistor, quick output discharge function (QOD) that auto-

matically discharges the output when the device is disabled.

Both devices include an internal power switch and a synchronous

rectifier for minimal external part count and high efficiency.

The ADP2370/ADP2371 also include internal soft start and

internal compensation for ease of use.

During a logic controlled shutdown, the input is disconnected

from the output and the regulator draws less than 1.2 μA from

the input source. Other key features include undervoltage lockout

to prevent deep battery discharge and soft start to prevent input

overcurrent at startup. Short-circuit protection and thermal over-

load protection circuits prevent damage under adverse conditions.

The ADP2370/ADP2371 each use one 0805 capacitor, one 1206

capacitor, and one 4 mm × 4 mm inductor. The total solution

size is about 53 mm

resulting in a very small footprint solution

to meet a variety of portable applications.

Summary of content (32 pages)

PAGE 1
Data Sheet High Voltage, 1.2 MHz/600 kHz, 800 mA, Low Quiescent Current Buck Regulator ADP2370/ADP2371 FEATURES TYPICAL APPLICATION CIRCUIT VIN = 6V CIN 10µF POWER GOOD VIN 1.2MHz 600kHz ON ADP2370/ ADP2371 1 8 FSEL 2 7 EN 6 3 OFF PGND SW PG VOUT = 3.3V COUT 10µF AGND (EXPOSED PAD) SYNC 4 5 FB 09531-001 Input voltage range: 3.2 V to 15 V, output current: 800 mA Quiescent current < 14 µA in power saving mode (PSM) >90% efficiency Force PWM pin (SYNC), 600 kHz/1.
PAGE 2
ADP2370/ADP2371 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Undervoltage Lockout ............................................................... 22 Applications ....................................................................................... 1 Thermal Protection .................................................................... 22 Typical Application Circuit .............................................
PAGE 3
Data Sheet ADP2370/ADP2371 SPECIFICATIONS VIN = VOUT + 1 V or 3.2 V, whichever is greater, EN = VIN, IOUT = 100 mA, CIN = 10 μF, COUT = 10 µF, TA = 25°C for typical specifications, TJ = −40°C to +125°C for minimum/maximum specifications, unless otherwise noted. Table 1.
PAGE 4
ADP2370/ADP2371 Parameter OSCILLATOR Oscillator Frequency Data Sheet Symbol Test Conditions/Comments Min Typ Max Unit fOSC FSEL = VIN, 3.2 V ≤ VIN ≤ 15 V FSEL = 0 V, 3.2 V ≤ VIN ≤ 15 V FSEL = 0 V, 3.2 V ≤ VIN ≤ 15 V FSEL = VIN, 3.2 V ≤ VIN ≤ 15 V 1.0 500 400 0.8 1.2 600 1.4 700 800 1.6 MHz kHz kHz MHz 3.2 V ≤ VIN ≤ 15 V 3.2 V ≤ VIN ≤ 15 V 3.2 V ≤ VIN ≤ 15 V VIN (1.2 MHz), 3.2 V ≤ VIN ≤ 5 V, FSEL = VIN VIN (1.2 MHz), 5 V ≤ VIN ≤ 15 V, FSEL = VIN SYNC = 0 V or SYNC = VIN 3.2 V ≤ VIN ≤ 15 V 1.
PAGE 5
Data Sheet ADP2370/ADP2371 RECOMMENDED SPECIFICATIONS: CAPACITORS Table 2. Parameter MINIMUM INPUT and OUTPUT CAPACITANCE 1 CAPACITOR ESR 1 Symbol CMIN RESR Test Conditions/Comments TA = −40°C to +125°C TA = −40°C to +125°C Min 6.5 1 Typ 10 Max 10 Unit µF mΩ The minimum input and output capacitance should be greater than 7 μF over the full range of operating conditions.
PAGE 6
ADP2370/ADP2371 Data Sheet ABSOLUTE MAXIMUM RATINGS Table 3. Parameter VIN to PGND and Ground Plane SW to PGND and Ground Plane FB to PGND and Ground Plane EN to PGND and Ground Plane PG to PGND and Ground Plane SYNC to PGND and Ground Plane FSEL to PGND and Ground Plane Temperature Range Storage Operating Ambient Operating Junction Soldering Conditions Rating −0.3 V to +17 V −0.7 V to VIN + 0.3 V −0.3 V to +6 V −0.3 V to +17 V −0.3 V to +17 V −0.3 V to +17 V −0.
PAGE 7
Data Sheet ADP2370/ADP2371 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ADP2370/ADP2371 VIN 1 EN 3 SYNC 4 8 PGND TOP VIEW (Not to Scale) 7 SW 6 PG 5 FB NOTES 1. THE EXPOSED PAD ON THE BOTTOM OF THE PACKAGE ENHANCES THE THERMAL PERFORMANCE AND IS ELECTRICALLY CONNECTED TO GROUND INSIDE THE PACKAGE. THE EXPOSED PAD MUST BE CONNECTED TO THE GROUND PLANE ON THE CIRCUIT BOARD FOR PROPER OPERATION. 09531-002 FSEL 2 Figure 2. Pin Configuration Table 5. Pin Function Descriptions Pin No.
PAGE 8
ADP2370/ADP2371 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS BUCK OUTPUT Using recommended inductor values, IOUT = 10 mA, CIN = COUT = 10 µF, automatic PSM/PWM mode, TA = 25°C, unless otherwise noted. 0.65 1.30 25 0.63 1.26 15 10 4 5 1.22 0.59 1.18 1.16 0.57 6 7 8 10 9 11 12 13 14 15 1.12 0.55 1.10 16 3 5 7 9 11 13 15 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Figure 3. Quiescent Supply Current vs. Input Voltage, Nonswitching, Different Temperatures Figure 6.
PAGE 9
Data Sheet ADP2370/ADP2371 3.40 1.25 3.35 1.21 1.19 0.1mA 1mA 5mA 10mA 50mA 100mA 300mA 800mA 1.15 –40 3.25 3.8V 4.55V 6.05V 7.30V 10.55V 12.05V 15.05V 3.20 3.15 –5 25 85 125 TEMPERATURE (°C) 3.10 09531-009 1.17 3.30 0.1 1 10 100 1000 LOAD (mA) 09531-012 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.23 Figure 12. Load Regulation, VOUT = 3.3 V Figure 9. Output Voltage vs. Temperature, VOUT = 1.2 V, VIN = 4 V, Different Loads 1.90 3.40 0.1mA 1mA 5mA 10mA 50mA 100mA 300mA 800mA 1.
PAGE 10
ADP2370/ADP2371 Data Sheet 1.25 1.90 1.24 1.22 1.21 1.20 1.19 0.1mA 1mA 5mA 10mA 50mA 100mA 300mA 800mA 1.17 1.16 1.15 3 1.80 1.75 5 7 9 11 13 15 INPUT VOLTAGE (V) 1.24 90 1.23 80 1.22 70 EFFICIENCY (%) 100 1000 1.21 1.20 3.20V 3.95V 5.45V 7.20V 9.95V 11.95V 15.20V 60 50 3.80V 4.55V 6.05V 7.30V 10.55V 12.05V 15.05V 40 30 20 10 1.16 1 10 100 1000 LOAD (mA) 0 0.01 09531-016 1.15 0.1 0.10 1.0 10 100 1000 LOAD (mA) 09531-019 OUTPUT VOLTAGE (V) 100 1.
PAGE 11
ADP2370/ADP2371 100 100 90 90 80 80 70 70 EFFICIENCY (%) 60 50 5.4V 6.0V 7.2V 9.0V 10.8V 12.8V 15.0V 40 30 20 10 100 1000 90 90 80 80 70 70 EFFICIENCY (%) 100 50 –40°C –5°C +25°C +85°C +125°C 40 30 20 10 100 1000 LOAD (mA) Figure 22. Efficiency vs. Load Current, VOUT = 5.0 V, Different Temperatures 0 0.01 90 80 80 70 70 EFFICIENCY (%) 90 50 40 3.20V 3.95V 5.50V 7.20V 9.95V 12.45V 15.20V 10 0 0.01 0.10 1.0 1.
PAGE 12
ADP2370/ADP2371 Data Sheet 90 VIN 85 80 600kHz EFFICIENCY (%) 75 INDUCTOR CURRENT 1.2MHz 70 1 65 60 VOUT 55 2 3 09531-030 50 45 0.1 100 10 1 1000 LOAD (mA) CH1 500mA Ω BW CH2 20.0mV CH3 1.00V BW 09531-027 40 0.01 Figure 27. Efficiency vs. Load Current, Different Switching Frequency, VOUT = 1.8 V, VIN = 9 V B M10.0µs A CH3 W T 4.56V 11.0% Figure 30. Line Transient, VOUT = 1.2 V, PSM Mode, 100 mA, VIN1 = 4 V to 5 V, 2 μs Rise Time, CIN = 3.
PAGE 13
Data Sheet ADP2370/ADP2371 LOAD CURRENT VIN 1 INDUCTOR CURRENT VOUT 2 VOUT 09531-033 1 CH1 200mA Ω BW CH2 10.0mV CH3 1.00V BW B M10.0µs A CH3 W T 3 6.78V 11.40% Figure 33. Line Transient, VOUT = 3.3 V, PWM Mode, 800 mA, VIN1 = 6 V to 7 V, 2 μs Rise Time, CIN = 3.3 μF 09531-036 INDUCTOR CURRENT 2 CH1 500mA Ω BW CH2 50.0mV CH3 500mA Ω BW B W M20.0µs A CH1 T 560mA 10.40% Figure 36. Load Transient, VOUT = 1.
PAGE 14
ADP2370/ADP2371 Data Sheet LOAD CURRENT LOAD CURRENT 1 1 VOUT VOUT 2 2 09531-039 3 CH1 200mA Ω BW CH2 50.0mV CH3 200mA Ω BW B W M20.0µs A CH1 T 3 208mA 50.40% Figure 39. Load Transient, VOUT = 1.8 V,100 mA to 300 mA, Load Current Rise Time = 200 ns CH1 100mA Ω BW CH2 50.0mV CH3 200mA Ω BW B W M20.0µs A CH1 T 46.0mA 50.40% Figure 42. Load Transient, VOUT = 3.
PAGE 15
Data Sheet ADP2370/ADP2371 LOAD CURRENT LOAD CURRENT 1 1 VOUT 2 VOUT 2 INDUCTOR CURRENT CH1 500mA Ω BW CH2 100mV CH3 500mA Ω BW B W M40.0µs A CH1 T 3 320mA 72.00% Figure 45. Load Transient, VOUT = 1.2 V, 10 mA to 800 mA, Load Current Rise Time = 200 ns, VIN = 5 V 09531-048 3 09531-045 INDUCTOR CURRENT CH1 500mA Ω BW CH2 100mV CH3 500mA Ω BW B W M20.0µs A CH1 T 530mA 10.00% Figure 48.
PAGE 16
ADP2370/ADP2371 Data Sheet VIN LOAD CURRENT 1 1 VOUT VOUT 2 2 INDUCTOR CURRENT INDUCTOR CURRENT CH1 200mA Ω BW CH2 100mV CH3 200mA Ω BW B W M20.0µs A CH1 T 09531-054 09531-051 3 3 CH2 2.00V BW CH1 5.00V BW CH3 200mA Ω BW 208mA 30.40% Figure 51. Load Transient, VOUT = 5 V, 100 mA to 300 mA, Load Current Rise Time = 200 ns, VIN = 8 V M100µs T A CH1 2.50V 10.00% Figure 54. Startup, VOUT = 3.3 V, 10 mA VIN VIN 1 1 VOUT VOUT 2 2 INDUCTOR CURRENT INDUCTOR CURRENT CH2 1.
PAGE 17
Data Sheet ADP2370/ADP2371 250 1 VOUT 2 INDUCTOR CURRENT 09531-057 3 CH1 5.00V BW CH2 500mV BW CH3 500mA Ω BW M100µs T A CH1 200 150 100 –40°C –5°C +25°C +85°C +125°C 50 0 2.50V 3 5 7 9 11 13 15 INPUT VOLTAGE (V) 10.00% Figure 57. Startup, VOUT = 1.2 V, 800 mA, VIN = 5 V 09531-060 PSM TO PWM THRESHOLD (mA) VIN Figure 60. PSM to PWM Mode Transition vs. Input Voltage, Different Temperatures 1200 VIN 1150 1 OC THRESHOLD (mA) 1100 2 INDUCTOR CURRENT 1050 1000 5.4V 7.2V 12.
PAGE 18
Data Sheet 0.05 0.025 0.04 0.020 RIPPLE VOLTAGE (V p-p) 0.03 3.2V 5.0V 9.0V 15V 0.02 0.015 4V 5V 9V 15V 0.010 0.005 0.01 0 100 200 300 400 500 600 700 800 LOAD CURRENT (mA) 0 09531-063 0 Figure 63. Output Ripple vs. Load Current, VOUT = 1.8 V, Different Input Voltages, Automatic Mode 0 200 300 400 500 600 700 800 LOAD CURRENT (mA) Figure 66. Output Ripple vs. Load Current, VOUT = 3.3 V, Different Input Voltages, Force PWM Mode 1.0 0.08 0.9 0.8 0.06 0.7 0.
PAGE 19
Data Sheet ADP2370/ADP2371 1.0 1.0 +125°C +85°C +25°C –5°C –40°C 0.9 0.8 0.7 0.6 0.6 RDSON (Ω) 0.7 0.5 0.4 0.4 0.3 0.2 0.2 0.1 0.1 0 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 +125°C +85°C +25°C –5°C –40°C 0.5 0.3 0 09531-069 RDSON (Ω) 0.8 3 4 5 6 7 INPUT VOLTAGE (V) Figure 69. PMOS RDSON vs. Input Voltage at 400 mA, Different Temperatures 8 9 10 09531-070 0.9 Figure 70. NMOS RDSON vs. Input Voltage at 400 mA, Different Temperatures Rev.
PAGE 20
ADP2370/ADP2371 Data Sheet THEORY OF OPERATION 5V VIN REG 1.2V VSW EN_PREC EN VIN STANDBY 1.0V P_ILIMIT 1.2A VIN VIN UVLO 2.95V RDSON × Kr IMIN N_ILIMIT 200mA Kr –0.5A – (PWM) VIN SW 0A – (PSM) RDSON × Kr PWM VIN CONTROL LOGIC ADP2371 ONLY SLOPE COMP ISLOPE PGND PSM 0.808V 0.8V SYNC H = FPWM L = PWM/PSM FSEL H = 1.2MHz L = 600kHz OSCILLATOR DEFAULT = 1.2MHz VOUT ÷ 2 FREQUENCY FOLDBACK FB 150°C 135°C THSD ICOMP PG VTOL VCOMP gM 0.8V 0.736V 0.
PAGE 21
Data Sheet ADP2370/ADP2371 The negative side of the comparator input voltage is set by the voltage control loop minus the slope compensation. When the high-side switch turns off, the low-side switch turns on for the remainder of the clock period. Figure 72 and Figure 73 illustrate how the output voltage and inductor current change with loads and transitions in and out of PSM operation. The output voltage ripple in PSM is ~40 mV p-p, and the ripple in PWM is <10 mV p-p.
PAGE 22
ADP2370/ADP2371 Data Sheet FEATURES DESCRIPTIONS PRECISION ENABLE UNDERVOLTAGE LOCKOUT The enable circuit of the ADP2370/ADP2371 minimizes the input current during shutdown and simultaneously provides an accurate enable threshold. When the enable input voltage is below 400 mV, the regulators are in shutdown mode and the supply current is typically 1.2 μA. As the enable input voltage rises above the standby enable threshold of 1.
PAGE 23
Data Sheet ADP2370/ADP2371 100% DUTY CYCLE The ADP2370/ADP2371 enter and exit 100% duty cycle smoothly. The control loop seeks the next clock cycle while the high-side switch is engaged. When this occurs, the clock signal is masked and the PMOS remains on. When the input voltage increases, the internal VCOMP node decreases its signal to the control loop; thus, the device stops skipping clock cycles and exits 100% duty cycle.
PAGE 24
ADP2370/ADP2371 Data Sheet SW 1 2 VOUT INDUCTOR CURRENT VOUT ENABLE 3 SYNC CH2 50.0mV BW M2.00µs A CH2 CH1 5.00V BW B CH3 200mA Ω BW CH4 5.00V W T 20.0% –57.0mV 09531-080 09531-079 4 PG 3 2 1 CH1 500mV BW CH3 5.00V BW Figure 79. SYNC Transient 800 kHz to 1.2 MHz CH2 1.00V BW M40.0µs T A CH3 3.40V 10.00% Figure 80. Typical PG Timing at Startup POWER GOOD VOUT The ADP2370/ADP2371 power-good (PG) output indicates the state of the monitored output voltage.
PAGE 25
Data Sheet ADP2370/ADP2371 APPLICATIONS INFORMATION ADIsimPower DESIGN TOOL OUTPUT CAPACITOR ADP2370/ADP2371 are supported by the ADIsimPower™ design tool set. ADIsimPower is a collection of tools that produce complete power designs optimized for a specific design goal. The tools enable the user to generate a full schematic, bill of materials, and calculate performance in minutes.
PAGE 26
ADP2370/ADP2371 Data Sheet To minimize errors in the output voltage caused by the bias current of the FB pin, maintain a value of R2 that is less than 250 kΩ. For example, when R2 and R3 each equal 250 kΩ, the output voltage is 1.6 V. The output voltage error introduced by the FB pin bias current is 2.5 mV, or 0.156%, assuming a typical FB pin bias current of 10 nA at 25°C. Switching Losses Note that in shutdown mode, the output is turned off and the divider current is zero.
PAGE 27
Data Sheet ADP2370/ADP2371 VIN = 6V CIN 10µF R1 10kΩ 1 8 2 7 FSEL ON EN 3 OFF SYNC 6 POWER GOOD PGND SW PG 6.8µH VOUT = 1.8V COUT 10µF R2 249kΩ AGND (EXPOSED PAD) 4 5 FB R3 200kΩ 09531-083 VIN ADP2370/ ADP2371 Figure 83. Typical Application, 600 kHz, Adjustable Output Table 6.
PAGE 28
ADP2370/ADP2371 Data Sheet CAPACITOR SELECTION Output Capacitor The ADP2370/ADP2371 are designed for operation with small, space-saving ceramic capacitors, but function with most commonly used capacitors provided that the effective series resistance (ESR) value is carefully considered. The ESR of the output capacitor affects stability of the control loop. A minimum output capacitance of 7 µF with an ESR of 10 mΩ or less is recommended to ensure stability of the ADP2370/ADP2371.
PAGE 29
Data Sheet ADP2370/ADP2371 THERMAL CONSIDERATIONS Table 8. Typical θJA Values 95 85 75 6400mm2 500mm2 100mm2 TJ MAX 65 55 45 35 25 0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 TOTAL POWER DISSIPATION (W) Figure 86. Junction Temperature vs. Power Dissipation, TA = 25°C 140 130 120 110 100 90 6400mm2 500mm2 100mm2 TJ MAX 80 70 60 50 0 The device is soldered to minimum size pin traces. 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.
PAGE 30
ADP2370/ADP2371 Data Sheet PCB LAYOUT CONSIDERATIONS 135 Improve heat dissipation from the package by increasing the amount of copper attached to the pins of the ADP2370/ ADP2371. However, as listed in Table 8, a point of diminishing returns is eventually reached, beyond which an increase in the copper size does not yield significant heat dissipation benefits.
PAGE 31
ADP2370/ADP2371 09531-091 Data Sheet 09531-092 Figure 91. PCB Layout, Top Figure 92. PCB Layout, Bottom Rev.
PAGE 32
ADP2370/ADP2371 Data Sheet PACKAGING AND ORDERING INFORMATION OUTLINE DIMENSIONS 2.48 2.38 2.23 3.00 BSC SQ 8 5 EXPOSED PAD INDEX AREA 1 BOTTOM VIEW TOP VIEW 0.80 MAX 0.55 NOM 0.80 0.75 0.70 SEATING PLANE 4 0.30 0.25 0.18 1.74 1.64 1.49 0.50 BSC 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF PIN 1 INDICATOR (R 0.2) FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET.