RT8059

Part: RT8059GJ5 — Richtek Technology Corporation

Type: Synchronous Step-Down (Buck) DC/DC Converter

Description: 2.8–5.5 V input, 1 A synchronous PWM buck converter with 1.5 MHz fixed switching frequency, adjustable output from 0.6 V, and up to 95% efficiency in a TSOT-23-5 package.

Operating Conditions:

• Supply voltage: 2.8–5.5 V
• Operating temperature: -40 to 85 °C ambient (junction -40 to 125 °C)
• Adjustable output voltage: 0.6 V to VIN
• Fixed switching frequency: 1.5 MHz

Absolute Maximum Ratings:

• Max supply voltage (VIN to GND): 6.5 V
• Max junction temperature: 150 °C
• Storage temperature: -65 to 150 °C
• Lead temperature (soldering, 10 s): 260 °C
• ESD: 2 kV HBM, 200 V MM

Key Specs:

• Reference voltage: 0.6 V typ (0.588–0.612 V)
• Output voltage accuracy: ±3% (VIN = VOUT + ΔV to 5.5 V, 0 A < IOUT < 1 A)
• Quiescent current: 78 μA typ (IOUT = 0 mA, VIN = 3.6 V)
• Shutdown current: 0.1 μA typ, 1 μA max (EN = GND)
• P-MOSFET RDS(ON): 0.28 Ω typ (IOUT = 200 mA)
• N-MOSFET RDS(ON): 0.25 Ω typ (IOUT = 200 mA)
• P-channel current limit: 1.5 A typ
• Oscillator frequency: 1.5 MHz typ (1.2–1.8 MHz)
• UVLO threshold: 2.3 V typ, 0.2 V hysteresis
• Thermal shutdown: 150 °C typ
• Maximum duty cycle: 100%

Features:

• Wide input voltage range of 2.8–5.5 V
• Adjustable output from 0.6 V to VIN
• 1 A output current
• Up to 95% efficiency
• Internal synchronous rectifier, no Schottky diode required
• Automatic discontinuous PWM mode at light load
• Low dropout mode at 100% duty cycle
• Soft-start, over-temperature protection, and over-current protection
• RoHS compliant and halogen free

Applications:

• NIC cards
• Cellular telephones
• Personal information appliances
• Wireless and DSL modems
• MP3 players
• Portable instruments

Package:

• TSOT-23-5 (J5), green (halogen-free and Pb-free)

• Wide Input Voltage from 2.8V to 5.5V
• Adjustable Output from 0.6V to VIN
• 1A Output Current
• 95% Efficiency
• No Schottky Diode Required
• 1.5MHz Fixed Frequency PWM Operation
• Small TSOT-23-5 Package
• RoHS Compliant and Halogen Free

• NIC Card
• Cellular Telephones
• Personal Information Appliances
• Wireless and DSL Modems
• MP3 Players
• Portable Instruments

For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula :

$$P_{D(MAX)} = (T_{J(MAX)} - T_A) / \theta_{JA}$$

where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θ JA is the junction to ambient thermal resistance.

For recommended operating condition specifications of the RT8059, the maximum junction temperature is 125 ° C and TA is the ambient temperature. The junction to ambient thermal resistance, θ JA, is layout dependent. For TSOT23-5 packages, the thermal resistance, θ JA, is 255 ° C/W on a standard JEDEC 51-3 single-layer thermal test board. The maximum power dissipation at TA = 25 ° C can be calculated by the following formula :

PD(MAX) = (125 ° C -25 ° C) / (255 ° C/W) = 0.392W for TSOT-23-5 package

Table 1. Suggested Component Values

• V OUT (V) R1 (k ) R2 (k ) C FF (pF) L ( H) C OUT ( F) X5R 16V 0805
• 1 38.3 56.2 22 to 39 1.5 10
• 1.2 56 56 15 to 39 1.5 10
• 1.8 113 56.2 0 to 8.2 2.2 10
• 2.5 178 56 0 to 12 2.2 10
• 3.3 249 54.9 0 to 8.2 2.2 10

Note : All the input and output capacitors are the suggusted values, refering to the effective capacitances, subject to any de-rating effect, like a DC Bias.