Document
AAT1156
1MHz 700mA Step-Down DC-DC Converter General Description
The AAT1156 SwitchReg™ is a member of AnalogicTech™'s Total Power Management IC™ (TPMIC™) product family. The step-down switching converter is ideal for applications where high efficiency is required over the full range of load conditions. The 2.7V to 5.5V input voltage range makes the AAT1156 ideal for single-cell lithium-ion/polymer battery applications. Capable of more than 700mA with internal MOSFETs, the current-mode controlled IC provides high efficiency over a wide operating range. Fully integrated compensation simplifies system design and lowers external parts count. The AAT1156 is available in the 16-pin 3x3mm QFN package and is rated over the -40°C to +85°C temperature range.
Features
• • • • • • • • • • • • • • •
SwitchReg™
VIN Range: 2.7 to 5.5 Volts Up to 95% Efficiency 110mΩ RDS(ON) Internal Switches <1µA Shutdown Current 1MHz Step-Down Switching Frequency Fixed or Adjustable VOUT ≥ 0.8V Integrated Power Switches Current Mode Operation Internal Compensation Stable with Ceramic Capacitors Internal Soft Start Over-Temperature Protection Current Limit Protection 16-Pin QFN 3x3mm Package -40°C to +85°C Temperature Range
Applications
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• • • • • •
Cellular Phones Digital Cameras MP3 Players Notebook Computers PDAs Wireless Notebook Adapters
Typical Application
U1 AAT1156 12 R1 100 C1 10µF 11 10 7 9 6 C2 0.1 µF 8 5 VP VP VP EN VCC LL NC SGND FB LX LX LX NC PGND PGND PGND 4 15 14 13 16 3 2 1 R4 59k C3, C4 2 x 22µF L1 4.7µH R3 187k
INPUT
2.5V
(VOUT = 2.5V; L = 4.7µH; CDRH3D16)
100 95
AAT1156 Efficiency
VIN = 3.0V VIN = 4.2V VIN = 3.6V
Efficiency (%)
90 85 80 75 70 65 60 55 50 1 10 100 1000
C1 Murata 10µF 6.3V X5R GRM42-6X5R106K6.3 C3-C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805 L1 Sumida CDRH3D16-4R7NC
Output Current (mA)
1156.2005.11.1.2
1
AAT1156
1MHz 700mA Step-Down DC-DC Converter Pin Descriptions
Pin #
1, 2, 3 4
Symbol
PGND FB
Function
Main power ground return pin. Connect to the output and input capacitor return. (See board layout rules.) Feedback input pin. This pin is connected to the converter output. It is used to set the output of the converter to regulate to the desired value via an internal resistive divider. For an adjustable output, an external resistive divider is connected to this pin on the 1V model. Signal ground. Connect the return of all small signal components to this pin. (See board layout rules.) Mode selector switch. When pulled low, the device enters light load mode. Enable input pin. A logic high enables the converter; a logic low forces the AAT1156 into shutdown mode, reducing the supply current to less than 1µA. The pin should not be left floating. Not internally connected. Bias supply. Supplies power for the internal circuitry. Connect to input power via low pass filter with decoupling to SGND. Input supply voltage for the converter power stage. Must be closely decoupled to PGND. Connect inductor to these pins. Switching node internally connected to the drain of both high- and low-side MOSFETs. Exposed paddle (bottom); connect to PGND directly beneath package.
5 6 7
SGND LL EN
8, 16 9 10, 11, 12 13, 14, 15 EP
NC VCC VP LX
Pin Configuration
QFN33-16 (Top View) LX LX LX NC
16 15 14 13
PGND PGND PGND FB
1 2 3 4 5 6 7 8
12 11 10 9
VP VP VP VCC
NC EN LL SGND
2
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Absolute Maximum Ratings1
Symbol
VCC, V VLX VFB VEN TJ VESD
Description
VCC, VP to GND LX to GND FB to GND EN to GND Operating Junction Temperature Range ESD Rating2 - HBM
Value
6 -0.3 to VP+0.3 -0.3 to VCC+0.3 -0.3 to 6 -40 to 150 3000
Units
V V V V °C V
Thermal Characteristics
Symbol
ΘJA PD
Description
Maximum Thermal Resistance (QFN33-16) Maximum Power Dissipation (QFN33-16)4 (TA = 25°C)
3
Value
50 2.0
Units
°C/W W
Recommended Operating Conditions
Symbol
T
Description
Ambient Temperature Range
Value
-40 to 85
Units
°C
1. Stresses above those listed in Absolute Maximum Ratings may cause damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Human body model is 100pF capacitor discharged through a 1.5kΩ resistor into each pin. 3. Mounted on a demo board (FR4, in still air). 4. Derate 20mW/°C above 25°C. 1156.2005.11.1.2
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AAT1156
1MHz 700mA Step-Down DC-DC Converter Electrical Characteristics
VIN = VCC = VP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Symbol
VIN VOUT VIL VIH VUVLO VUVLO(HYS) IIL IIH IQ ISHDN ILIM
Description
Input Voltage Range Output Voltage Tolerance Input Low Voltage Input High Voltage Under-Voltage Lockout Under-Voltage Lockout Hysteresis Input Low Current Input High Current Quiescent Supply Current
Conditions
VIN = VOUT + 0.2 to 5.5V, IOUT = 0 to 700mA
Min
2.7 -3
Typ
Max
5.5 3 0.6
Units
V % V V V mV µA µA µA µA A mΩ mΩ % %/V kHz .