LT8609_15 Datasheet, PDF (1/22 Pages) Linear Technology – 42V, 2A/3A Peak Synchronous Step-Down Regulator with 2.5A Quiescent Current

LT8609
42V, 2A/3A Peak
Synchronous Step-Down Regulator
with 2.5µA Quiescent Current
Features
nn _{Wide Input Voltage Range: 3.0V to 42V}
nn _{Ultralow Quiescent Current Burst Mode}^® _Operation:
nn _{<2.5µA IQ Regulating 12VIN to 3.3VOUT}
nn _{Output Ripple <10mVP-P}
nn _{High Efficiency 2MHz Synchronous Operation:}
nn _{>93% Efficiency at 1A, 5VOUT from 12VIN}
nn _{2A Maximum Continuous Output, 3A Peak Transient}
Output
nn _{Fast Minimum Switch-On Time: 45ns}
nn _{Adjustable and Synchronizable: 200kHz to 2.2MHz}
nn _{Spread Spectrum Frequency Modulation for Low EMI}
nn _{Allows Use of Small Inductors}
nn _{Low Dropout}
nn _{Peak Current Mode Operation}
nn _{Accurate 1V Enable Pin Threshold}
nn _{Internal Compensation}
nn _{Output Soft-Start and Tracking}
nn _{Small 10-Lead MSOP Package}
Applications
nn _{General Purpose Step Down}
nn _{Low EMI Step Down}
Description
The LT^®8609 is a compact, high efficiency, high speed
synchronous monolithic step-down switching regula-
tor that consumes only 1.7µA of quiescent current. The
LT8609 can deliver 2A of continuous current with peak
loads of 3A (<1sec) to support applications such as GSM
transceivers which require high transient loads. Top and
bottom power switches are included with all necessary
circuitry to minimize the need for external components.
Low ripple Burst Mode operation enables high efficiency
down to very low output currents while keeping the output
ripple below 10mV. A SYNC pin allows synchronization
to an external clock, or spread spectrum modulation of
switching frequencies for low EMI operation. Internal
compensation with peak current mode topology allows
the use of small inductors and results in fast transient
response and good loop stability. The EN/UV pin has an
accurate 1V threshold and can be used to program V_IN
undervoltage lockout or to shut down the LT8609 reducing
the input supply current to 1µA. A capacitor on the TR/SS
pin programs the output voltage ramp rate during start-up
while the PG flag signals when V_OUT is within ±8.5% of the
programmed output voltage as well as fault conditions.
The LT8609 is available in a small 10-lead MSOP package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Typical Application
V_IN
5.5V TO 40V
5V, 2MHz Step Down
V_IN
BST
4.7µF ON OFF EN/UV
SYNC
SW
LT8609
INTV_CC
TR/SS
PG
RT
FB
1µF 18.2k
GND
0.1µF _2.2µH
10pF
V_OUT
5V
2A
1M
187k
22µF
8609 TA01a
100
95
90
85
80
75
70
65
60
55
50
0
12V_IN to 5V_OUT Efficiency
f_SW = 2MHz
0.50 1.00 1.50 2.00 2.50
I_OUT (A)
8609 TA01b
For more information www.linear.com/LT8609
8609f
1