ACE732E Datasheet, PDF (6/10 Pages) ACE Technology Co., LTD. – 6V/3.5A, Fast Response, Step-Down Converter

ACE732E
6V/3.5A, Fast Response, Step-Down Converter
Transient Response: VIN=5V, VOUT=1.2V, IOUT=0.3-3A
Output Short Response: VIN=5V, VOUT=1.2V, Output short to GND
FUNCTIONAL DECRIPTIONS
ACE732E belongs to a new breed of high frequency synchronous Step-Down converter that combines the
advantages of voltage mode control and Constant On time control. Its adaptive Constant-On-Time control
dynamically changes switch on time to achieve a constant switching frequency. It does not have the
minimum on-time constrain normally a fixed-frequency current mode Step-down requires, allowing it to go
down to very low duty ratios without affecting loop stability. The voltage mode nature of ACE732E also
provides a more superior load transient response as well as a seamless transition from PFM to PWM modes.
It can also operate up to 100% duty. It has a cycle by cycle current limit and a hiccup mode that protects
against dead-short condition. It includes soft-start, UVLO and thermal shutdown protection.
Adaptive Constant On-Time Control
ACE732E uses an adaptive Constant-On-Time control scheme that the ON time is dynamically adjusted
according to VIN and VOUT so to achieve a nearly constant switching frequency. This control scheme
provides simpler compensation and superior transient response over traditional constant frequency current
mode control, while still maintaining the advantage of switching at a constant frequency at about 1.5MHz. It
also provides a seamless transition from PFM to PWM that normally a constant frequency current mode
control scheme is hard to achieve. Further mode, because it is a COT control scheme, the system can
achieve high step-down ratio at ease, because lower constrain on the minimum on- time requirement
existing in constant frequency scheme.
100% Duty operation
ACE732E can operate at 100% duty cycle under dropout condition for high efficiency purpose.
Current Limit and Short-Circuit protection
ACE732E employs a cycle-by-cycle peak current limit and it also has a hiccup mode that protects the circuit
during dead-short condition. When the dead-short condition is removed, the IC goes back to normal
operation.
Soft-start
ACE732E has an internal soft-start circuitry to reduce supply inrush current during startup conditions.
When the device exits under-voltage lockout (UVLO), shutdown mode, or restarts following a
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