BD9123MUV_14 Datasheet, PDF (13/28 Pages) Rohm – Synchronous Buck Converter with Integrated FET

BD9123MUV
Datasheet
(1) Short-Current protection circuit with time delay function
It turns OFF the output to protect the IC from breakdown when the incorporated current limiter is activated continuously
for the fixed time (tLATCH) or more. The output may be recovered from OFF state by restarting EN or by re-unlocking
UVLO.
VCC
Output Short circuit
Threshold Voltage
VOUT
IL Limit
IL
Output voltage OFF Latch
Output voltage
OFF
t1<tLATCH
Operated mode
t2=tLATCH
Output voltage
OFF
Operated mode
UVLO
Timer Latch
UVLO
Figure 29. Short-current protection circuit with time delay timing chart
4. Information on Advantages
Advantage 1: Offers fast transient response with current mode control system.
Conventional product (Load response IO=0.1A to 0.6A)
BD9123MUV (Load response IO=0.6A to 0.1A)
VOUT
27mV
VOUT
IOUT
37mV
IOUT
Figure 30. Comparison of Transient Response
Advantage 2: Offers High Efficiency for all Load Range.
(a) For lighter load:
Utilizes the current mode control called SLLM^TM for lighter load, which reduces various dissipations such as switching
dissipation (PSW), gate charge/discharge dissipation (PGATE), ESR dissipation of output capacitor (PESR) and
ON-Resistance dissipation (PRON) that may otherwise cause degradation in efficiency for lighter load.
Achieves Efficiency Improvement for Lighter Load.
(b) For heavier load:
Utilizes the synchronous rectifying mode and the low ON-Resistance MOS FETs incorporated as power transistor.
ON-Resistance of Pch side MOS FET : 0.35mΩ(Typ)
ON-Resistance of Nch side MOS FET : 0.25mΩ(Typ)
Achieves Efficiency Improvement for Heavier Load.
Offers high efficiency for all load range with the improvements mentioned above.
100
SLLM
②
50 ①
PWM
①improvement by SLLM system
②improvement by synchronous rectifier
0
0.001 0.01
0.1
1
Output current IOUT[A]
Figure 31. Efficiency
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02.Oct.2014 Rev.002