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ACT4528 Schematic ( PDF Datasheet ) - Active-Semi

Teilenummer ACT4528
Beschreibung 40V/3.0A CV/CC Buck Converter
Hersteller Active-Semi
Logo Active-Semi Logo 




Gesamt 13 Seiten
ACT4528 Datasheet, Funktion
ACT4528
Rev 1.2, December 28th, 2015
40V/3.0A CV/CC Buck Converter Featuring QC2.0 and USB Auto-Detect
FEATURES
40V Input Voltage Surge
4.5V-36V Operational Input Voltage
5.1V/9.1V/12.1V Output with +/-1% Accuracy
Up to 3.0A Output current
Constant Current Regulation Limit
QC2.0 Decoding + USB Auto-Detect
Support Apple 2.4A, Samsung and BC1.2
Devices
Hiccup Mode Protection at Output Short
>90% Efficiency at Full Load
0.5mA Low Standby Input Current
5.7V/10.1V/13.5V Output Over-voltage
Protection for 5.1V/9.1V/12.1V Outputs
Cord Voltage Compensation
Meet EN55022 Class B Radiated EMI Standard
8kV ESD HBM Protection on DP and DM
SOP-8EP Package
APPLICATIONS
Car Charger
Cigarette Lighter Adaptor (CLA)
Rechargeable Portable Device
CV/CC regulation DC/DC converter
GENERAL DESCRIPTION
ACT4528 is a wide input voltage, high efficiency
step-down DC/DC converter that operates in either
CV (Constant Output Voltage) mode or CC
(Constant Output Current) mode. ACT4528 has
QC2.0 decoding built in to provide 5.1V/9.1V/12.1V
outputs as requested by attached portable devices.
It also supports Apple 2.4A, Samsung and BC1.2
devices to charge at full current rate.
ACT4528 has accurate output current limits under
constant current regulation to meet MFi
specification. It can provide up to 3.0A output
current at 125kHz switching frequency. ACT4528
utilizes adaptive drive technique to achieve good
EMI performance while main >90% efficiency at full
load for mini size CLA designs. ACT4528 also has
output short circuit protection with hiccup mode.
The average output current is reduced to below
6mA when output is shorted to ground. Other
features include output over voltage protection and
thermal shutdown.
ACT4528 is available in a SOP-8EP package and
require very few external components for operation.
Typical Application Circuit
4.5V to 40V
C1 C2
47μF 10μF
CSN HSB
C3
22nF
Rcs
25mΩ
IN SW
ACT4528
CSP
L1
47μH
GND DP DM
D1
C4 C5
C6
22μF 220μF 2.2μF
SK54L
5V/9V/12V
Vout
D-
D+
GND
V/I Profile
Innovative PowerTM
Vout
12.1V
9.1V
5.1V
3.2V
Iout
2.65A
-1-
www.active-semi.com
Copyright © 2015 Active-Semi, Inc.






ACT4528 Datasheet, Funktion
FUNCTIONAL BLOCK DIAGRAM
VIN
UVLO
PWM
Controller
HSB
USB
Auto
Detect
QC2.0
Detect
Driver
DP
OVP
Current Sense
and Control
DM
CSP
CSN
ACT4528
Rev1.2, December 28th, 2015
70m
SW
4.7
GND
FUNCTIONAL DESCRIPTION
Output Current Sensing and Regulation
Sense resistor is connected to CSP and CSN. The
sensed differential voltage is compared with interval
reference to regulate current. CC loop and CV loop
are in parallel. The current loop response is allowed
to have slower response compared to voltage loop.
However, during current transient response, the
inductor current overshoot/undershoot should be
controlled within +/-25% to avoid inductor
saturation.
Cycle-by-Cycle Current Control
The conventional cycle-by-cycle peak current mode
is implemented with high-side FET current sense.
Input Over Voltage Protection
The converter is disabled if the input voltage is
above 42V (+/-2V). Device resumes operation
automatically 40ms after OVP is cleared.
Output Over Voltage Protection
Device stops switching when output over-voltage is
sensed, and resumes operation automatically when
output voltage drops to OVP- hysteresis.
Output Over Voltage Discharge
Discharge circuit starts to discharge output through
CSP pins when output over voltage is detected.
Discharge circuit brings 12V down to 5V in less
than 100ms.
Output Under-Voltage Protection /
Hiccup Mode
There is a under voltage protection (UVP)
threshold. If the UVP threshold is hit for 10us, an
over current or short circuit is assumed, and the
converter goes into hiccup mode by disabling the
converter and restarts after hiccup waiting period.
Cord Compensation
In some applications, the output voltage is
increased with output current to compensate the
potential voltage drop across output cable. The
compensation is based on the high side feedback
resistance.
The compensation voltage is derived as:
ΔVout = (VCSP-VCSN)*K
This voltage difference could be added on the
reference or turning the (VCSP-VCSN) voltage into a
sink current at FB pin to pull Vout higher than
programmed voltage.
The cord compensation loop should be very slow to
avoid potential disturbance to the voltage loop. The
voltage loop should be sufficiently stable on various
cord compensation setting.
Thermal Shutdown
If the TJ increases beyond 160°C, ACT4528 goes
into HZ mode and the timer is preserved until TJ
drops by 30°C.
Innovative PowerTM
- 6 - www.active-semi.com
Copyright © 2015 Active-Semi, Inc.

6 Page









ACT4528 pdf, datenblatt
ACT4528
Rev1.2, December 28th, 2015
TYPICAL PERFORMANCE CHARACTERISTICS
(Schematic as show in typical application circuit, Ta = 25°C, unless otherwise specified)
Voltage Transient (5V-9V)
Voltage Transient (9V-5V)
CH1
CH1
CH1: VOUT, 2V/div
TIME: 10ms//div
Voltage Transient (5V-12V)
CH1
CH1: VOUT, 2V/div
TIME: 10ms//div
CH1: VOUT, 2V/div
TIME: 10ms//div
Voltage Transient (12V-5V)
CH1
CH1: VOUT, 2V/div
TIME: 10ms//div
Innovative PowerTM
- 12 -
www.active-semi.com
Copyright © 2015 Active-Semi, Inc.

12 Page





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