ACT4529
Rev 4, 06-Jan-2017
FUNCTIONAL BLOCK DIAGRAM
HSB
VIN
UVLO
PWM
Controller
PDC
70mΩ
USB
Auto
Detect
QC2.0
Detect
SW
Driver
4.7Ω
DP
Current Sense
and Control
OVP
DM
CSP
CSN
GND
FUNCTIONAL DESCRIPTION
Output Under-Voltage Protection /
Hiccup Mode
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.
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.
Input Brownout Protection
(ACT4529YH-T1011 only)
Cycle-by-Cycle Current Control
If the input voltage drops below 8V but higher than
UVLO for 450ms while in QC or PDC mode, the
output voltage turns off and QC or PDC mode is
disabled. If the output voltage drops below 3.7V, the
timer restarts and waits for 450ms before
attempting to restart the output voltage. When
output voltage rises above 3.9V and detects the
input voltage below 8V, timer restarts. If the input
voltage is below 8V after 450ms, the output turns
off. The cycle continues until the input voltage
increases above 8.2V,for longer than 450ms, then
output turns on, the IC renegotiates the PD and QC
protocols, and normal operation restarts.
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.
Thermal Shutdown
Output Over Voltage Discharge
If the TJ increases beyond 160°C, ACT4529 goes
into HZ mode and the timer is preserved until TJ
drops by 30°C.
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.
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- 6 -
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