HR1000A – RESONANT HALF-BRIDGE CONTROLLER
Latch Operation
from 0V to 2V. However, there is no simple
relationship between tOC and CTimer. Select CTimer
based on experimental results (based on
experiments: CTimer may increase operating time
by 100ms).
After the voltage on CTimer rises to 2V, the
130uA current source continues to charge it
until the voltage reaches the shutdown
threshold (3.5V). This period is approximately:
tOP = 104 ⋅ tTimer
tOC
tOP
tSTOP
tSS
Figure 13: Latch Function Block
VCC
SS
The HR1000A provides a simple latch-off
function through the Latch pin. Applying an
t
2V
external voltage >1.85V causes the IC to enter
a latched shutdown. After IC is latched, its
consumption drops, as shown by the residual
current in the EC table. Resetting the IC
requires dropping the VCC voltage below the
UVLO threshold.
t
t
t
t
t
t
ICr
CS
0.8V
3.5V
2V
TIMER
Vout
0.3V
Input Voltage Sensing
The HR1000A can stop when the input voltage
drops below a specified value, and then
restarted when the input voltage goes back to
normal. This function guarantees that the
resonant half-bridge converter always operates
within the specified input voltage range. The IC
senses voltage on BO through the tap of a
resistor divider connected to the rectified AC
voltage or the PFC output.
PFC
Over load /
Short circuit
Normal
operation
Shutdown
Soft-start
Pmin
Figure 12: Delayed Shutdown and Soft-start Time
Sequence
During this period, the switching frequency
remains at fstart to limit the energy transferred.
When the shutdown threshold triggers, the gate
drive turns off and the 130µA current source
shuts down. Then RTimer slowly discharges CTimer
This procedure lasts until the CTimer voltage
drops below 0.3V, then the IC restarts. This
time period is:
Figure 14 shows the line-sensing internal block
diagram.
.
HV Input bus
Shutdown
3.5
tOFF =RTimer ⋅CTimer ⋅ln
≈ 2.5RTimer ⋅CTimer
5.5V
RH
0.3
BO
7
VinOK
Figure 12 shows the operation’s time sequence.
12μA
1.25V
RL
HR1000A
Figure 14: Input Voltage Sensing Block
HR1000A Rev. 1.01
8/30/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
18
MPS [ MONOLITHIC POWER SYSTEMS ]
