PM8800 STMicroelectronics, PM8800 Datasheet - Page 5

• Manufacturer Part Number: PM8800
• Description: Integrated IEEE 802.3af compliant PoE-PD interface and PWM controller with support of external source
• Manufacturer: STMicroelectronics

PM8800A
1.2
Block diagram
Figure 3.
Figure 4.
COMP
AGND
FB
SS
discharge
charge
10µA
10µA
10 A
AUXI_IRL
10 A
Block diagram of the PoE PD interface
Block diagram of the current mode PWM controller
RCLASS
1.25V
3.3V
DCCL
VSS
VIN
+
-
discharge
E/A
fast
3.3V
3.3V
+
-
LOGIC
EN
SS
3.3V
+
-
+
-
+
-
24.5k
2.5kOhm
1.4V
1.4V
1.4V
2V
+
-
discharge
charge
CS
RT
Interface
Manager
R
Classification
Detection
threshold
threshold
Current and
R
Controller
Compensation
Voltage
Sense
Gate
Oscillator
Slope
Typical application circuit and block diagram
0.5V
0.7V
+
+
-
-
Zener Ref
1.25V
+
-
+
+
OC1
-
OC2
-
PWM
Protection
Thermal
45 A
45µA
1.4V
0.6V
AUXII
Manager
+
-
AUX
threshold
PWM
logic
UVLO
Cycle by cycle over current
80% duty cycle limit
(PM8800A)
Leading Edge Blanking
Hiccup on OC2 or
persistent OC1
protection
Good Ctrl
Power
Logic
DC/DC Enable
High Voltage
1.5V
controller
Regulator
S
R
DC/DC
Startup
SET
CLR
UVLO VCC
Q
Q
threshold
+
-
DC/DC
Enable
Driver
VCC
+
-
-
+
1.5V
VCC
2V
30uA
VCC
nPGD
GND
GD
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