PM8834 STMicroelectronics, PM8834 Datasheet - Page 11

• Manufacturer Part Number: PM8834
• Description: IC MOSFET DVR 4A DUAL SOIC-8
• Manufacturer: STMicroelectronics
• Type: Low Side Mosfet Driverr

Specifications of PM8834

• Configuration: Low-Side
• Input Type: PWM
• Delay Time: 35ns
• Current - Peak: 4A
• Number Of Configurations: 2
• Number Of Outputs: 2
• Voltage - Supply: 5 V ~ 18 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Product: Driver ICs - Various
• Rise Time: 10 ns
• Fall Time: 10 ns
• Propagation Delay Time: 45 ns
• Supply Voltage (max): 18 V
• Supply Voltage (min): 4.5 V
• Supply Current: 3.5 mA
• Maximum Power Dissipation: 1.4 W
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Number Of Drivers: 2
• Output Current: 500 mA
• Output Voltage: 10 V
• Wide Input Supply Voltage Range: 5 V to 18 V
• Wide Operative Temperature Range: -40 °C to 105 °C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• High Side Voltage - Max (bootstrap): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PM8834
5.2
Power dissipation
PM8834 embeds two high current low side drivers that can be used to drive high capacitive
MOSFETs. This section estimates the power dissipated inside the device in normal
applications.
Two main terms contribute in the device power dissipation: bias power and drivers' power.
●
●
When designing an application based on PM8834 it is recommended to take into
consideration the effect of external gate resistors on the power dissipated by the driver.
External gate resistors helps the device to dissipate the switching power since the same
power P
resulting in a general cooling of the device.
Referring to
with two different mosfets: P-DMOS to drive the external gate high and N-DMOS to drive the
external gate low (with their own R
represented in this case as a capacitance (C
the external power MOSFET to reach the driving voltage (V
and discharged at the driver switching frequency F
The total power Psw is dissipated among the resistive components distributed along the
driving path. According to the external gate resistance and the power-MOSFET intrinsic
gate resistance, the driver dissipates only a portion of Psw as follow (per section):
The total power dissipated from the driver can then be determined as follow:
P
P
SW
=
P
Bias power (P
pins and it is simply obtained as follow:
Drivers' power is the power needed by the driver to continuously switch ON and OFF
the external MOSFETs; it is a function of the switching frequency and total gate charge
of the selected MOSFETs. It can be quantified considering that the total power P
dissipated to switch the MOSFETs is dissipated by three main factors: external gate
resistance (when present), intrinsic MOSFET resistance and intrinsic driver resistance.
This last term has to be determined to calculate the device power dissipation.
The total power dissipated by each section to switch an external mosfets with gate
charge Q
P
P
=
DC
DC
SW
1
-- - C
2
SW
+
⋅
=
=
2 P
will be shared between the internal driver impedance and the external resistor
G
V
Figure
F
⋅
CC
⋅
SW
G
(
SW
V
is:
⋅
⋅
CC
I
(
CC
Q
DC
6, classical mosfet driver can be represented by a push-pull output stage
)
2
G
) depends on the static consumption of the device through the supply
⋅
⋅
Fsw
V
CC
)
⋅
⎛
⎝
----------------------------------------- -
R
Doc ID 15086 Rev 2
hi
+
R
dsON
R
Gate
hi
: R
+
R
hi,
i
+
G
R
) that stores the gate-charge (Q
----------------------------------------- -
R
lo
lo
). The external power mosfet can be
+
SW
R
R
Gate
lo
.
+
R
CC
i
⎞
⎠
). This capacitance is charged
Design guidelines
G
) required by
SW
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