PM6685 STMicroelectronics, PM6685 Datasheet - Page 24

• Manufacturer Part Number: PM6685
• Description: IC CTLR DUAL SYNC STDN 5X5VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6685

• Applications: Controller, Notebook Power System
• Voltage - Input: 6 ~ 28 V
• Number Of Outputs: 2
• Voltage - Output: -3.3V, 5V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5 V, 3.3 V
• Output Current: 0.1 A
• Input Voltage: 5.5 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 10 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device description
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Figure 33. R
An internal 100 μA ΔI
a voltage drop on R
voltage drop, the controller doesn’t initiate a new cycle. A new cycle starts only when the
sensed current goes below the current limit.
Since the current limit circuit is a valley current limit, the actual peak current limit is greater
than the current limit threshold by an amount equal to the inductor ripple current. Moreover
the maximum output current is equal to the valley current limit plus half of the inductor ripple
current:
Equation 5
The output current limit depends on the current ripple, as shown in
Figure 34. Current waveforms in current limit conditions
Being fixed the valley threshold, the greater the current ripple is, greater the DC output
current is
DSON
sensing technique
CSENSE
L
current source (I
. If the voltage across the sensing element is greater than this
Doc ID 11674 Rev 8
I
LOAD
(max)
CSENSE
=
) is connected to C
I
Lvalley
+
Δ
2
I
L
SENSE
Figure 34 on page
pin and determines
PM6685
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