PCA8538UG(2014) 查看數據表（PDF） - NXP Semiconductors.
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PCA8538UG Datasheet PDF : 107 Pages
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NXP Semiconductors
PCA8538
Automotive 102 x 9 Chip-On-Glass LCD segment driver
Table 32. Output resistance of the charge pump
RITO(VSS2), RITO(VDD2), RITO(VLCDOUT) = 50 .
Charge pump configuration Ro(VLCDOUT) (typical)
VLCD = 2 VDD2
2.5
VLCD = 3 VDD2
6
VLCD = 4 VDD2
10.5
VLCD = 5 VDD2
18
Unit
k
k
k
k
Remark: The PCA8538 has a built-in automatic limitation of VLCD, set to 12 V. The
maximum VLCD that can be programmed is expressed by the following equation:
VLCDmax = min12 V, n VDD2 – RoVLCDOUT Iload , where n is the multiplication factor of
the charge pump. Iload is the overall current sink by the segments and backplanes outputs
depending on the display, plus the on-chip VLCD current consumption.
With these values, it can be calculated how much current the charge pump can drive
under certain conditions, as shown in Figure 17 and Figure 18.
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Conditions: VDD2 = 3.0 V, RITO(VSS2), RITO(VDD2), RITO(VLCDOUT) = 50 , Tamb = 27 C.
Charge pump configuration:
(1) VLCD = 2 VDD2.
(2) VLCD = 3 VDD2.
(3) VLCD = 4 VDD2.
(4) VLCD = 5 VDD2.
Iload is the overall current sink by the segments and backplanes outputs depending on the display,
plus the on-chip VLCD current consumption.
Reading example: VLCD can be programmed to 10 V by using the charge pump configuration (3)
or (4). With configuration (3), VLCD can be programmed to 10 V for a current load up to about
120 A. With configuration (4), VLCD can be programmed to 10 V for a current load up to about
260 A.
Remark: Only the charge pump configuration (4) allows programming VLCD = 12 V when
VDD2 = 3.0 V.
Fig 17. Charge pump driving capability with VDD2 = 3.0 V
PCA8538
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 4 — 26 September 2014
© NXP Semiconductors N.V. 2014. All rights reserved.
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